The types of bacteria that compose the intestinal flora and their proportions vary from individual to individual. Because of this, as a rule, each person has a unique intestinal flora. On the other hand, although unique to each individual, people from the same country, for example, are known to have similar intestinal flora compared to people from other countries when their living environment and conditions, such as climate and diet, are similar. Focusing on the fact that there are certain similarities among these intestinal flora, attempts to classify them according to the recent patterns (types) that make up the intestinal flora have been made mainly in the United States and Europe. In 2011, Arumugam et al. reported that human intestinal flora can be divided into three types. In this instance, three classified intestinal flora types are named “enterotypes”.Enterotype 1 is a group of intestinal bacteria with a high occupancy of the genus Bacteroides, enterotype 2 is a group with a high occupancy of the genus Prevotella, and enterotype 3 is a group with a high occupancy of the genus Ruminococcus, which are now called B-type, P-type and R-type after the initial letters of the bacterial genus that characterizes each type. Afterwards, Holmes et al. proposed the enterotype, which further divides type B into two types, B1 and B2, based on the occupancy rate of the genus Faecalibacterium (type B1 has a higher occupancy rate of the genus Faecalibacterium than type B2), and for the intestinal flora of Japanese people, they further divided it into five types of groups with a significantly high occupancy rate of the genus Bifidobacterium.

Anyway, it may be safe to say that the first three types are the enterotypes that are commonly seen worldwide across racial groups. Later clinical studies have revealed the characteristics of susceptibility to disease by enterotype.

Enterotype I: This type is characterized by high levels of Bacteroides bacteria and tends to be more common in ethnic groups with high animal protein and fat intake, such as Europeans, Americans, and Chinese. Some recent reports indicate that about 80% of Japanese people are of this type. Bacteroides are so-called “thin bacteria” that help prevent obesity. Bacteroides bacteria decompose dietary fiber and produce butyric acid, which improves metabolism by reducing fat incorporation into fat cells and stimulating fat burning in the muscles. Therefore, this type is said to tend to have fewer myocardial infarctions and cerebral infarctions. Enterotype II: This type is characterized by a large number of bacteria of the genus Prevotella. This bacterium has the ability to break down indigestible dietary fiber (resistant starch, non-digestible dextrin), and is said to be common among peoples with grain-based diets, such as those in South America, Southeast Asia, and Africa. Prevotella bacteria differentiate dietary fiber to produce the short-chain fatty acids acetic acid and propionic acid. This type is considered the healthiest because it reduces the rise in blood glucose levels and is less likely to cause diabetes. Enterotype III: This type is characterized by a large number of bacteria of the genus Ruminococcus. This type is common among ethnic groups with omnivorous tendencies and is comparatively common among Japanese. It is said to break down cellulose in dietary fiber, further increasing absorption of carbohydrates and fats, and making people more susceptible to obesity, myocardial infarction, and cerebral infarction.

As described above, the classification of intestinal flora into enterotypes has been found to be associated with lifestyle-related diseases. In our clinic, we are particularly committed to the prevention of lifestyle-related diseases from the viewpoint of enterotype, and we are working to prevent the onset of such diseases through intestinal activities for patients with obesity and fatty liver, which are said to be the beginning of the metabolic domino effect.

It has been reported that among obese individuals, the number of bacteria in the phylum Firmicutes is increased, while the number of bacteria in the phylum Bacteroides is decreased. Bacteria of the phylum Firmicutes break down indigestible dietary fiber to produce energy sources such as short-chain fatty acids. It is possible that an increase in the number of bacteria in the phylum Firmicutes may contribute to the development of obesity by increasing energy absorption efficiency. For example, it has actually been reported that a decrease in the proportion of the opportunistic bacterium Bacteroides tetaiotaomicron and a relative increase in the bacteria of the phylum Firmicutes can lead to obesity and diabetes. Tetaiotaomicron bacteria break down dietary fiber into short-chain fatty acids, which helps to reduce fat storage and blood sugar increases. That is, it is suggested that disruption of the intestinal microflora (called dysbiosis), represented by a decrease (simplification) of intestinal bacterial species, an abnormal increase in bacterial species that should be scarce, or a decrease in bacterial species that should be dominant, may decrease the number of species that produce short-chain fatty acids, resulting in a change in the host’s energy absorption efficiency, and may even promote fat accumulation by partially acting on the feeding center, thereby causing obesity.

Dullness, sagging, wrinkles, and blotches on the skin are also very much related to lifestyle-related diseases. Skin aging is related not only to oxidative stress (UV rays) but also to glycation stress. Particularly in obesity and diabetes, AGEs (Advanced Glycation End products: AGEs) are produced by the combination of excess sugar and proteins. This is called the “Glycation reaction (Maillard reaction). Lactic acid and short-chain fatty acids produced by butyric acid bacteria, bifidobacteria, and lactic acid bacteria suppress this Maillard reaction and act to reduce glycation stress. Furthermore, the age-related decrease in short-chain fatty acid-producing bacteria causes an increase in glycation stress. Glycation stress causes AGEs to be deposited in tissues and binds to RAGE (Receptor for AGEs) to generate inflammatory cytokines, which in turn induce tissue damage due to micro-inflammation, promoting skin aging. This glycation stress also results from excess triglycerides and LDL cholesterol (LDL-C), which can also cause dyslipidemia. Furthermore, lifestyle habits such as lack of sleep, overwork, excessive exercise, prolonged full-body tanning, and excessive alcohol consumption can lower the immune system and cause skin to age more rapidly, so these conditions should be avoided. Other known diseases resulting from glycation stress-induced alterations of proteins in the body include cataracts, age-related macular degeneration, osteoporosis, osteoarthritis (OA), Alzheimer’s disease, decreased ovarian function, aging hair, and atherosclerosis.

In this way, for the prevention and early detection of disease, it is necessary to first learn the status of the patient’s intestinal bacteria, and then determine the balance of the approximately 400 types of intestinal bacteria in order to determine the treatment.  In our clinic, we suggest various biotics based on the results of intestinal flora analysis.