Gut health and the microbiome

There are hundreds of species of bacteria in your intestines, each of which plays a specific role in health and requires different nutrients for growth.

Generally speaking, a diverse microbiome is considered a healthy one. This is because the more species of bacteria you have, the more health benefits they may be able to contribute to a diet consisting of different food types can lead to a more diverse microbiome. 

Unfortunately, the traditional Western diet is not very diverse and is rich in fat and sugar. In fact, an estimated 75% of the world’s food is produced from only 12 plant and 5 animal species however, diets in certain rural regions are often more diverse and richer in different plant sources.

Fruits and vegetables are the best sources of nutrients for a healthy microbiome.

They are high in fiber, which your body can’t digest. However, certain bacteria in your gut can digest fiber, which stimulates their growth.

Beans and legumes also contain very high amounts of fiber.

Fermented foods have undergone fermentation, a process in which the sugars they contain are broken down by yeast or bacteria. 

Many of these foods are rich in lactobacilli, a type of bacteria that can benefit your health.

Research shows that people who eat a lot of yogurt appear to have more lactobacilli in their intestines. These people also have less Enterobacteriaceae, which is a type of bacteria associated with inflammation and a number of chronic conditions.

Whole grains contain lots of fiber and nondigestible carbs, such as beta-glucan. These carbs are not absorbed in the small intestine and instead make their way to the large intestine to promote the growth of beneficial bacteria in the gut.

Research suggests that whole grains can promote the growth of Bifidobacteria, lactobacilli, and Bacteroidetes in humans. 

In these studies, whole grains also increased feelings of fullness and reduced inflammation and certain risk factors for heart disease.

However, keep in mind that some research shows that gluten-containing grains — such as wheat, barley, and rye — may actually negatively impact gut health by increasing intestinal permeability and inflammation in some people.

Diets containing animal-based foods promote the growth of different types of intestinal bacteria than plant-based diets do. 

A number of studies have shown that vegetarian diets may benefit the gut microbiome, which may be due to their high fiber content.

For example, one small 2013 study found that a vegetarian diet led to reduced levels of disease-causing bacteria in people with obesity, as well as reductions in body weight, inflammation, and cholesterol levels. 

A 2019 review noted that plant foods are rich in specific nutrients that can increase levels of beneficial bacteria and decrease harmful strains of bacteria to support gut health 

However, it is unclear if the benefits of a vegetarian diet on the gut microbiome are due to a lack of meat intake or if other factors may also play a role.

Probiotics are live microorganisms, usually bacteria, that provide a specific health benefit when consumed.

Probiotics don’t permanently colonize the intestines in most cases. However, they may benefit your health by changing the overall composition of the microbiome and supporting your metabolism. 

A review of seven studies found that probiotics have little effect on the gut microbiome composition of healthy people. However, there is some evidence that probiotics may improve the gut microbiome in those with certain diseases. 

One review of 63 studies found mixed evidence of the effectiveness of probiotics in altering the microbiome. But the researchers noted that the probiotics’ strongest effects seemed to be in restoring the microbiome to a healthy state after it had been compromised.