Diet to change the microbiome
Diet to change the microbiome
In the last few centuries, our diet has changed. The combination of advances in food technology and our preferences, led to us eating a lot of processed foods with high calorie density and less plant-based foods. Namely the intake of fibers has decreased dramatically. It is believed that our gut microbiota thrives on food that is not degradable for the host, like these fibers. So all this ultraprocessed food, with a high bioavailability for the host has led to a decrease in diversity of our gut microbiota, and a decrease in short-chain fatty acids (SCFA) production [1,2]. And as you now know, low diversity is consequently linked with poor health outcomes like obesity and diseases like IBD and the other diseases on this blog.
Metabolites from microbiota
The beneficial effects that are linked to
gut microbiota have been thought to be the effect of metabolites that are
produced by the microbes. Short-chain fatty acids (SCFA) are the most
well-known metabolites. Undigested dietary components like fibers get fermented
in the colon and converted into SCFAs by microbiota, mostly into butyrate,
propionate and acetate. These SCFAs play a role in important functions of the
intestine like motility, mucus production, epithelial barrier and immune
homeostasis. It is also seen that SCFAs show histone deacetylase (HDAC)
activity, which regulates the transcription of genes. This might be the bridge
between microbiota and immune and metabolic diseases [2]. Another important
role of the microbiota is the production of vitamins (K, B2, B9, B12). The
bacteria actually produce these for their metabolism, but the host takes them
up for its own benefit. [2]
SCFA and vitamins are the most well-known metabolites of the microbiota. But you can imagine that such a diverse group of microbes must produce a huge spectrum of metabolites, with a variety of effects. These effects are not limited to the host, but also influence the microbiome itself. Some of other documented metabolites are phytoestrogens, isothiocyanates, secondary bile acids and trimethylamine (TMA). This last one, also known as the 'fish odor molecule', has a less positive effect. This molecule derived from animal products like red meat, poultry and eggs has been associated with cardiovascular disease. [2]
What can diet do?
Changing the composition of your
microbiome does not have to take centuries. A large change in diet (like a
switch from a meat-based to a plant-based diet) can cause a shift in the
composition within 2 days [5]. This indicates that diet intervention can be
useful to target the microbiome in some situations. However, the effects of
dietary interventions vary considerably between subjects. These differences are
believed to be caused by the difference in composition and level of richness of
the microbiota between subjects [2, 4, 5]. This notion can be used to design personalized dietary
interventions based on the composition of one's microbiome.
There already have been some trials with personalized nutrition, where they were able to successfully predict postprandial glycemic responses in a cohort of 100 subjects given different meals. They were able to do this with an algorithm that took blood parameters, dietary habits, anthropometrics, physical activity and microbiota into account. This could be used to provide an accurate diet for for example DMII patients to prevent high glycemic responses after meals [6].
Who is doing it right?
It is widely recognized that diet plays a
big role in shaping the gut microbiota. One study showed that adherence to a
specific diet, the Mediterranean diet, promoted a specific composition of the
gut microbiome. This diet is characterized by a high intake of fruit,
vegetable, legumes, nuts, fish and low intake of saturated fat, meat and dairy
products. High adherence to this diet showed higher concentration of fecal
butanoic, propanoic and acetic acids (SCFAs).
It also showed that
plant-based diets (vegetarian, vegan) had a different microbiota signature than
meat-based diets, with more of the Lachnospira
and Prevotella genera. Meat-based
or omnivore diets had more of the genus L-Ruminococcus.
However, regardless if the subjects where vegetarian, vegan or omnivore, the
higher the adhere to a Mediterranean diet the higher the SCFA production. In
contrast, a low adherence to the diet was associated with higher urinary TMAO
levels, which was associated with cardiovascular disease [4].
Written by Pepijn Gossink
Posted on 14 oct 2018
[1] Ercolini D, Fogliano V. Food design to feed the human gut microbiota. Journal of Agricutural and Food Chemistry 2018
[2] Derrien M, Veiga P. Rethinking diet to aid human-micro symbiosis. Trends in Microbiology 2017
[3] Kashyap PC, Chia N et al. Microbiome at the frontier of personalized medicine. Mayo Clinic 2017
[4] De Filippis F, Pellegrini N et al. High-level adherence to a mediterranean diet beneficially impact the gut microbiota and associated metabolome. Gut 2016
[5] Sonnenburg JL, Bäckhed F. Diet-microbiota interactions as moderators of human metabolism. Nature 2018
[6] Zeevi D, Korem T et al. Personalized nutrition by prediction of glycemic responses. Cell 2015