The key to a healthy gut

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.


  1. Arumugam M, Raes J, Pelletier E, et al. “Enterotypes of the human gut microbiome.” Nature DOI: 10.1038/nature09944 (2011)
  2. 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)
  3. 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)

Nothing contained in this blog is intended to be instructional for medial diagnosis or treatment. If you have a medical concern or issue, please consult your personal physician immediately.

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This entry was posted in Zone Health and tagged , , , by Dr. Barry Sears. Bookmark the permalink.

About Dr. Barry Sears

Dr. Barry Sears is a leading authority on the impact of the diet on hormonal response, genetic expression, and inflammation. A former research scientist at the Boston University School of Medicine and the Massachusetts Institute of Technology, Dr. Sears has dedicated his research efforts over the past 30 years to the study of lipids. He has published more than 30 scientific articles and holds 13 U.S. patents in the areas of intravenous drug delivery systems and hormonal regulation for the treatment of cardiovascular disease. He has also written 13 books, including the New York Times #1 best-seller "The Zone". These books have sold more than 5 million copies in the U.S. and have been translated into 22 different languages.

10 thoughts on “The key to a healthy gut

  1. Dr Sears, can you tell us the amount of polyphenols in a serving (1/2 C) of red wine? I cannot find any data – also, does coffee have significant polyphenols or not? I have conflicting data on that.

  2. What a change from about 30 years ago when they where saying that all the wonderful colorful grapes, etc. where bad for us. They were actually saying that the colors somehow had a chemical that caused cancer! Talk about a 180 degree turn and thank goodness. Same for eggs, animal fats, and who knows what else from ancient man’s diet will soon be vindicated. I hate politically correct eating and science that is still wet behind the ears. It would appear that if your grandmother used a half teaspoon of cod liver oil a few times a week, and warned about eating too much bread and sugar (saving sugar treats for rare events), and she made her own wine for a nip now and then, and she lived to 100 you would pretty much have the perfect example of how to live to be 100.

  3. Should I take a polyphenal supplement? I’ve also been doing the paleo diet and i’m 48 years old was just wondering where u get ur calcium from with out the dairy. They say women need more as they get older. what is ur take on that?

      • My omega 3 s contain 1407 mg of fish oil, 900 mg of omega 3 fatty acids (600 EPA and 300 mg DHA). My grape seed extract is 350 mg. I am currently taking 2 omegas and 1 grape seed capsule. My calculations state that I should take 1 more omega as well to match what you say is sufficient. Is this correct? (I am 42 years old)

    • If you are eating 10 servings of fruits and vegetables per day, then you probably don’t need an polyphenol supplements. On the other hand, if you start adding more omega-3 fatty acids (and it is estimated on a true paleo diet that is at least six grams per day) you will need extra polyphenols to protect the fatty acids from oxidation. Magnesium is more important than calcium for bone health, but the largest factor in osteoporosis is increased cellular inflammation. That’s why the extra omega-3 fatty acids are important.

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