Category Archives: Longevity

Metformin: Longevity research and genetics

A decades-old diabetes drug now holds promise for increasing healthspan. Research shows that metformin may reduce the risk of some of the diseases of aging, thus increasing the number of years someone is healthy.

What is metformin?

Metformin, also known as Glucophage, is the most commonly prescribed medication for reducing blood glucose levels. Metformin prescriptions target people with diabetes, prediabetes, and sometimes PCOS (polycystic ovarian syndrome).

Beyond diabetes, there are also many studies pointing to other positive benefits for metformin as a longevity or healthy aging medication.

How does metformin work?

Metformin has a couple of mechanisms of action:

  1. It decreases glucose production in the liver, which is especially important for overnight blood glucose regulations.
  2. It increases the uptake of glucose in muscles and other parts of the body.

Let’s take a close look at all three of these actions of metformin:

Decreases glucose production in the liver:
When glucose levels in the body fall, such as when fasting or even overnight when sleeping, the liver can produce glucose through a process called gluconeogenesis. This keeps glucose levels in the right range all day and night for people without diabetes.

The research on exactly how metformin decreases gluconeogenesis (glucose production) in the liver isn’t fully elucidated. There seem to be several possibilities:

  • First, metformin may act partially in the mitochondria, inhibiting complex I in the electron transfer chain. This would alter the ratio of AMP (adenosine monophosphate) to ATP (adenosine triphosphate), which triggers AMPK.  AMPK does a bunch of things, including decreasing gluconeogenesis.[ref]
  • Second, metformin may be altering the way mitochondria use lactate for energy. A January 2020 paper contends that metformin works through decreasing glucose 6-phosphate (G6P).[ref][ref]

New research also questions whether metformin reduces glucose production in the liver for people without type 2 diabetes. The studies indicate that glucose production in the liver may not decrease – and may possibly increase a bit to counteract the drop in blood glucose levels.[ref][ref]

Increases glucose uptake:
Blood glucose levels remain tightly regulated, and the release of insulin by the pancreas facilitates the uptake of glucose into cells. For most cells, glucose can’t cross the cell membrane without a transporter. The glucose transporters are known as GLUT1 through GLUT4, with different transporters in different cell types. The GLUT4 transporters are found in muscle tissue and fat cells. When blood glucose levels are high, the GLUT4 transporters are located in the cytosol of the cell (inside the cell), but when glucose levels fall, insulin levels rise. Insulin then binds to a receptor on the cell membrane, causing a cascade of actions that results in the GLUT4 transporters moving to the cell membrane. There, they can move glucose into the cells.

Metformin is thought to work in a way that keeps the GLUT4 transporters available on the cell surface so that the skeletal muscle cells can take up more glucose without needing more insulin.[ref]

Altered microbiome composition:
Research also shows that metformin alters the composition of the gut microbiome, promoting Akkermansia muciniphilia, a bacteria associated with a lower risk of obesity and a lower risk of inflammatory conditions in the intestines. The altered gut microbiome composition may also be a mechanism through which metformin helps with diabetes. Additionally, metformin has shown to increase short-chain fatty acid metabolism in the intestines.[ref][ref][ref]

PCOS and metformin:

Polycystic ovarian syndrome (PCOS) is characterized by insulin resistance and altered androgen hormone production. Studies show that metformin may be beneficial for women with PCOS. One study found that 12 weeks of metformin decreased testosterone levels and improved glucose effectiveness.[ref]

Metformin for Longevity and Aging:

Many researchers are now looking at aging as a disease. In fact, the World Health Organization recently added it to its classification system as a disease. With this idea in mind, let’s take a look at the use of metformin to prevent chronic diseases in aging.

Animal studies have repeatedly shown that metformin can increase lifespan. Most of the studies show that starting metformin in middle age or earlier can increase lifespan and healthspan.[ref][ref][ref]

But humans aren’t the same as mice, and the results of animal studies sometimes don’t hold true for people.

Human studies on metformin show:
A large meta-analysis found that people with diabetes and also taking metformin had lower all-cause mortality than non-diabetics. They also had lower cardiovascular disease and cancer rates. That is pretty amazing. The study also showed that diabetics taking metformin had lower rates of cancer than diabetics using other types of diabetes medications.[ref]

Another meta-analysis using data from over 1 million patients found significant reductions in both all-cause mortality and cardiovascular events. (20% for all-cause mortality and over 30% for cardiovascular events).[ref]

Other studies show a reduction in all-cause mortality and cancer-related mortality in people who take metformin.[ref]

Not all human studies show fantastic results:
In a study of heart attack patients, 4 months of metformin did not have beneficial long-term effects.[ref] Other studies show a possible impact that negates the benefits of aerobic exercise.[ref]

How can metformin extend healthspan?

One mechanism (other than decreased blood glucose levels) for a positive effect on healthy aging is that metformin may activate SIRT1. The sirtuins are a family of enzymes that are important for regulating cellular homeostasis, and SIRT1 (sirtuin 1) is important in healthy aging. A link exists between the activation of SIRT1 and lower rates of cardiovascular and metabolic diseases.[ref][ref]

Another mechanism through which metformin has shown to act is in the way that mitochondria use fatty acids for energy. The ACAD10 gene codes for an enzyme needed in beta-oxidation and animal studies show that metformin acts through the inhibition of mTORC1 to upregulate ACAD10.[ref]

Impact on muscles:

A Dec 2019 randomized crossover trial shows that 4 days of metformin doesn’t impact skeletal muscle activity. Interestingly, the authors note that metformin caused the participants to feel like exercise took more exertion. Thus, it may cause people to want to exercise a little less.[ref]

In another study in older adults (age ~62), 3 months of metformin seemed to attenuate the benefits of aerobic exercise.[ref]

Potential negative side effects from metformin:

Most importantly, there is an increased risk of lactic acidosis in people taking metformin. This may be more of a risk for people with underlying kidney problems.[ref]

Some people have gastrointestinal side effects from metformin. People with SLC22A1 variants (below) are more likely to have gastrointestinal problems.[ref]

Metformin metabolism and excretion:

Metformin circulates unbound because its metabolism doesn’t occur in the liver. Instead, the kidneys clear it from the body facilitated by SLC22A2 kidney cells. (more on this below)[ref]

Genetic variants associated with metformin response:

Like almost every drug or supplement, individuals respond differently to metformin. Below you can find some of the genetic variants associated with the altered response to metformin.

Note: This article is also cross-posted on

If you have genetic data from 23andMe or AncestryDNA, check out the genetics section of this article on Genetic Lifehacks.   


If you are interested in metformin for longevity, talk with your doctor about whether getting a prescription for it is right for you.

Alternatively, there is an online website that sells 3-month prescriptions of metformin, after you interact with their telemedicine doctor. The website is called Read through the information and be sure to understand the terms of the website.

Longer-term use of metformin increases the risk of vitamin B12 deficiency.[ref] Consider supplementing with vitamin B12, especially if you don’t eat a lot of foods that contain B12.

Berberine is a natural supplement that is often touted as a natural alternative to metformin in terms of blood sugar control. Read more about berberine.


GHK Peptide: neurogenesis, skin, and more

GHK-Cu is a tiny little peptide that can be absorbed transdermally. It is often advertised as a way to reduce skin aging.

While there are some good studies on it as a ‘beauty’ product, that is just the tip of the GHK-Cu iceberg. Let’s dive into the science of what this little peptide can do in the body — and also throw in a dash of cold-hard reality that it’s not a miracle cure-all.

What is GHK-Cu?

GHK stands for Gly–His–Lys, which are the abbreviations for the amino acids that make up this peptide. A peptide consists of a short chain of amino acids and proteins are longer chains.

GHK naturally resides in your bloodstream in small amounts. It can easily bind to copper, and thus you will usually see the peptide as GHK-Cu, with the Cu being the chemical symbol for copper.

Researchers think GHK naturally liberates from extracellular matrix proteins, specifically a collagen chain, in response to soft tissue damage. GHK then promotes wound healing and regeneration of tissues.[ref]

ROS, lung injury from infections:

Acute lung injury, including ARDS, is characterized by inflammation and tissue injury in the small alveoli. This is what kills people with COVID, pneumonia, etc.

To create a tissue model of lung injury, researchers use lipopolysaccharides (LPS). Found on the outer membrane of gram-negative bacteria, lipopolysaccharides cause a big immune response in the body. When added to the lungs, LPS causes an inflammatory response injuring the lung tissue due to high levels of ROS (reactive oxygen species).

Researchers have shown that GHK-Cu suppressed TNF-alpha and IL-6 (inflammatory cytokines) from overexpression. This reduced tissue damage in the lungs when exposed to the lipopolysaccharide (LPS).[ref]

Why is this a big deal? If it works in humans, this could potentially be a way to reduce the lung damage during ARDS or pneumonia. Pneumonia is often caused by gram-negative (LPS) bacteria.

Additional cell culture studies show that GHK reduces ROS levels in cells.[ref] While another cell study showed that GHK could restore function in COPD lung tissue.[ref]

Keep in mind that this research has a long way to go to prove efficacy in people with lung problems, but the mechanism and science here are interesting.

GHK and Gene Expression:

A gene expression analysis computer model shows that GHK changes the gene expression of thousands of genes — upregulating some and downregulating others. Of note, GHK upregulates several DNA repair genes as well as downregulating IGF1.[ref]


The majority of research on GHK-Cu centers around its effects on skin regeneration and wound healing. Research shows that GHK-Cu promotes collagen formation in the skin, which reduces fine lines and improves elasticity.[ref]

In skin culture studies, GHK-Cu increases the survival of stem cells in the skin. Stem cells regenerate skin cells more quickly in younger skin than older skin, so increasing stem cell survival might promote youthfulness of the skin.[ref][ref]

Similar to the effect seen in lung injury models, GHK-Cu also decreases inflammatory cytokines (IL-6 and TNF-alpha) in skin cells.[ref]

Note that a lot of the clinical trials on GHK-Cu for skincare are several decades old and the publications are not readily available on the internet. While many current articles reference these publications, I haven’t been able to read the studies for myself.


A trial using a complex of 5-ALA (another peptide) and GHK found that the peptide complex increased the hair count significantly compared to placebo over a 6 month trial period.[ref]

In an animal model of hair loss, GHK-Cu in solution or in a liposomal form has shown to increase hair growth and increase VEGF expression, thus likely improving blood circulation to the hair follicle.[ref]



The GHK-Cu peptide can be purchased in various places online and often sold as an additive for skin creams. It is a blue-green color from the copper at higher concentrations. Plus, the peptide is small enough to readily transport into the skin.

My take on it: While it is likely not the fountain of youth, the research on GHK-Cu does show that it likely improves the look and feel of skin. The question is always whether your source for purchasing GHK-Cu is legitimate and whether the concentration is high enough to make a difference.

Vitamin D for preventing respiratory infections

Have you ever wondered why you are much more likely to have a cold in the winter than in the summer? It turns out that researchers have puzzled over the seasonality of respiratory viruses for decades. In 1926, one scientist proposed that the seasonality was due to the vitamin found in dairy products and produced by sunlight exposure on the skin.[ref] This idea that vitamin D levels influence the seasonality of respiratory viruses had been tossed around ever since, in different variations.

This article will cover the more recent research on vitamin D levels, supplementation, and respiratory infections.

Can Vitamin D reduce the risk of respiratory infections?

First, a little context.

By respiratory infection, researchers are generally referring to colds, flu, and what the CDC calls ‘influenza-like illness’ or ILI. These are the viruses that go around every winter causing coughing, sneezing, wheezing, and runny noses.

  • The virus families that cause the common cold include rhinovirus, respiratory syncytial virus (RSV), adenovirus, and coronavirus.
  • The flu is caused by many different strains of influenza A or influenza B.
  • The CDC reports each year on ILI- influenza-like illness. This is a catch-all for influenza virus, RSV, rhinovirus, adenovirus, parainfluenza virus, coronavirus, and metapneumovirus.[ref]

Why do we care about respiratory viruses? Excluding data from the current COVID-19 pandemic (which is measured differently than previously), about 20% of the US population will get a respiratory infection each year. Several hundred thousand will end up in the hospital, and of those who are hospitalized with a respiratory infection, over 10% will die.[ref]

Additionally, respiratory tract infections statistically have links to an increased likelihood of heart attacks. A study looking at English hospital admission for people with myocardial infarction found that up to 5% of MI admissions may be due to respiratory virus infection in the previous week or two. Influenza was the least likely to be linked to MI, while the common cold viruses were most likely.[ref]

Vitamin D: the sunshine hormone

Vitamin D is produced in the skin as a reaction between UVB radiation from sunlight and cholesterol in the epithelial cells.

Once synthesized (or ingested), the liver transforms it into 25-(OH)D (25-hydroxyvitamin D). This is what you usually see on lab tests.

25-(OH)D is the main form available in the body, and it has a half-life of two to three weeks, so it can hang around for a while.

The kidneys transform 25-(OH)D into the active form of 1,25-(OH)2D. Certain other cells, such as immune system cells, can also transform the storage form of D into the active form. The active vitamin D hormone is transported throughout the body by vitamin D binding protein.

What does vitamin D do in a cell?  The active form of vitamin D binds to a vitamin D receptor in the nucleus of certain cell types and then turns on genes for transcription. There are several different types of cells with vitamin D receptors. For example, in macrophages, active vitamin D increases the production of anti-microbial peptides. In T-cells, vitamin D causes a shift towards Th2.[ref] In muscle cells, the binding of vitamin D to the receptor increases calcium and phosphate transport and increases muscle cell proliferation.[ref]

Regulating the immune response:

When challenged by a pathogen, the body needs to respond with enough immune response to vanquish the invader — but not going overboard and killing healthy cells. Many times, death from a respiratory virus is due to ARDS (acute respiratory distress syndrome) which is, at least in part, the body’s over-activation of the immune system in the lungs.

Vitamin D is important in activating immune system cells in a way that keeps the immune response from going overboard. Specifically, it skews the T-cells to mature as a regulatory T-cell phenotype rather than an inflammatory Th1/Th17 phenotype.[ref]

Clinical trials on Vitamin D and respiratory tract infections:

Research clearly shows that low vitamin D levels are associated with an increased risk of respiratory infections in both young and old[ref][ref]. But does that mean that taking a vitamin D supplement will help to prevent illness?

This can be a harder question to answer than you would think. There are a ton of trials on vitamin D supplementation, but many of the trials are small and use low doses of vitamin D in the trial.

A 2019 meta-analysis combined the data from 25 randomized controlled trials to try to answer the question of whether any vitamin D supplementation would reduce respiratory infections. The results showed that overall a daily or weekly vitamin D supplement decreased the average risk of respiratory infections by about 20%. Large doses via a shot of vitamin D did not have a statistical effect. Unsurprisingly, the benefit of supplementation was much greater in people who were vitamin D deficient (< 25 nmol/l). For vitamin D deficient individuals, supplemental vitamin D reduced respiratory tract infections by 70%.[ref]

What about COVID-19 vitamin D trials?

At the very beginning of the COVID-19 pandemic researchers associated vitamin D levels with a 20-fold increased risk of severe COVID-19.[ref]

But many argued that the association didn’t prove causation, nor did it tell us whether vitamin D supplementation would be beneficial for prevention. Years of previous research on the mechanism of action of vitamin D on the immune system didn’t seem to be enough to ‘prove causation’. Of course, even without clinical trials showing a benefit, there isn’t much of a risk to boosting vitamin D levels via a daily or weekly supplement.

A year down the road, the clinical trial results are rolling in, showing a clear benefit to supplementing with vitamin D, especially for people with lower baseline levels.

  • A Dec. 2020 study showed a significant reduction in mortality for COVID-19 hospitalized patients given vitamin D in the hospital. The patients who had received a shot of vitamin D (280,000IU) were 87% less likely to die from COVID-19.[ref]
  • A small trial of vitamin D (1,000 IU), magnesium, and vitamin B12 in hospitalized COVID patients showed a >80% reduction in the need for oxygen or ICU admission.[ref]
  • In another small trial of COIVD hospitalized patients, 50 of the patients received a large dose of oral vitamin D on days 1, 3, and 7 of hospitalization. All patients (control and vitamin D arm) also received other medications such as hydroxychloroquine and azithromycin as part of the normal hospital protocol. There was a significant difference in the patients needing admittance to the ICU — 1 / 50 for the vitamin D participants vs. 50% of the control group who didn’t receive vitamin D.[ref]

Should you take vitamin D before a vaccine?

If vitamin D modulates the immune response, should you stop taking it before a vaccine? Let’s take a look at the research studies on the topic.

Several studies have looked at the response to vaccines stratified by vitamin D levels. Most studies show that there is no difference in the response to the flu vaccine based on vitamin D levels.  There is a difference in response to the rubella vaccine based on vitamin D receptor gene variants, suggesting that vitamin D does play a role in that vaccine. With the hepatitis B vaccine, though, there is a clear association between lack of response to the vaccine and low vitamin D levels. In children, vitamin A and D supplementation increase the response to the tuberculosis vaccine.[ref]

While no overall benefit shows for higher vitamin D levels for the flu vaccine, a benefit for certain strains of influenza might exist.[ref]

What does seem to matter for vaccine response is age, genetics, stress, BMI, season, and time of day of vaccination.[ref] For example, morning vaccinations are more likely to elicit a stronger immune response for certain flu vaccines than later in the afternoon (3-5 pm).[ref]


Longevity Lifehacks:

Vitamin D supplementation reduces viral respiratory illnesses:

Vitamin D deficiency clearly impacts the immune response to viral respiratory illnesses. This has been the theory for over a century and has repeatedly been shown for the past couple of decades in research studies.

With respiratory illnesses either directly or indirectly causing many deaths in people over 65 each year, it seems like a ‘no brainer’ to keep your vitamin D levels up in the normal range. Younger people also benefit from reduced respiratory infections, and even if a viral isn’t likely to kill you, reducing the number of times you are sick in a year is a benefit for everyone.

Sunlight on your skin is a great option for increasing your vitamin D levels. Of course, this is not such a great option in the fall and winter months when UVB rays are scarce and it is too cold to expose much skin.

Supplemental vitamin D is cheap and readily available. Check the label on your vitamin D supplement, though, since a lot comes with cheap soybean or cottonseed oil. A better option is made with coconut or olive oil.

Check your vitamin D levels:

Get your doctor to order a vitamin D test the next time you go. OR – order a test on your own. Ulta Lab Tests offers it for $39, and there are other places online to order it as well.



MOTS-c: mitochondrial peptide that mimics exercise

A recent study in the journal Nature explains the latest research on a fascinating peptide known as MOTS-c.

A little background first:

Small peptide molecules are made up of 2-50 amino acids. Amino acids also makeup protiens but in chains longer than 50.

Mitochondria are the organelles responsible for energy production in your cells. And mitochondrial health is vital for all aspects of health and wellness – especially in aging.

Your mitochondria contain their own DNA that is separate from your nuclear DNA. But mitochondrial DNA is tiny in comparison to your whole genome — only about 13 protein-coding genes compared to more than 20,000 in the nucleus.

Peptides from mitochondria:

In addition to the protein-coding genes in the mitochondrial DNA, researchers recently identified short open reading frames (sORFs) that produce bioactive peptides.

One of the mitochondrial peptides is MOTS-c, and researchers are now figuring out that it does a lot…from regulating nuclear gene expression to promoting healthy metabolism. MOTS-c activates AMPK (5′ AMP-activated protein kinase) in skeletal muscles and improves whole-body energy metabolism.

The Nature study used cell samples from healthy young males to determine what the normal effects of exercise were on MOTS-c production in muscle cells. The results showed the levels of MOTS-c increased substantially in the four hours after exercise.

Next, the researchers used animals to determine the effect of giving the animals additional MOTS-c.

  • In young animals, giving MOTS-c at a high enough dose effectively reduced weight gain on a fattening diet.
  • In middle-aged and old animals, a two-week treatment with MOTS-c increased physical activity capability by two-fold.
  • In old animals, MOTS-c treatment improved healthspan also.


It is exciting to see the significant effects in animals, and the mechanisms through which the improvement in healthspan occurs.  We are not mice, though, so human trials and specifically randomized-controlled trials are needed to determine if exogenous MOTS-c will be effective in extending healthspan in people.

Boosting NAD+: amyloid proteins and mitochondrial dysfunction in muscles

A recent study in Cell reported on experiments regarding mitochondrial function and amyloid protein accumulation in the muscles.[ref]

The researchers used animal models and human muscle tissue to determine that amyloid-like protein deposits occur in muscle during aging. Amyloid proteins are aggregates of proteins that fold into long fibers. Perhaps the most well-known is amyloid-beta, which is the amyloid version of the APP protein and commonly found in Alzheimer’s brains.

Additionally, the researchers confirmed previous research showing a decline in mitochondrial function. Together, the amyloid proteins and reduced mitochondrial function “may represent a major common hallmark of muscle aging and disease.”

NAD+ also declines in muscle tissue in aging. The researchers showed that blocking the NAD+ salvage pathway, which reduced NAD+ in the cells, robustly induced the muscle cells to produce amyloid protein aggregations.

The opposite also seems to be true – boosting NAD+ attenuated the formation of amyloid protein aggregates in aging cells.

In an animal model, boosting NAD+ in older cells may reduce the amyloid deposits. The researchers tested nicotinamide riboside (NR) and olaparib (AZD). Nicotinamide riboside is commonly available as a supplement, and olaparib is a PARP inhibitor used for cancer treatment. Both were successful at ameliorating amyloid deposits in the muscle cells.

Why is this a big deal?

Loss of muscle mass in aging can lead to devastating health effects such as falling and breaking a hip. Oddly enough, researchers don’t really know what all goes into the loss of muscle in aging. This research is important both in pointing out mechanisms as well as a possible solution.


Note: Please do not take this as an endorsement or as medical advice. Instead, the links are for your reference – do your due diligence before starting on a new supplement or diet. 

Tru Niagen (Nicotinamide Riboside) on Amazon

Thorne Research – ResveraCel Nicotinamide Riboside plus Resveratrol

Calculating Biological Age

Calculators for predicting biological age:

The idea of biological age is that it shows how your lifestyle and genetics interact to estimate your cellular age more accurately than what the calendar says (chronological age). These biological age calculators are based on algorithms created using large population data sets and mortality outcomes.

1) – You can input your basic blood test biomarkers along with age and weight. It will predict your biological age.  The information on how it is calculated is included in this research paper.

2) Calculator – There is a second way of predicting biological age based on blood test biomarkers. The calculator is available on Google Drive, and you need to download it as open it in Excel or Google Sheets to use it. It is based on this research paper.  Here is a slideshow explaining the algorithm with pretty charts. The calculator isn’t as pretty as the interface, but it is supposed to be more accurate. The Ptypic Age result in the bottom row of the spreadsheet is giving you your phenotypical age. This basically correlates your mortality risk to the ‘phenotypical age’ — so if your phenotypical age is 50, your statistical mortality risk would be that of a 50-year-old.

For me, the two calculators came up with different biological or phenotypical ages (34 and 38). I was using last year’s blood work, so I would have been 46 when I got it done.

3) DNA methylation tests: There are companies selling kits for testing your biological age via DNA methylation. This method should be the most accurate (and expensive!) if you are wanting a more in-depth look. The myDNAge kits are $299.

4) Frailty Index- This article includes (towards the bottom) an old-school way to calculate your age by adding up your score for the “Frailty Index”. The concept is based on this 2017 study on aging.

Hallmarks of Aging

A 2013 paper in the journal Cell defines the way we think of aging as a disease. In the paper, the authors break down the process of aging into what they called the ‘Hallmarks of Aging’. It is essentially a schematic of how to organize the processes that cause aging.

I’m going to explain the terminology and essentially outline the paper into concepts that make more sense to me. Hopefully, this will help everyone reading this to understand the framework here on Longevity Lifehacks.

Hallmarks of Aging

The hallmarks of aging include:

  • Genomic instability
  • Telomere attrition
  • Epigenetic alterations
  • Loss of proteostasis
  • Deregulated nutrient sensing
  • Mitochondrial dysfunction
  • Cellular senescence
  • Stem cell exhaustion
  • Altered intercellular communication

Ok – that list has a lot in it. Let me break it down and try to explain what I understand from it.

Genomic instability:

Quick background: Genes are segments of DNA that code for proteins. Proteins can act as enzymes, causing reactions to happen, or proteins can make up the structure of the cell.

Your cells are constantly replicating and diving. Each time a cell replicates, it makes a copy of the DNA. Errors often occur in this replication process. Cells have a way of correcting errors, but this isn’t a perfect process. As we age, more and more damage occurs to the DNA.

Sometimes entire chromosomes can be lost or parts of a chromosome translocated during cellular replication.

Damage to the nuclear DNA can also come from various sources – exposure to a toxicant, UV exposure in sunlight, radiation, etc.

Basically, bad things happen to DNA. It can break, lose pieces, or get mucked up.

Mutations are just changes in a gene. A “T” gets swapped for a “G”. A little piece of the gene gets left out. Part of a gene gets included twice (or more).

After a while, all of these hits just keep adding up. A little mutation in a liver cell… A piece missing from an important gene in breast tissue… At some point, the transcription of the gene into a vital enzyme no longer works. Worse yet, a mutation occurs in a gene that is vital for preventing cancer.

Telomere attrition:

Telomeres are the region at the end of each chromosome in the nuclear DNA.

When DNA replicates, it can’t quite replicate the very end of the chromosome. So the telomere is a repeated section of nucleotides (TTAGGG – repeated over a thousand times) at the end of the chromosome. This prevents the genes at the end of the chromosome from being left off during replication.

However, some of the telomere section gets left off each time DNA replication occurs. Eventually, when the cell has replicated a number of times, the telomere is short enough to trigger a sequence of events leading to either cellular senescence or cell death.

It isn’t quite as cut and dry as just hitting a limit on the number of times a cell can replicate. An enzyme called telomerase can repair telomeres. It can add the repeats back to the end of DNA, restoring the length of the telomere. Telomerase is active in stem cells – and in cancer cells, which allows them to grow and divide without limits.

In aging, shorter telomeres are a sign of older biological age, indicating that some genes are at the end of their replication lifespan.

Cellular senescence

When telomeres get too short, cells no longer can reproduce. They can go into a state of cellular senescence where they are in bad shape, but not being killed off and recycled.

Cellular senescence may not occur in all tissues — it does occur in skin, lung, and spleen but possibly not in the heart, skeletal muscle, and kidneys.

Cellular senescence is good in a way since it prevents unchecked cellular proliferation (cancer/tumors).

BUT…  senescent cells also secrete pro-inflammatory signals. Think of cells like houses on a block in a nice, older neighborhood. A senescent cell is like the old run-down old house, perhaps infested with vermin, has a cranky old guy sitting on the porch yelling at kids to get off the lawn, generally bringing down the neighborhood. On the one hand, that senescent old house with the cranky old man is still there — and didn’t sell out to become a Walmart (cancer, in this analogy). But the flip side is that the senescent cell gives off signals that bring down the health of the surrounding cells.

Basically, too many cells become senescent with aging and need to be cleared out.

Epigenetic alterations:

All cells in the body have the same DNA in the nucleus, but cells look and function differently in different organs. The way that a liver cell differs from a skin cell is through turning on the genes needed for liver cells and turning off the genes unique to the skin.

This turning off or turning on of genes is called epigenetics.

Epigenetics gets a bit complicated. It involves the way that DNA is wrapped up around histones such that only certain regions of the DNA are available to be translated into proteins.

Epigenetics also involves markers that attach to specific regions of a gene to stop it from being translated into a protein — or other markers that cause the gene to be ’turned on’ and translated.

Histone methylation, an important epigenetic mechanism, has been shown in several studies to be important in aging. NAD+ and the sirtuin genes come into play here. (Read more about boosting NAD+ with nicotinamide riboside.)

Epigenetic changes, such as decreasing enzyme function, are an important cause of aging. There are also ways to epigenetically turn back the clock in a cell so that it looks a lot more like a young cell than an old cell.

Loss of Proteostasis:

Proteostasis means protein homeostasis, which refers to how the proteins in a cell need to be correctly formed and correctly folded so that they function well.

Misfolded proteins don’t work correctly – and, in fact, misfolded proteins can be a real problem in a cell. Take prions for example. Or the protein aggregation in Alzheimer’s or Parkinson’s.

In addition to misfolding, proteins can aggregate, or clump together.

Alzheimer’s disease, with misfolded amyloid-beta proteins, would come under this heading of ‘loss of proteostasis’.

Cataracts are also caused by misfolded proteins which bind together, forming a crystallized structure that can’t be repaired by the body.ref

Deregulated Nutrient Sensing:

The body knows when nutrients (e.g. glucose) are low and after a period of time will down-regulate the production of a bunch of things.

Restricting calories increases lifespan in small animals. This hasn’t been shown in humans, though, and there are questions around whether calorie restriction or the decrease of certain amino acids causes the increase in lifespan in animal models.

IFG-1 (insulin-like growth factor 1 ) is another player in this section of deregulated nutrient sensing. IGF-1 is produced in response to growth hormone, and – like insulin – can signal to cells that glucose is available. It is involved in both FOXO3 and mTOR, which are important proteins for longevity. Genetic variants that decrease IGF-1 are associated with longevity.

One reason that lower IGF-1 and/or growth hormone levels may increase longevity is that there is less overall cell growth and thus less of a chance for DNA or cellular damage. There is a limit, though, to how much decrease to IGF-1 an organism can handle. Balance.

Another molecule of interest in this section would be mTOR – mechanistic target of rapamycin. mTOR regulates anabolic activity by sensing amino acid concentrations. Genetically low levels of mTORC1 increase lifespan in animals.

Mitochondrial dysfunction

Mitochondria are the powerhouse of the cell. (Just had to say it 🙂

Within the mitochondria, a bunch of reactions take place that moves electrons around, eventually resulting in the ATP molecules that the cells use for energy.

Cells can have hundreds or even thousands of mitochondria. Egg cells have upwards of a half-million mitochondria in them.

Mitochondrial dysfunction increases with aging and can cause some of the diseases associated with aging.

On the other hand, mitochondrial biogenesis – the creation of more mitochondria – decreases with aging.

Resveratrol and metformin are both slightly poisonous to mitochondria and thus prompt an overreaction of more mitochondria to be made. (Read more about metformin)

While mitochondrial dysfunction accelerates aging, we don’t yet know if improving mitochondrial function extends lifespan…

Stem cell exhaustion

Stem cells are the cells that can replenish your tissues. Basically, without stem cells regenerating tissues we get wrinkles, age spots, wounds that don’t heal, digestion doesn’t work very well, etc.

Telomere shortening can cause stem cell decline in some tissues.

Decreased production of adaptive immune cells causes a problem called immunosenescence.

Altered intercellular communication

Signaling between cells is vital for the overall health of an organ or tissue. Hormones are type of signaling molecule. For example, hormones produced in the brain control the release of cortisol from the adrenals. Elsewhere in the body, hormones can be produced to control things in the brain.

Inflammatory signaling molecules can be a big problem in the disease of aging. Low-level, chronic inflammation that isn’t related to an injury causes a variety of problems in aging.

Read more about chronic inflammation.


While this framework of 9 hallmarks of aging seem to be separate pillars, they all interact and come together in causing the diseases of aging, and perhaps aging as a disease.

Longevity Genes

There are several genes known as “longevity” genes. Specific variants of these genes have an association with an increased likelihood of living to be 100 or more. And…more importantly, these genetic variants have links to a longer ‘healthspan’.


The term longevity refers to lifespan. People in the US, on average, live to a little over 80 years of age, but some people live to 100+ and are still relatively healthy. You may immediately assume that everyone who lives longer did everything right- exercised, meditated, ate the very best diet, etc – but that isn’t necessarily the case. In fact, researchers estimate that about 25% of the variation in lifespan is due to genetics.[ref]

What does it take to live a long, healthy life? Avoiding smoking, not drinking too much alcohol, and not getting cancer are all important for the first 80 years. Beyond that, genetics becomes really important.

What if you don’t have the longevity gene variant? Understanding the genes involved in longevity points to some ‘lifehacks’ for increasing healthy aging for everyone. For example, there are supplements, such as green tea extract, that increase FOXO3.

What are the odds of living to 100?

Someone born a hundred years ago has less than a 1% chance of being alive today. In contrast, if you are female and born in 1973 (46 years old), your odds of living to 100 are 20%. (Here is a nice chart of your odds of living to 100 based on your birth year.)

Thus, if your odds of living to 100 are 20%, carrying a genetic variant that increases that doubles the odds is fairly significant! Retirement planning is a must.

Keep in mind, though, that while genetics does play a role in how long you live, there are lots of other health and lifestyle factors that are also important. This is just about statistics here.

What needs to go on at a cellular level for healthy aging?

Cells accumulate damage and their replacement happens all the time, at any age. The cells in your intestines turn over fairly quickly, with a cellular turnover rate of 2-6 days. Fat cells turnover every 8 years. In contrast, most brain cells never are replaced.[ref][ref]

When cells divide, the DNA needs to be copied correctly. Yep – mitosis, you learned about it in high school biology. Errors in the DNA copy mechanism occur, and if left uncorrected, the cell may need to go through apoptosis (cell death). DNA errors that occur in specific genes are what causes cancer…Avoiding cancer is important for longevity.

One way to increase lifespan in animals in a lab is to decrease calories. Numerous studies with lots of different types of animals have looked into calorie restriction — except for humans. A couple of the theoretical reasons for why calorie restriction increases lifespan include the changes to IGF1 (insulin-like growth factor 1) and autophagy.[ref] Autophagy is the cellular process of cleaning up damaged organelles and recycling cellular waste.

When it comes to the genetic variants linked with greater longevity, researchers show that genes involved in apoptosis, tumor suppression, regulating growth, and heart health are important.


Carrying the genes that increase my chance of living to 100 has changed my attitude and way of thinking about getting older. Planning for retirement suddenly became even more important!

Diets that increase FOXO3 and IGF1:

The Okinawan Diet is thought to promote healthy longevity, in part, by affecting FOXO3. The diet focuses on fresh vegetables, fish, lean meats, omega-3 fats, and unrefined carbohydrates.

Ketosis is theorized to decrease IGF1 and enhance FOXO3. Therefore, a ketogenic diet or intermittent/periodic fasting could increase longevity.[ref][ref]

Supplements that increase FOXO3:

Green tea polyphenols (EGCG) have found to increase FOXO3 levels.[ref]

Astaxanthin, naturally found in shrimp, salmon, and red algae can increase FOXO3 levels.[ref] If you aren’t getting enough astaxanthin from your diet, you can get it as a supplement.

Berberine, a supplement, is often used for blood glucose regulation. Research shows that it may enhance FOXO3A.[ref] You can get berberine as a supplement on Amazon or at your local health food store.

Genetic variants associated with longevity:

If you are interested in learning about your genetic variants, you can find them on here…Longevity and Genetics: FOXO3, CETP, IGF1, and more

(Originally published on

Nicotinamide Riboside and Nicotinamide Mononucleotide

(Note that this article is cross-posted from Genetic Lifehacks — more to some on this topic)

Nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) are two supplements that have taken the longevity and anti-aging world by storm. With animal studies showing exciting results including reversal of age-related diseases, these supplements are an exciting glimpse into the future of reversing aging.

Just a heads up, so that you aren’t disappointed: There is little research, as of yet, into the ways that genetic differences impact NR or NMN. Instead, I will dig into the science of how NR and NMN work, the research that has been done on NR and NMN, and then explain the connections with sirtuins, PARPs, and aging. I will also dig into genetic variants that impact the body’s production of NAD+ and the relation to sirtuin gene variants. But…I can’t tell you, based on your genes, whether you should take NR or NMN 🙂

Table of Contents


NAD+ (nicotinamide adenine dinucleotide) is an important molecule that all plants and animals produce and use. It is a niacin derivative used in all living cells for a bunch of different purposes. It is one of those ‘can’t live without’ type of molecules!

NAD+ in cellular energy production:

A quick overview of cellular energy production for those for whom high school biology is but a distant memory

In cellular metabolism, NAD+ is an essential part of energy production. When you eat food, your body converts it into the components needed by the cells for producing energy. For example, carbohydrates break down into simple components such as glucose. The glucose can then be directly used in the cells to produce ATP, which is the molecule your body uses for energy.

During cellular energy production, glycolysis uses glucose to produce a little ATP (net of 2 molecules) and acetyl-CoA. Then, the acetyl-CoA can be used in the mitochondria to produce more ATP via the citric acid cycle (aka Krebs cycle). Additionally, your body can convert fatty acids into acetyl-CoA when it is in ketosis.

NAD+ comes into play within the Kreb’s cycle, shuttling electrons between the NAD+ and NADH. The net result from the Kreb’s cycle is three NADH molecules (and one ATP).

Next up in energy production within the mitochondria is oxidative phosphorylation (electron transport chain). Within the inner membrane of the mitochondria, oxidative phosphorylation takes those intermediates of the citric acid cycle and cranks out a bunch of ATP (energy molecule). This is your body’s main way of producing energy when there is enough oxygen present. In fact, it is the main way that all aerobic organisms with mitochondria produce energy.

An essential step in this process uses NAD+ for the transfer of electrons.

Electron transport chain showing the process of producing energy in a cell. Image credit: public domain

Other roles of NAD+

While the use of NAD+ for cellular energy production is fundamental to life as we know it, this molecule is also used in numerous other reactions in the body.

NAD+ is consumed in the type of reactions known as ADP-ribose transfer reactions. Examples of this include processes such as the repair of DNA and in the maintenance of telomeres, the end caps of DNA that are important in cellular aging.

NAD+ is also used in reactions involving sirtuins. Sirtuins are a family of proteins (SIRT1 through SIRT7) that are essential for turning on and off the translation of genes within a cell. This is foundational for the control of cellular functions. (More on sirtuins to come…)

Additionally, NAD+ involves cell signaling processes both within and outside of cells.

Yep – I’ve used the words essential, foundational, and fundamental here, but these seem like a weak way to explain the necessity of NAD+ in your body.

Let me dive into all of these a bit further…

NAD+ and Aging:

As we age, there are a number of physiological changes that take place. You all know this — you lose your hearing and your hair, muscle mass declines, wrinkles increase, weight tends to rise, along with blood glucose levels. Eventually, you end up with heart problems or diabetes, and then everything goes downhill from there.

NAD+ levels decrease with age and could be at the heart of some of the age-related declines we face. For example, NAD+ is important in DNA repair, and this process is so important for preventing cellular death – or cancer. Mitochondrial energy production decreasing in aging is another big part of why everything goes downhill.

Sirtuins and Aging:

I mentioned above that sirtuins rely on NAD+, and that this is important in gene expression. Let me explain this further…

Sirtuins are a family of genes, SIRT1 through SIRT7. The function of all of them is not yet fully understood.

The regulation of gene expression involves sirtuins. Meaning, the sirtuins must cause the DNA in the cell nucleus to either be accessible or inaccessible for a gene to be transcribed. The ability for the regulation of genes transcribed into proteins is fundamental to cell function. Every cell nucleus contains the same DNA. The differences between a liver cell and a muscle cell are due to the regulation of which genes are transcribed. Thus, disrupting the sirtuins can lead to mucked up cell function and the symptoms of aging.

In the initial studies on the sirtuin genes in yeast, it was found that adding in additional copies of the gene increased lifespan by 30%. [ref] Think about what that could mean for humans — regularly living to 110 instead of 80?

SIRT1 codes for the sirtuin 1 protein. It involves sensing nutrient availability and thus linked to problems with insulin resistance. Studies show animals with insulin resistance have decreased SIRT1 levels. When researchers increase SIRT1 in animals, they are resistant to the problems of obesity and insulin resistance that a high-fat diet induces in them.[ref][ref] Researchers recently discovered that SIRT1 is also important in the development of the egg cell.[ref]

SIRT2 codes for the sirtuin 2 protein that is located in the cytosol of the cell. This important enzyme arranges the chromosomes for cell division in mitosis.

Sirtuins use NAD+ to complete their cellular activity, and it is through that the NAD+ levels may be a sensor for how much energy is available in an organism.[ref]

SIRT3, 4, and 5, found in the mitochondria, are important for oxidative stress and fat metabolism.[ref]

SIRT6 is important in gene expression for metabolic regulation, telomere maintenance, and mitochondrial respiration. Reducing Sirt6 in the liver causes animals to develop fatty liver disease, and knocking out Sirt6 altogether causes animals to die within a few weeks due to severely accelerated aging.[ref]

PARPs and NAD+

Another group of enzymes that consume NAD+ in their reactions is PARPs, which stands for poly(ADP-ribose) polymerase. PARPs are another family of proteins important in DNA repair and genomic stability. They can detect when the DNA breaks and signal for its repair. They can also initiate cell death when the DNA repair doesn’t occur. Again – vital cellular functions, especially in aging.[ref]

PPAR1 uses up a lot of NAD+ in the process, causing a decrease in ATP production for the cell. The DNA damage signal response enacts when DNA replication is poor.[ref] Cell death is necessary, in the right context, but excessive cell death, especially in the brain, is not good.

Excessive DNA breakage can lead to a lot of PARP activation, thus depleting NAD+. What causes DNA breakage? UV light, reactive oxygen species (oxidative stress), lipid peroxidation, and a number of different environmental toxicants. DNA damage occurs all the time in the normal course of cell replication. Thus the importance of DNA damage repair systems in the body.

PARP1 can initiate cellular repair for single-strand DNA breaks. This is important in longevity.

Inhibiting PARP is a way to mitigate the decreased NAD+ and ATP levels and decrease cell death. It doesn’t fix the cause (DNA breakage), but it puts a bandaid on the downstream effects of PARP activation. Atherosclerosis and congestive heart failure are two diseases in which PARP inhibitors might be used. The inflammation within the vascular cells causes PARP1 activation and the subsequent decrease in NAD+ and cellular energy. Inhibiting PARP then slows the inflammatory response and preserves the ATP and NAD+ in the cells of the heart.[ref]

The flip side of inhibiting PARP would be to have plenty of NAD+ available for the rest of the heart cells. Animal studies using a mouse model of sepsis show that, indeed, giving nicotinamide riboside, which increases NAD+, protected the heart and lungs from injury and decreased death due to sepsis.[ref]

Creating NAD+ in the body:

Precursors of NAD+ include different forms of niacin (vitamin B3) and tryptophan. The different forms of niacin, whether from food or from supplements, are nicotinamide (aka niacinamide) and nicotinic acid (niacin). The nicotinic acid form (niacin) is the one that can cause flushing when taken in larger doses.

Foods that are high in niacin include tuna, chicken, beef liver, salmon, and pork. Non-meat sources of niacin include brown rice, peanuts, and potatoes. What doesn’t have niacin?…corn that hasn’t been nixtamalized (processed with limewater). A lack of niacin causes a disease state known as pellagra. Thus, in the late 1800s and early 1900s when people in the US South were dependant on corn for most of their calories, there was an epidemic of pellagra. Symptoms of pellagra include dementia, diarrhea, and a skin rash.

Tryptophan, found in a lot of protein-containing foods, is an essential amino acid. Your body can also convert tryptophan into niacin through the kynurenine pathway. However, this pathway to form niacin isn’t utilized by the body as much as obtaining niacin from foods that contain it.

Another way to create more NAD+ is by converting nicotinic acid. The first step converting nicotinic acid to NA mononucleotide uses the NAPRT enzyme coded for by the NAPRT gene.[ref][ref]

NR and NMN:

Both nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) are important in the creation and recycling of NAD+.

NMN, synthesized from nicotinamide (niacinamide) and PRPP (5’-phosphoribosyl-pyrophosphate), uses the enzyme NAMPT.[ref

NR is another precursor of NAD+ and found in low levels in foods, particularly in milk.

NAD+ doesn’t have to be synthesized continually from the precursors — it can be recycled through the “NAD Salvage Pathways”. Reusing the components of NAD+, specifically nicotinamide, is your body’s main way of having enough NAD+ available in all cells. This salvage pathway uses the supplemental NR and NMN in the body.

Studies on NR and NMN:

Enough background science – let’s get into the interesting research on supplemental nicotinamide riboside and nicotinamide mononucleotide.

Animal studies on NR and NMN:

Here are some of the animal studies on NAD+ precursors that are exciting:

Alzheimer’s: In a mouse model of Alzheimer’s disease, NMN shows the restoration of mitochondrial function in the brain. The oxygen consumption deficits in the brain mitochondria, found in Alzheimer’s showed a reversal. Again, this is a mouse study… but pretty cool.[ref]

Hemorrhagic shock: In a rodent model of hemorrhagic shock, those receiving NMN had less inflammation and better cellular metabolism. Both of which increase survival in hemorrhagic shock.[ref]

Aging: Nicotinamide riboside (NR) was fed to old mice for three months. The NR decreased several of the signs of aging in the mice such as altered fat mass, cholesterol levels, and liver enzymes.[ref]

Fatty Liver Disease: Quite a few studies show that NR can reverse fatty liver disease.[ref][ref][ref]

Cognitive Function: Another mouse study showed that NR could improve cognitive function in a mouse model of diabetes. Not only did cognitive function improve, but inflammatory markers in the brain reduced, as did amyloid-beta.[ref]

Hearing Loss: NR was protective in mice from age-related noise-induced hearing loss. This was through increasing SIRT3 expression.[ref]

Offspring: For postpartum mouse moms, NR was beneficial. It increased lactation, nursing behavior, and transmission of micronutrients to mouse babies. Those offspring grew up to have advantages “in physical performance, anti-anxiety, spatial memory, delayed onset of behavioral immobility, and promotion of adult hippocampal neurogenesis”.[ref]

Mitochondrial Function: A mouse study also found that NMN could dampen the DNA damage response and improve mitochondrial function. It also helped with liver damage.[ref]

Increased Lifespan: A small increase in lifespan (about 4%) has been shown in mice that were fed NR starting in old age.[ref]

Restored SIRT1 Levels: Middle-aged mice fed NMN showed increased Sirt1 levels, similar to younger mice.[ref]

Human studies on NR and NMN:

Safety first: A study looked at the safety of NR (Niagen brand) in healthy men and women over a course of 8 weeks. They used doses ranging from 100 to 1000 mg. All doses increase NAD+ metabolites within 2 weeks, and it was dose-dependent (high doses= high NAD+). Most importantly, there were no differences in adverse events between the NR groups and the placebo group. This study also noted that the NR did not mess up methylation.[ref]

In another trial, 2,000 mg/day of NR in obese, sedentary men aged 40 – 70 was safe (12-week study). But it didn’t show any miraculous effects on insulin sensitivity, glucose disposal, or resting energy expenditure.[ref] In other words, the fabulous metabolic results seen in mice didn’t happen in obese, older men. Or at least the markers that they were looking at (HbA1C, glucose, cholesterol, triglycerides) didn’t change much.

Boosting NAD+: A short, small study examined the effects of NR on healthy volunteers for 9 days. The study participants took 250 mg for the first two days and then titrated up to 1000 mg. On day 9, NAD+ levels had increased by 100%. No NR supplement side effects were reported. Interestingly, most of the individual response curves were similar in the percentage increase, but there were a couple of participants that had a much bigger response.[ref]

Decreased Inflammation: A study of ‘aged men’ looked at the effects of supplementing with 1,000 mg of NR per day for 3 weeks. The results showed an elevation of NAD+ in the muscles and a decrease in inflammatory cytokines levels.[ref]

Heart health: A study that included 30 middle-aged and older men and women looked at the effect of NR vs placebo for six weeks. Oral NR supplementation (1,000mg/day ) raised NAD+ levels by 60% compared to placebo. NR lowered blood pressure and aortic stiffness (a little). Notably, the participants who had stage one hypertension, to begin with, had a 10 point drop in systolic blood pressure. One drawback, in my mind, for this study, is the participants took the placebo or NR for six weeks – and then swap for the next six weeks. Then the comparison of the data was done for the placebo vs. NR. It seems like there should have been lasting benefits from the group initially taking NR and then switching to the placebo group, thus masking some of the statistical differences.[ref]

The human studies are nice from a safety point of view, but more studies are needed on larger groups for longer time periods. Several clinical trials are in the works right now, so hopefully, we will have more answers soon!

Niacin/NR/NMN from food:

Some studies indicate that 20mg of niacin can meet our need for NAD+ biosynthesis. The US government’s daily requirement of niacin is 12 mg and seems to be the amount needed to prevent pellagra. The RDA is set at 16mg/day.[ref]

Broccoli and cabbage contain up to around 1mg/ 100 gm of NMN. Avocados and tomatoes have also shown to contain NMN in the .36 to 1.6 mg/100 grams range. So while food can be a minor source of NMN, body synthesis is more common than obtaining it through the diet.

Tryptophan can also eventually end up as NAD+. But it takes 60-times the amount of tryptophan compared to niacin to get to nicotinic acid mononucleotide (NAMN). Tryptophan can help to prevent pellagra (niacin deficiency), but it isn’t the main source for most people today.[ref] (Read about tryptophan and the kynurenine pathway genes)

Methylation cycle and nicotinamide:

Not all nicotinamide converts back to NAD+. Some of it can degrade through a methylation-dependent pathway. The NNMT (nicotinamide N-methyltransferase) enzyme is key to the reaction between nicotinamide and SAMe.

A mouse model created to have too much of the NNMT enzyme was used for testing the link with fatty liver disease. Mice that produce extra NNMT were fed a high-fat diet and nicotinamide. They had accelerated fatty liver disease.[ref]

Circadian Rhythm and NAD+

I’m sure that most of you who have read a few of my articles have noticed that circadian rhythm is a theme that runs throughout genetics and health. There’s no escaping the fact that circadian rhythm controls so much of what goes on in our bodies. Kind of like the cycle of sunlight and darkness governs all living organisms.

The core molecular circadian clock is driven by the rising and falling levels of four genes: CLOCK and BMAL1 rise and then are suppressed as PER and CRY accumulate. The CLOCK gene expression is controlled by a sirtuin (SIRT1), which is in turn dependant on NAD+ levels.[ref]

I know – you all are thinking, “holy crap! mind blown!” right now. Or you are wondering how deep in the weeds this article will wonder:-)

Let me connect a few dots…NAD+ levels are needed for the sirtuins to work. The sirtuin family of proteins controls whether a portion of the DNA is available to be transcribed – or not. Like a light switch turning on or off.

SIRT1, important for the core circadian clock gene (aptly named CLOCK) to function correctly, rises and falls over the course of 24 hours.

A connection exists between the disruption of the core clock genes and the various chronic disease states associated with aging, such as diabetes, heart disease, obesity, metabolic syndrome, and Alzheimer’s disease.

Thus, one mechanism by which low NAD+ levels impacts us as we age is through altered CLOCK gene expression.

SIRT6 also shows control of the liver’s clock – separately from SIRT1. This leads to the control of lipid metabolism in the liver.[ref]


Supplements to boost NAD+

Nicotinamide riboside (NR) is patented and made by ChromaDex in the US. It is called (Niagen) and sold as TRU Niagen. Also included in Thorne ReveraCel (coupled with resveratrol and quercetin) and in the Life Extension formula NAD+ Cell Regeneration (which seems to be way overpriced on Amazon – check around for better prices!).

NR can also be found in the supplement called Basis made by Elysium. It now contains a formulation of NR that is proprietary to Basis. Lots of research (and marketing…) has been done by the developer of Basis, so it may be worthwhile to check out. You have to order directly through the company.

NMN is also available as a supplement. There are several options on Amazon, including GeneX NMN and Mastermind NMN.

Resveratrol is an activator of SIRT1.[ref] Some people stack resveratrol with NR to boost the effects of SIRT1.  Resveratrol is available on Amazon or at any local health food store (or grocery store).

Pterostilbene, a polyphenol found in blueberries and an analog of resveratrol, is an activator of SIRT1.[ref] [ref] The nicotinamide riboside supplement BASIS includes pterostilbene. It is also available as a stand-alone supplement on Amazon, or you can eat a lot of delicious blueberries.

Tryptophan is a precursor, albeit a minor one, for the synthesis of NAD+. Even though it is a minor player, it is important to get enough tryptophan in your diet. Most foods that contain protein also contain tryptophan, so people generally get plenty of tryptophan if they eat a varied diet. Foods that contain a lot of tryptophan include cheese, chicken, fish, eggs, beef, pork, beans and lentils.

Don’t want to take supplements?

There may be other ways to reap the NAD+ benefits:

Exercise…It seems that everyone (including me) always recommends exercise for pretty much every health topic. A recent study showed that one way that exercise is beneficial in aging is that it stops the decline in the enzymes needed for NAD+ production. In older people (age 55+), aerobic exercise increased NAMPT.[ref]

Fasting has shown to increase NAD+ levels.[ref]

Methylation cycle worries?

Some clinicians seem worried about supplemental NR decreasing methyl groups in the body. One small human study did not find an effect on methyl groups[ref], but individual genetic differences may make this an issue for some people. If this is a problem for you, increasing your methyl donors may help. Choline (from eggs, liver, sunflower lecithin) and folate (from broccoli, legumes, leafy greens) can help increase your supply of methyl groups. Supplements that increase methylation include SAMe, TMG, and methylfolate.

Genetic variants:

Interested in your genetic variants? You can find them on here…Boosting NAD+ to Reverse Aging? Overview of NR and NMN

Advanced Glycation End Products

(Note that this article is cross-posted from Genetic Lifehacks)

Recent research shows that advanced glycation end products (AGEs) are a causative factor in many degenerative diseases – including almost all of the diseases associated with aging. AGEs have links to Alzheimer’s, heart disease, diabetes, chronic kidney disease, wrinkles and loss of skin elasticity, and more.

Like most topics covered here on Genetic Lifehacks, both genetic susceptibility and lifestyle interact to cause the problems associated with AGEs. This article will dig into genetic susceptibility and then discuss the lifehacks that can help to mitigate any susceptibility. In fact, one specific type of advanced glycation end product has shown to be highly determined by genetics.[ref]

Table of Contents

Advanced Glycation End Products:

The term AGEs (advanced glycation end products) refers to a lipid or protein being glycated, which means that a sugar or aldehyde binds with the protein or lipid. It is a general term that is applied to a bunch of different molecules, but the basic premise is that certain byproducts of glycolysis (producing energy from sugar) can bind with a protein or fat in the body and alter it permanently.

AGEs naturally occur in the body as a result of normal metabolism. You can also consume AGEs in foods,  and their production can depend on how you cook the food.

The problems with advanced glycation end products develop when an excess is produced by the body, along with consuming a diet high in AGEs.

First, a quick food example of AGEs to give you a picture of what is going on…When you throw a steak on the grill or brown a pork chop in a hot pan, advanced glycation end products form in the process of browning the meat. Known as a Maillard reaction, it is what makes grilled meat and vegetables taste great and smell delicious. This Maillard reaction is producing advanced glycation end products in the food. Think about uncooked bacon versus the taste, feel, and smell of cooked bacon – a big part of the deliciousness is the production of AGEs. It also causes the proteins to transform, linking together to create nice, crispy bacon.

Grilled meat makes a great mental image, but AGEs also form within the body under normal conditions. In fact, the majority of advanced glycation end products come from this natural formation process in the body rather than from food.

So let me go into the formation of AGEs in the body first and then discuss ways to prevent the formation of AGEs in foods in the Lifehacks section at the end.

Where do advanced glycation end products come from in the body?

Glucose is the main fuel that your body uses for energy. (Yes, you can use fat for energy also if you are in ketosis. Stick with me here, even if you are a low carb fanatic.)

We get glucose from consuming carbohydrates and our body breaks them down into simple sugars. The body can also create glucose via a process called gluconeogenesis, but this isn’t a big source of glucose under normal circumstances.

Inside all of your cells, glucose converts into energy in the form of ATP.

When glucose is used in the cell for glycolysis, it goes through a multistep process to break the glucose molecule (C6H12O6) into two pyruvate molecules plus a hydrogen ion. This process releases energy that is stored in the ATP molecule. In high school biology, it is usually just noted that glycolysis is the process of splitting the glucose molecule, forming two pyruvates and two ATP. But there are actually a bunch of intermediate steps along the way.

One of the intermediate steps of glycolysis forms glyceraldehyde-3 phosphate, which can spontaneously form methylglyoxal (MGO). Methylglyoxal is a ‘key precursor of the AGEs’.[ref]

Why are AGEs a problem?

The body has a hard time getting rid of advanced glycation end products. When a protein is bound to a carbohydrate, its structure is altered in such a way that the enzymes that would normally act on the protein can no longer break it down. Thus, the altered proteins can build up in the body.[ref]

Getting rid of AGEs is especially a problem in collagen and elastin, which have a slow turnover rate. It is also a problem when glycated proteins cross-link and form large proteins. The proteins have to be eliminated, mainly through the kidneys.

Another reason that AGEs are a problem is that they can stimulate the AGE receptor (known as RAGE), which signals for a cascade of inflammatory events.[ref]

Three problems with AGES: 1) they can build up because they are hard to eliminate; 2) they trigger inflammation through their receptor; 3) they cause protein structure to be altered.

AGEs as a causal factor of aging

If you consider aging a disease, then it makes sense to look for the causes of that disease called aging. In general, aging usually involves a loss of fitness – low muscle mass, easy injuries, increased risk of chronic diseases. These all tie together with the increased cellular damage that happens over time. This accumulated cellular damage then causes a bunch of problems — including excess AGEs.[ref]

It can be argued that one of the causal factors of aging is your body accumulating more and more advanced glycation end products. AGEs = Aging.[ref]

For example, I mentioned AGEs forming in collagen above…Collagen is a protein that is an abundant component of bones, ligaments, skin, and muscles.

When AGEs accumulate in the collagen proteins in joints, muscles, and bone, they play a role in causing arthritis, muscle loss, and osteoporosis. All are associated with both aging and higher levels of AGEs.[ref]

The cross-linked proteins, such as in collagen in a tendon, can increase stiffness and make it more prone to tearing. Think about the problems of a twisted ankle with a tendon tear when older vs when you were a kid.[ref]

This increased cross-linking in AGEs also shows up in the skin. As AGEs increase with age, you get wrinkles, thinner skin. and less elasticity.[ref]

What causes excess AGEs in the body?

More AGEs are produced under conditions of oxidative stress. When too many reactive oxygen species (ROS) are present in a cell, it causes oxidative stress. Not only does this trigger the body’s antioxidant defenses to be produced, but the excess ROS can also escalate the production of the precursors for AGEs. This happens through increased lipid peroxidation and glycoxidation reactions, which causes more of the reactive products (like methylglyoxal) that bind with proteins to form AGEs.[ref]

More AGEs are also produced when blood sugar levels are high. Diabetes is a disease of high blood glucose levels. This excess of glucose makes it more available and thus likely for AGEs to form. A lot of the complications of diabetes, such as cardiovascular disease, retina problems, and kidney problems, are actually caused by the accumulation of AGES.[ref]

Preventing the formation of AGEs in the body:

The glucose metabolites that react to form AGEs can be stopped by multiple ways in the body. In fact, the body naturally has several ways to combat AGEs, and the key is to promote this along with decreasing production.

The enzymes glyoxalase I and II are tasked by the body to break down methylglyoxal, one of the main precursors for the production of AGEs in the body. Methylglyoxal forms as a side-product during glycolysis.

Decreased levels of glyoxalase I (GLO1 gene) have associations with higher AGEs in the plasma of hemodialysis patients. Another study found that upregulating the GLO1 gene (animal study) prevented AGEs formation in the presence of high blood glucose levels.[ref]

What does it take to make glyoxalase? Glutathione, one of the body’s main antioxidants, is a cofactor of glyoxalase. Low levels of glutathione can reduce the activity of glyoxalase 1.[ref]

Taking this one step further, the Nrf2 pathway stimulates glutathione production in the cells. It has shown in recent studies that activating the Nrf2 pathway can stop the formation of AGEs by eliminating methylglyoxal.[ref]

Often when thinking of advanced glycation end products the mind jumps to the idea that eating sugar is entirely to blame: Glycolysis is a glucose-based pathway and the side-products of glycolysis (especially methylglyoxal) increase AGEs. High levels of glucose in the blood do increase AGEs. But one of the ketone bodies formed when eating a low-carb diet is acetone, and acetone can also be converted using the CYP2E1 enzyme into methylglyoxal.[ref][ref]

AGEs and RAGEs…

Essentially, we have two things going on here with AGEs.

First, we don’t want a build-up of AGEs in general. They are hard for the body to get rid of, and they are making my skin look old. In a general sense, we can prevent this by keeping glucose levels low and boosting glyoxalase.

Second, we don’t want a lot of AGEs to bind with the receptor for advanced glycation end products (RAGE), which causes inflammation. (more below on this…)

Genetics comes into play here, with some people having more of a problem with this than others. In other words, some people who have genetic variants in the receptor for AGEs are going to be more susceptible to the negative consequences of AGEs.


RAGE stands for the receptor for advanced glycation end-products. It is coded for by AGER gene. When AGEs bind to the receptor, it triggers inflammation.

RAGEs are called a multi-ligand receptor, meaning multiple molecules can bind to it. They are located on the cell membrane in a bunch of different cell types including endothelial cells, immune system cells, muscle cells, and neurons.

RAGEs and Inflammation:

When AGEs (or another molecule) activate a RAGE receptor on the cell membrane, it transmits a signal that increases the body’s immune response. For example, in endothelial cells, which line the blood vessels, activation of the RAGE receptors causes the expression of the proinflammatory cytokines IL-1a, IL-6, and TNF-alpha. It also causes the formation of proteins needed for clotting, vasoconstriction, and cellular adhesion. [ref] This all adds up to inflammation in the blood vessels, higher blood pressure, and cardiovascular disease.

Diseases associated with RAGE activation include “inflammatory diseases, rheumatic or autoimmune diseases, infectious diseases, diabetes, metabolic syndrome and its complications, obesity, insulin resistance, hypertension, atherosclerosis, neurological diseases such as Alzheimer’s disease, cardiovascular diseases, pulmonary diseases such as chronic obstructive pulmonary disease (COPD), and cancer.”[ref] (Yes, that is pretty much every chronic disease that I can think of — and all are associated with aging.)

Activation of RAGE (cell membrane receptor) causes an increase in reactive oxygen species as well as the increase in inflammatory cytokines.  It also downregulates the cholesterol transporters, ABCA1 and ABCG1. This is important in neurodegenerative diseases.[ref]

RAGEs and Glyoxalase-1 interact:

As I talked about above, the enzyme glyoxalase breaks down one of the precursors for AGEs (methylglyoxal). Researchers have found that the receptor for advanced glycation end products also regulates glyoxalase. In animal studies, when the researchers delete the RAGE gene (AGER gene), the animals no longer accumulate methylglyoxal.[ref]

RAGEs in Alzheimer’s:

I mentioned above that RAGE is a multi-ligand receptor, which just means that there are multiple molecules that can bind to it. In addition to AGEs, amyloid-beta is another molecule that can bind to RAGE. Amyloid-beta, produced in the brain, and its accumulation is one of the hallmarks of Alzheimer’s disease.

The inflammatory signaling from binding with RAGE exacerbates the neurodegeneration in Alzheimer’s disease. Glyoxalase 1 initially upregulates in the early stages of Alzheimer’s. But eventually, due to glutathione depletion, the overall activity of glyoxalase 1 reduces.[ref]

Soluble RAGEs:

There are two forms of RAGE, a soluble and a full-length form that is the receptor on the cell membrane. In contrast to the membrane receptor form, the soluble form of RAGE doesn’t signal for inflammation. Possibly, soluble RAGE acts as a decoy receptor and is protective against the accumulation of amyloid-beta.[ref][ref]

One example of how soluble RAGE acts to decrease AGEs can be found in osteoarthritis. People with osteoarthritis have significantly lower levels of soluble RAGE in their synovial fluid (fluid in the joint).[ref]

Basically, you want more of the soluble form of RAGE. If soluble RAGE is floating around, it can bind with AGEs (or other molecules) and prevent them from binding to the RAGE receptor that is on the cell membrane which activates inflammation.[ref]


The big question here is…

How do you lower advanced glycation end products?

There are several ways to decrease AGEs both through the way that you cook your food, balancing your blood glucose levels, and boosting your body’s natural detoxification system.

Also… never smoke. Tobacco smoke increases AGEs in the lining of the arteries, LDL cholesterol, the lens of the eye, and collagen in the skin. Basically, one reason smoking causes wrinkles, high blood pressure, and cataracts is due to increased AGEs.  Second-hand smoke is also a problem.[ref][ref]

Dietary choices to decrease consumption of AGEs:

Foods high in AGEs include meats cooked with high, dry heat. Going beyond steak or grilled chicken, AGEs also form in any food that contains proteins and fats and is browned. Cheese also contains higher levels of AGEs. One study explains that the ‘order of dietary AGEs levels in foods is found to be beef>cheeses>poultry>pork>fish>eggs’.[ref] Lower amounts of AGEs are found in uncooked foods and cooked fruits, vegetables, and whole grains. Milk is also low in AGEs (but cheese is high).  In addition to broiled meats, oils heated to a high temperature and roasted nuts also are high in AGEs.[ref]

Studies show that AGEs partially absorb in the intestines from foods at a rate of 10 – 30%. The studies, though, are only looking at some of the AGEs in foods because it is difficult to figure detect and quantify all of the different types.[ref]

Carbohydrates generally contain the lowest amount of AGEs.[ref] But…carbs also tend to increase blood glucose levels the most. Finding a balance between foods that are low in AGEs yet don’t spike your glucose levels is important.

Carbohydrates such as bread heated to the point of browning have higher AGEs in the browned portion (the crust).[ref] Perhaps those picky kids who don’t eat the crust on bread actually have the right idea.

If you are a soda drinker, the types of soda with caramel additives (brown sodas, like Pepsi and Coke) have higher levels of AGE precursors than clear sodas (like Sprite).[ref]

Putting this into practice:

  • Cut back on the grilled meat and foods cooked at high heat.
  • Swap out some of your grilled recipes for crockpot (low and slow) recipes.
  • Eat more vegetables, cooked or raw.
  • Decrease or eliminate fried foods, and don’t go overboard on roasted nuts.
  • Combine your grilled or pan-fried meats with foods high in polyphenols (e.g. have some Broccoli slaw alongside your BBQ).
  • Consider sous-vide for your steaks? Or perhaps the reverse sear method (and go light on the sear!)

Polyphenols and supplements that block the formation of AGEs:

Just as there are different types of AGEs, different natural compounds that block the formation of specific AGEs in the body. Your best bet may be to stack multiple ways of blocking the formation of AGEs in the body — along with a diet that is low in AGES.

Berberine, a plant-based supplement, is known for lowering blood glucose levels. It has shown in animal studies to inhibit AGEs formation.[ref] You can get berberine on Amazon or at your local health food store.  Note that it may also reduce blood pressure a bit – something to keep in mind if you are already on medication for high blood pressure.

Quercetin is a natural compound found in fruits and vegetables. It has shown in animal studies and cell studies to decrease the formation of AGEs.[ref] Quercetin has also shown in animal studies to increase GLO1 (glyoxalase 1) levels and also increase glutathione levels.[ref] You can get quercetin as a supplement in addition to consuming it in foods. Studies show that quercetin doesn’t absorb well as a supplement, but adding a little fat to it may help absorption.[ref]

Resveratrol decrease RAGE expression in diabetic rats.[ref] It also helps decrease AGE accumulation in diabetic rats.[ref] The dosages of resveratrol were higher than what you can get from drinking wine…(I know that you were thinking that you would just have some wine alongside your grilled steak.) It is available as a supplement. Note that it can also decrease blood pressure.

NAD+ boosters, such as nicotinamide riboside (NR) and NMN, may protect against the damage caused by AGEs.[ref] You can read all about NAD+, genetics, and why I think it is important here. NR (combined with resveratrol) or NMN is available on Amazon or at other health food stores.

Glutathione is a cofactor of glyoxalase 1. Your body naturally produces glutathione as an antioxidant. You can get it as a supplement or work on activating the Nrf2 pathway.

Sulforaphane, found in broccoli sprouts and cruciferous vegetables, has shown to reduce the production of advanced glycation end products.[ref] You can get high levels of sulforaphane from growing broccoli sprouts or via a supplement.

Aspirin reduces RAGEs. This may be one way that low-dose aspirin is protective against heart disease.[ref][ref][ref]  If you have questions or concerns about aspirin, talk with your doctor.

Curcumin and Gingerol have shown in a mouse study to decrease the effects of AGEs in muscle cells. Curcumin works through trapping methylglyoxal.[ref][ref] Eat your curry with some ginger?

Hesperidin, a flavonoid found in citrus fruits, helps upregulate glyoxalase 1. It does this by activating the Nrf2 pathway.[ref] You can get hesperidin as a supplement.


Studies in rats show that exercise helps to decrease AGEs in old rats. But the human studies show conflicting results on whether exercise is beneficial or not for AGEs.[ref] Some studies show staying active, in general, correlates with lower AGEs.[ref]

Sleep Well!

Perhaps as important as eating a diet with healthy vegetables is sleeping well. Getting adequate sleep was shown in a study of Japanese adults found that sleep deprivation may increase the formation of AGEs.[ref]

Men with sleep apnea have higher circulating levels of AGEs and insulin resistance.[ref] And sleep apnea also increases RAGE.[ref]

Genetic variants that impact RAGEs:

Interested in your genetic variants? You can find them on here…Advanced Glycation End Products