Nowadays there is a lot of discussion about the gut microbiome and its importance to health. The big question is: can we feed, nurture, and improve our gut microbes through our diet alone, or do we need to take daily prebiotic and probiotic supplements?

The gut microbiome (microbial community) is incredibly important to our health. There are hundreds of species of microbes (bacteria, fungi, viruses) living in the gut, which is the intestines or gastrointestinal tract. The gut microbes are important for proper immune system function, for getting nutrients from foods, protecting us from pathogens (harmful microbes), and helping maintain the mucosal barrier of the intestines.

Research finds that eating real foods is the most important thing one can do for gut health. It is not taking daily prebiotic and probiotic supplements.

What are prebiotics and probiotics? Do I need to take them daily for gut health?

Research finds that the best way to feed gut microbes and for gut health is to eat real foods, not daily use of supplements. Both prebiotics and probiotics can be easily obtained from foods.

Prebiotics are “nondigestible substances” (fiber that can’t be digested) that act as food for gut microbes. They stimulate the growth or activity of certain healthy bacteria that live in the body. Prebiotics are present in fiber rich foods such as whole grains, fruits, and vegetables.

Probiotics are foods or supplements that contain live microorganisms intended to maintain or improve the "good" bacteria in the body. Foods that contain probiotics include yogurts, sauerkraut, kimchi, kefir, pickles, some dairy foods, miso, and some cheeses (e.g. cheddar, mozzarella).

Advertisers would have you believe that gut health can only be achieved through daily use of probiotic or prebiotic supplements. However, this is not true. Studies are starting to find problems with long-term daily use of probiotics.

A healthy gut contains hundreds of species (bacteria, fungi, viruses), and taking megadoses of a few species (a probiotic supplement) can overwhelm the normal gut microbial community and damage the overall ecosystem.

A healthy gut is one with a greater diversity of species, not just some species. Recent studies have found decreased microbiome diversity in long-term daily probiotic users, as well as impaired microbiome recovery after taking antibiotics. 

What is a healthy gut?

While no one knows what exactly is the "best" or "healthiest" microbial composition of the gut, it does look like having diversity of bacteria is best. Both the diversity of microbes and the mix of microbes can make you healthier and more able to resist diseases and adapt to disturbances.

Some microbes are common to all people, some other microbes are found only in some people, and the proportion of microbial species can vary among people. We now know that certain gut microbes are linked to chronic inflammation and diseases (e.g. heart disease and some cancers), while other gut microbes are linked to health and the absence of inflammation.

In other words, the kinds of microbes living in the gut are associated with either health or disease. For example, higher levels of the beneficial bacteria Faecalibacterium prausnitzii is associated with health, but lower levels with inflammation and diseases.

 

What is the best way to improve, feed, and nurture the beneficial bacteria?

A person’s diet has a large effect on what microbes live in the gut. What a person eats (their general dietary pattern) feeds some species of microbes and not others, and this determines what lives in the gut microbial community.

Think of the saying: “You are what you eat” in reminding yourself that what you eat feeds bacteria, and that different foods feed different bacteria.

Bottom line: A person can change and improve the gut microbes simply by changing what that person eats. The goal should be to lower chronic inflammation by feeding and nurturing beneficial microbes linked to health.

By changing your dietary pattern or what you eat, changes can occur within a few weeks. But to maintain the microbial changes one must continue with the new dietary pattern.

The microbial communities in the gut also fluctuate for various reasons such as illness, smoking, exercise, and medicines, but diet seems to be key to the health of your gut microbial community.

Don’t feed bacteria linked to inflammation. Low fiber diets increase inflammation in the gut and body, while high fiber diets lower inflammation in the gut and body. It turns out that our modern Western style diet low in dietary fiber, refined grains, lots of meat, high fat foods, highly processed foods, and sugary drinks and desserts, feeds microbes that are linked to chronic inflammation and disease.

The CDC (Centers for Disease Control and Prevention) says that currently more than 50% of the daily calories of the American diet is from ultra-processed foods. These convenience foods (e.g. fast foods, packaged meals, and desserts) do not feed beneficial gut microbes, but instead feed microbes linked to chronic inflammation.

Feed bacteria that are linked to health. Beneficial microbes are nourished by real plant foods, which generally contain lots of fiber. A variety of foods is best, because they provide a variety of fibers and nutrients. A diet rich in real plant foods and fiber, such as fruits, vegetables, whole grains, nuts, legumes, and seeds, is linked to beneficial microbes and health.

Some Simple Steps to Feed and Nurture Beneficial Gut Microbes:

- Eat a diet rich in fruits, vegetables, whole grains, nuts, seeds, and legumes (beans). This gives you lots of nutrients and fiber.

- Eat more raw fruits and vegetables. Raw fruits and vegetables contain a variety of microbes. Some recent evidence suggests that bacteria in organic fruits (e.g. apples) may be especially beneficial.

- Cheeses, yogurts, and fermented foods (e.g. sauerkraut, pickles, kimchi) contain a variety of microbes. Each of these foods contains different microbes, so eating a variety (in moderation) is best.

- Eat more fiber every day. A variety of fiber foods every day and several servings at each meal, is best. Dietary fiber is found in fruits, vegetables, whole grains, legumes (beans), nuts, and seeds. Meat, dairy products, and seafood does not contain dietary fiber.

Dietary fiber or roughage is the indigestible portion of food derived from plants. There are two types of fiber: Insoluble fiber which doesn't dissolve in water and passes through the intestines (it provides bulking), and soluble fiber, which dissolves in water, and becomes a gel. Plant foods contain both types of fiber in varying degrees and both are beneficial.

The latest research suggests that over 25 grams of fiber daily for adults is best. One could take fiber supplements, but actual real foods have many more benefits, and also provide a variety of fiber sources.

- Eat as many organic foods as possible. There is much we don't yet know about pesticide residues on our foods. Pesticides are like antibiotics - they kill off microbes, both good and bad, and the current view is that pesticide residues in food may also possibly kill off some beneficial bacteria in the gut.

- Try to avoid or eat less of mass-produced highly processed foods, fast-foods, preservatives, colors and dyes, additives, partially hydrogenated oils, and high-fructose corn syrup. Read all ingredient lists on labels, and even try to avoid as much as possible "natural flavors" (these are chemicals concocted in a lab and unnecessary).

Even emulsifiers (which are very hard to avoid) are linked to inflammation and effects on gut bacteria. Titanium dioxide in nanoparticle form is frequently added to some foods and candies, and it may disrupt gut microbes and cause gut inflammation.