Can your gut microbiome affect your cholesterol?
Your gut microbiome influences your cholesterol through bile acid conversion and the fermentation of fibres. Eating more fibre is the most concrete and safe step to take; supplements such as berberine are not yet sufficiently substantiated for daily use.
Gut bacteria convert bile acids, substances the liver makes from cholesterol. Through this conversion, the bacteria indirectly influence how the liver produces and excretes cholesterol. Disruptions in this system are associated with higher cholesterol levels and a greater risk of cardiovascular disease.
A key role is played by the enzyme bile salt hydrolase, which certain gut bacteria possess. Bacteria with this enzyme prevent bile acids from being lost through the stool. Less loss means the liver needs to convert less new cholesterol into bile acids, causing blood cholesterol to rise. On the other hand, there are also bacteria with the opposite effect: in a large observational study of more than 1,400 participants, Oscillibacter bacteria were found to be associated with lower cholesterol levels. In the lab, these bacteria proved capable of actively breaking down cholesterol. Whether this also directly reduces the risk of heart disease has not yet been proven.
Diet acts as an important intermediary. Gut bacteria ferment fibres into short-chain fatty acids. With low fibre intake, as in a typical Western diet, the gut microbiome changes in a way that is associated with higher LDL cholesterol and triglyceride levels. Eating more fibre can partly reverse this, although the causal evidence for this is not yet fully conclusive.
There are also supplements that attempt to influence cholesterol via the gut microbiome. Berberine, a plant-based substance at 500 mg per day, modifies the gut microbiome and inhibits genes involved in cholesterol absorption. However, the evidence in humans is still limited and long-term safety has not been sufficiently studied. Pu-erh tea contains a substance that, in mice and in a small human study, modified the gut microbiome and thereby lowered cholesterol levels. These are interesting findings, but not yet a basis for concrete recommendations.
Claims based on observational studies, animal models, mechanistic studies and several small human studies. PMIDS: 35792223, 29080339, 29080336, 38569543, 31672964, 34068353, 32353823.
Can your gut microbiome influence your risk of heart disease?
Your gut microbiome influences your heart health through metabolic by-products that can promote arterial hardening, high blood pressure and blood clots. The association is plausible, but how best to modify the gut microbiome to protect your heart has not yet been sufficiently proven: always discuss major interventions with your doctor.
Can your gut microbiome influence inflammation in your body?
Your gut microbiome can influence inflammatory processes throughout your body via the gut wall. Eating more fibre and exercising regularly are the most well-supported ways to influence this favourably.
Can your gut microbiome influence how long you live?
There are clear indications that the composition of your gut microbiome is associated with how long and how healthily you age, but whether modifying your microbiome extends your life has not yet been demonstrated in humans.
Can your gut microbiome affect your memory and concentration?
Your gut microbiome can influence your memory and concentration through several routes, but most of the evidence still comes from animal and laboratory research. What you can concretely do right now is support your gut health through diet, as direct supplementation or probiotics for cognition have not yet been sufficiently proven in humans.
Is my gut flora linked to being overweight?
Your gut microbiome is probably linked to excess weight through multiple mechanisms, but a proven causal relationship in humans is still lacking. A varied diet that supports your gut microbiome is worthwhile, but specific supplements for weight loss have not yet been proven effective.
Is there a real connection between your gut microbiome and your mood or brain?
There is a biologically plausible and, in animal research, robustly supported connection between your gut microbiome and your brain, but causality has not yet been proven in healthy humans. A varied, fibre-rich diet is the most concrete step you can take right now.