Gut barrier & microbiome
Debbie is convinced that gut barrier function is essential for healthy aging. The mucosal layer shields the body from its own digestive enzymes, and animal research suggests that when it thins with age, the escaping enzymes damage organs (autodigestion). She points to emulsifiers and surfactants in processed foods, and possibly in supplement capsules, as a modern cause of that thinning. She also sees the microbiome as a metabolite factory: some microbes (like bifidobacteria) look protective, while others make compounds such as imidazole propionate that affect the heart and brain. Some new findings are counterintuitive, like microbes that seem helpful in youth becoming a problem in old age.
How it connects
In old rats, a thinning gut mucosal barrier let pancreatic enzymes such as trypsin and elastase escape and build up in the heart, kidney, lungs, liver, and skin.
A New Theory of Why We Break Down in Old AgeAnimal studies show emulsifiers and surfactants such as polysorbate 80, carboxymethylcellulose, and carrageenan thin the mucosal barrier or disrupt barrier function.
Autodigestion: Are Digestive Enzymes Breaking Down Your Body?Gut microbes convert dietary histidine into imidazole propionate, a metabolite that ties together atherosclerosis, insulin resistance, type 2 diabetes, and neurodegeneration.
A Gut Metabolite That Drives AtherosclerosisB. pseudocatenulatum declined with age across Chinese cohorts, and in old mice it or its metabolite 5-AVAB reduced inflammation and improved cognitive and motor performance.
Research Roundup: Gut Metabolite Reduces InflammagingIn mice, microbiome shifts with age impaired memory through vagus-nerve signaling, and higher levels of A. muciniphila reduced intestinal stem cell regeneration.
Your Gut Microbiome as a Cause of AgingSucralose changed the gut microbiome in a way that lowered arginine production and weakened T cell responses to cancer immunotherapy.
Gut Microbiome, Artificial Sweeteners, and Cancer ImmunotherapyInterventions, strongest evidence first
Everyday steps
- Remove packaged foods that contain emulsifiers and surfactants, and read labels on items like tortillas, cream cheese, ice cream, and condiments.Autodigestion: Are Digestive Enzymes Breaking Down Your Body?
- Try intermittent fasting or time-restricted eating to cut the time your intestines are exposed to digestive enzymes.Autodigestion: Are Digestive Enzymes Breaking Down Your Body?
- Eat a Mediterranean-style diet, which was associated with lower imidazole propionate and fewer bacteria that produce it.A Gut Metabolite That Drives Atherosclerosis
- Choose powdered supplements or gelatin capsules over cellulose-based vegetarian capsules to limit exposure to capsule ingredients that may affect the gut barrier.Longevity Supplements: How Many Capsules Are You Swallowing?
- Make homemade yogurt with added bifidobacteria, inspired by the supercentenarian's bifidobacteria-rich microbiome.My Current Supplement Stack for Longevity