Can you permanently change your gut microbiome through diet?
Diet does indeed change your gut microbiome, but lasting change requires lasting adjustment of your dietary pattern; a temporary diet has only a temporary effect.
Diet changes your gut microbiome quickly, but whether those changes actually stick is a different question. If you switch radically to a fully animal-based or plant-based diet, the composition of species shifts within just a few days. A diet high in animal products allows bile-tolerant bacteria to thrive; a diet rich in plants and fibre favours fibre-processing bacteria. This shift is measurable and reproducible, but microbes that enter via food establish themselves only temporarily.
The 'type' of your gut microbiome -- broadly speaking, the overall balance linked to your eating habits over years -- is more stubborn. Following a different diet for ten days already shifts small things, but the big picture does not change that quickly. That pattern appears to be more connected to how you have been eating for years than to what you ate last week. Lasting change therefore requires lasting adjustment of your dietary pattern.
The first 1,000 days after birth are the period in which the gut microbiome is most malleable. Disruptions during that phase, through diet or environment, have been linked to a higher risk of inflammatory diseases, immune problems and obesity later in life. In adulthood, the microbiome is more stable and fundamentally harder to change. In older adults too, living environment plays a role alongside diet: people in a nursing home have a different microbiome composition than people living independently.
In people with irritable bowel syndrome, a low-FODMAP diet (which restricts fermentable carbohydrates) can reduce symptoms, but it also has a downside. It simultaneously lowers the number of beneficial bacteria and the diversity of the gut microbiome. Individual responses vary considerably. Experts therefore recommend not following this diet for longer than necessary and reintroducing foods in a stepwise manner.
The picture regarding artificial sweeteners such as sucralose and saccharin, and regarding colour and texture enhancers in processed food, is still unclear. Animal and laboratory research suggests effects on bacterial diversity, but short-term studies in humans show hardly anything at normal consumption levels. Whether long-term use does have measurable consequences for the human gut microbiome has not been sufficiently investigated.
All claims are based on 7 studies (PMIDs: 24336217, 21885731, 26785481, 39940404, 35458244, 37630837, 36677689). Most are observational or short-term experimental; no long-term RCTs on lasting microbiome change are available.
Can your gut microbiome influence how long you live?
There are clear associations between a healthy, diverse gut microbiome and older age, but whether that microbiome promotes longevity or is itself a consequence of being healthy has not yet been proven. For now, a varied diet rich in fibre is the most concrete tool for supporting your gut microbiome.
Does my gut microbiome change as I get older, and does it matter?
Your gut microbiome certainly changes as you get older, but whether that is harmful depends strongly on which direction that change goes. What you eat has a major influence on this, so that is a concrete area to pay attention to.
Does eating a varied diet help your gut bacteria?
Fermented products have the strongest evidence base for increasing gut bacterial diversity. Eating broadly varied meals also helps, but above all avoid heavily processed products containing emulsifiers such as CMC.
Can exercise improve your gut microbiome?
Moderate regular exercise demonstrably improves your gut microbiome, but you need to keep exercising because the effect disappears when you stop. Do not overdo it: very intensive training can actually put gut health under pressure.
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 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.