The statement has been tossed around that people have more bacterial DNA than human DNA. However you slice it, whether by bacteria cells (38 trillion) versus human cells (30 trillion) (2) or bacteria genes (30 million) versus human genes (23,000) (1), the results points toward the human body as an ecosystem of gut microbes, like a “coral reef”.

This idea is dubbed by famous microbiologist Frederick Bushman in a February 26 2023 issue of El Pais (2). Or as microbiologist Ignacio López-Goñi puts it, “We are superorganisms in which 1% of our genome is inherited from our parents and 99% from our microbes (1).”

Researchers and health experts are convinced that inside the human “coral reef“ are causes of so many of today’s health problems, and source of so many of today’s solutions.

While most strains of gut microbes are helpful and healthy, others have been identified as harmful. A recent study by researchers at Yale University found that Morganella morganii and Escherichia coli produce molecules that are toxic to human DNA, also causing tumors in a mice study. Another common bacterium in the stomach, Helicobacter pylori, is associated with an increased risk of gastric cancer (3).

On the other hand, “The common factor…in almost all diseases is the loss of diversity [in the microbiota], which is possibly also related to protein- and fat-rich diets [that include] few vegetables. The microbiota that we had in the colon to digest those vegetables is lost and disappears,” according to gastroenterologist Francisco Guarner, a member of the International Human Microbiome Consortium’s scientific committee who is quoted in the January 2 2023 issue of El Pais (1).

The National Institute of Health’s PubMed reported that over multiple generations, a low-fiber, low-MAC (Microbiota accessible carbohydrates) diet results in a progressive loss of diversity, which is not recoverable upon the reintroduction of dietary MACs. MACs found in dietary fiber, play a key role in shaping this microbial ecosystem, and are strikingly reduced in the Western diet relative to more traditional diets (5).

Kayo Kurotani of the National Institutes of Biomedical Innovation in Tokyo, found that high fiber Natto is made from soybeans fermented with Bacillus subtilis, and miso is soybeans fermented with Aspergillus oryzae. His study of 93,000 Japanese and their eating habits showed that men who ate the most natto were 24% less likely than those who rarely ate, and women were a 21% lower risk of dying from cardiovascular causes (3).

1) https://english.elpais.com/science-tech/2023-01-03/we-are-half-human-half-bacteria-what-the-microbes-in-our-bodies-can-do-for-us.html

2) https://english.elpais.com/science-tech/2023-02-26/study-reveals-exchange-of-microbiome-bacteria-could-increase-risk-of-disease.html?outputType=amp

3) https://www.reuters.com/article/us-health-diet-soy/miso-soup-might-be-one-comfort-food-that-helps-you-live-longer-idUSKBN2012J6

4) https://english.elpais.com/science-tech/2022-10-31/gut-dwelling-bacterium-singled-out-as-the-possible-cause-of-colorectal-cancer.html

5) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4850918/

Other related articles: https://www.cnbc.com/2023/03/02/nutritionist-from-japan-shares-foods-she-eats-every-day-to-stay-healthy-young-and-live-longer.html