Most people think all you need for a healthy gut is to consume bacterial-fortified yogurt products. In reality, the balance of bacteria in your gut may hold a key toward managing systemic inflammation in our bodies.
First of all, there are a lot of bacteria in our guts. The human body contains about 100 trillion cells, but the number of bacteria in the gut is 10 times greater in number. Furthermore, these bacteria are not just taking up space; they are actually providing numerous useful functions that make them a symbiotic “organ” to our own body. In particular, they can ferment carbohydrates to provide additional energy, make various vitamins, break down toxins we might ingest, and help prevent the growth of pathogenic bacteria.
Although there are literally millions of different bacteria in the world, only about 500 species actually reside in our guts. We also know that these gut bacteria can be further divided into three distinct bacterial ecosystems (1). Just like there are four unique blood groups that can classify every human, we also have three distinct bacterial systems. Once one of these systems becomes established in the gut, it begins to alter the gut environment that only certain species of other bacteria can follow and safely begin their symbiotic relationship with us.
So how does each ecosystem of bacteria keep out the bad apples (like Salmonella)? First of all, the bacteria in each distinct ecosystem have to alert our own immune cells in the intestine that they are friends, not foes. Apparently they have learned how to suppress the immune system in our own cells so they can co-exist in our gut (2). However, I believe even though these ecosystems of bacteria can be recognized as friends and not foes, they still need unique nutrients to help them act as the first line of defense against millions of other harmful bacteria.
Those nutrients are polyphenols. In the plant world, these polyphenols act as antibiotics against microbial attack. There is evidence that the “good” bacteria in our gut can use them as a means to help ward off invading bacteria that threaten our own unique bacterial fingerprint. Of course, the only way we can continue to help our unique bacterial partners in our gut is to continue to eat lots of fruits and vegetables that are rich in polyphenols. That’s why your grandmother told you to eat an apple a day to keep the doctor away.
- Arumugam M, Raes J, Pelletier E, et al. “Enterotypes of the human gut microbiome.” Nature DOI: 10.1038/nature09944 (2011).
- Round JL, Lee SM, Li Jennifer, Tran G, Bana J, Chatila TA and Mazmanian SK. “The toll-like receptor 2 pathway establishes colonization by a commensal of the human microbiota.” Science DOI:10.1126/scienc.1206095 (2011).
- Moreno S, Scheyer T, Romano CS, and Vojnov AA. “Antioxidant and antimicrobial activities of rosemary extracts linked to their polyphenol composition.” Free Radic Res 40: 223-231 (2006).