These small bacteria interact with every organ and system, including the brain, immune and hormonal systems, influence the expression of genes, largely determining our health, appearance and even food preferences. Maintaining a healthy microbiome is essential for both prevention and treatment of existing health problems – gastrointestinal disease, obesity, autoimmunity, food sensitivities, hormonal disorders, excess weight, infections, depression, autism, and many others. In this article Julia Maltseva, nutritionist, functional nutrition specialist, author and organizer of the microbiome conference, will talk about how food choices affect the intestinal microbiota, and therefore our health.

The microbiome and healthy longevity

Diet style has the greatest influence on microbial representation in the gut. Not all food consumed by us is suitable for the vital activity and prosperity of “good” bacteria. They feed on special plant fibers called prebiotics. Prebiotics are components of plant foods that are indigestible by the human body, which selectively stimulate the growth and increase the activity of certain types of microorganisms (mainly lactobacilli and bifidobacteria), which have a beneficial effect on health. Prebiotic fibers are not broken down in the upper gastrointestinal tract, but instead reach the intestine intact, where they are fermented by microorganisms to form short-chain fatty acids (SCFAs), which perform a variety of health-promoting functions, from maintaining intestinal pH to inhibiting the growth of cancer cells. Prebiotics are found only in certain plant foods. Most of them are in onions, garlic, chicory root, asparagus, artichokes, green bananas, wheat bran, legumes, berries. SCFAs formed from them help to reduce blood cholesterol levels, the risks of cardiovascular and tumor diseases. According to studies, switching to a diet rich in prebiotics has increased the proportion of beneficial bacteria. Eating predominantly animal foods increases the presence of bile-resistant microorganisms that contribute to the development of chronic inflammatory bowel disease and liver cancer. At the same time, the proportion of beneficial bacteria decreases.  

A high proportion of saturated fat significantly reduces bacterial diversity, which is a hallmark of a healthy microbiome. Without getting their favorite treat in the form of prebiotics, bacteria cannot synthesize the required amount of SCFA, which leads to chronic inflammatory processes in the body.

One recent study published in 2017 compared the gut microbiome of people who followed different dietary styles – vegan, ovo-lacto-vegetarian and traditional diet. Vegans have also been found to have more bacteria that produce SCFAs, which keep cells in the digestive tract healthy. In addition, vegans and vegetarians had the lowest inflammatory biomarkers, while omnivores had the highest. Based on the results, the scientists concluded that the consumption of predominantly animal products is reflected in the microbial profile, which can lead to inflammatory processes and metabolic disorders such as obesity, insulin resistance and cardiovascular disease.

Thus, a diet low in plant fibers promotes the growth of pathogenic bacterial flora and increases the risk of increased intestinal permeability, the risk of mitochondrial disorders, as well as disorders of the immune system and the development of the inflammatory process.  

Main conclusions:   

• add prebiotics to your diet. According to WHO recommendations, the norm of prebiotic fiber is 25-35 g / day.
• limit the amount of animal products to 10% of the daily calorie intake.
• if you are not yet a vegetarian, then before cooking, remove excess fat from meat, remove skin from poultry; remove the fat that forms during cooking. 

Microbiome and weight

There are two largest groups of bacteria – Firmicutes and Bacteroidetes, which account for up to 90% of all bacteria in the intestinal microflora. The ratio of these groups is a marker of predisposition to excess weight. Firmicutes are better at extracting calories from food than Bacteroidetes, controlling the expression of genes responsible for metabolism, creating a scenario in which the body stores calories, which leads to weight gain. The bacteria of the Bacteroidetes group are specialized in the breakdown of plant fibers and starch, while the Firmicutes prefer animal products. It is interesting that the population of African countries, unlike the Western world, is in principle not familiar with the problem of obesity or overweight. One well-known study by Harvard scientists published in 2010 looked at the effect of the diet of children from rural Africa on the composition of the intestinal microflora. Scientists have determined that the microflora of the representatives of Western society is dominated by Firmicutes, while the microflora of the inhabitants of African countries is dominated by Bacteroidetes. This healthy ratio of bacteria in Africans is determined by a diet that consists of foods rich in plant fiber, no added sugar, no trans fats, and no or minimal representation of animal products. In the study above, this hypothesis was confirmed once again: Vegans have the best ratio of Bacteroidetes / Firmicutes bacteria to maintain optimal weight. 

Main conclusions: 

• While there is no ideal ratio that equates to excellent health, it is known that a higher abundance of Firmicutes relative to Bacteroidetes in the gut microflora is directly associated with higher levels of inflammation and greater obesity.
• Adding vegetable fibers to the diet and limiting the proportion of animal products contributes to a change in the ratio of different groups of bacteria in the intestinal microflora.

Microbiome and eating behavior

The role of the gut microflora in regulating eating behavior has previously been underestimated. The feeling of satiety and satisfaction from food is determined not only by its quantity and calorie content!

It has been established that SCFAs formed during the fermentation of plant prebiotic fibers by bacteria activate the production of a peptide that suppresses appetite. Thus, a sufficient amount of prebiotics will saturate both you and your microbiome. It has recently been found that E. coli secretes substances that affect the production of hormones that suppress the activity of the digestive system and the feeling of hunger. E. coli does not threaten life and health if it is within the normal range. For optimal representation of E. coli, fatty acids produced by other bacteria are also necessary. Main conclusions:

• A diet rich in prebiotic fiber improves the hormonal regulation of hunger and satiety. 

Microbiome and anti-inflammatory effect

As scientists note, the bacterial microflora increases the availability for absorption of various polyphenols – a special group of anti-inflammatory and antioxidant substances contained in plant foods. Unlike healthy dietary fibers, toxic, carcinogenic or atherogenic compounds are formed from the amino acids that occur during the breakdown of food proteins of animal origin under the influence of the colon microflora. However, their negative impact is mitigated by a sufficient intake of dietary fiber and resistant starch, which is present in potatoes, rice, oatmeal and other plant foods. According to Alexey Moskalev, Russian biologist, doctor of biological sciences, professor of the Russian Academy of Sciences, this is due to the fact that fibers increase the rate of passage of food residues through the large intestine, switch the activity of microflora to themselves, and contribute to the predominance of the proportion of microflora species that digest carbohydrates over species that break down mainly proteins . As a result, the probability of damage to the DNA of intestinal wall cells, their tumor degeneration and inflammatory processes is reduced. Red meat proteins are more prone to decomposition with the formation of harmful sulfides, ammonia and carcinogenic compounds than fish proteins. Milk proteins also provide a large amount of ammonia. Conversely, vegetable proteins, which legumes are rich in, in particular, increase the number of beneficial bifidobacteria and lactobacilli, thereby stimulating the formation of such important SCFAs. Main conclusions:

• It is useful to limit animal products in the diet. For example, for 1-2 days a week exclude all animal products from the diet. Use vegetable sources of protein. 

Microbiome and Antioxidants

To protect against free radicals, some plants produce flavonoids, a class of plant polyphenols that are important antioxidants in the human diet. The beneficial effect of antioxidants on reducing the risk of cardiovascular disease, osteoporosis, cancer and diabetes, as well as the prevention of neurodegenerative conditions has been studied. Numerous studies have shown that adding polyphenols to the diet leads to a significant reduction in markers of oxidative stress.

Polyphenols have been shown to increase the number of bifidus and lactobacilli in the intestinal microflora, while reducing the number of potentially harmful Clostridial bacteria. Main conclusions:

• the addition of natural sources of polyphenols – fruits, vegetables, coffee, tea and cocoa – contributes to the formation of a healthier microbot. 

Author’s Choice

A vegetarian diet is beneficial in reducing the risk of a wide range of diseases and maintaining active longevity. The above studies confirm that a significant role in this belongs to the microflora, the composition of which is formed by our choice of food. Eating a predominantly plant-based diet containing prebiotic fiber can help increase the abundance of beneficial microflora species that help reduce excess body weight, prevent chronic diseases and slow down aging. To learn more about the world of bacteria, join the First Conference in Russia, which will be held September 24-30. At the conference, you will meet with more than 30 experts from all over the world – doctors, nutritionists, geneticists who will talk about the incredible role of small bacteria in maintaining health!