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Boosting Gut Flora without Probiotics

Obesity is so rare among those eating plant-based diets (see my video Thousands of Vegans Studied), nutrition researchers have been desperate to uncover their secret. Yes, they tend to eat fewer calories, but not that many fewer. In the past I’ve made videos about a couple of the theories that have emerged. Maybe because people eating plant-strong diets express more of the fat shoveling enzyme inside the power plants—the mitochondria–within our cells (How to Upregulate Metabolism). Maybe it’s because they grow different populations of good bacteria in their gut (Gut Flora & Obesity). Maybe it’s because they’re avoiding the endocrine disrupting industrial pollutants in the meat supply. An Obesity-Causing Chicken Virus may even be contributing. We’re still not sure, but the theories keep coming.

Maybe it’s the propionate, an anti-obesity compound made by our gut bacteria when we feed them fiber. Watch my 2-min. video Fawning Over Flora for details.

Our friendly flora’s digestion of fiber also yields another short chain fatty acid called butyrate, which appears to protect against colon cancer. Butyrate may also explain why fiber-filled plant-based diets are so anti-inflammatory. A recent review concluded that “butyrate seems to exert broad anti-inflammatory activities and might be [a] good candidate to evaluate in the fight against obesity-associated and systemic inflammation in general.” See my coverage of that review in my 1-min. video Boosting Good Bacteria in the Colon Without Probiotics.

Since butyrate is a byproduct of fiber digestion, we can boost its production by eating more plant foods, and we can boost the number of butyrate-producing bacteria in our colon by really eating more plant foods–those eating vegetarian harbor more butyrate-producing bacteria.

For more on fabulous fiber, see What Women Should Eat to Live Longer and Relieving Yourself of Excess Estrogen. For a sampling of my other videos on keeping your colon happy, see Kiwifruit For Irritable Bowel SyndromeFlax and Fecal Flora, and Bristol Stool Scale.

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

15 responses to “Boosting Gut Flora without Probiotics

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    1. Probiotics can be beneficial when taking antibiotics and after stopping them as they help balance the intestinal flora. Different strains of probiotics do different things but it appears that the 2 most important strains are lactobacillus acidophilus and L. bulgaricus. (S. S. Biradar, S. T. Bahagvati, Baburao Shegunshi, Probiotics And Antibiotics: A Brief Overview, The Internet Journal of Nutrition and Wellness ISSN: 1937-8297 2005). To colonize the intestinal area with probiotics, it is recommended to take more than 5 billion colony forming units (CFU) daily 2 to 4 hours after the antibiotic dose and from 1 to 3 weeks after finishing antibiotic treatment. Probiotics should be taken with or immediately after food as the food dilutes out the acid and raises the pH thereby helping the good bacteria survive its transit to the intestinal tract. (Expert Rev Anti Infect Ther. 2012;10(4):407-409)

    2. My understanding is that probiotics cannot take hold in the gut until the overgrowth of “bad” flora is under control. Until that point, probiotics may merely control symptoms without addressing the root of the problem.

      I am nearly finished with a 16-week cleanse for my own intestinal dysbiosis and I have so far achieved favorable results. If you’re interested in hearing more, please feel free to contact me! I am merely a satisfied customer of the creator of the cleanse and am in no other way affiliated.

  1. I don’t understand how “good” bacteria are growing better than “bad” bacteria in a high fiber colon environment. If I look at humans in general – if there are enough natural resources – the “bad” humans tend to take and destroy it all. How are bacteria different ?

  2. Md’s should stay in their field of studies. In an in depth medical degree, the subject of nutrition is negligible compared to the vast amount of information that is available on the subject. Also an MD should not go out of his field of studies in treating ailments because he can be disbarred from his practice. That being said, Dr. Greger should either cease his preaching on this subject or seek an alternative degree as a Naturopathic Physician or a Dietician and only then will his opinion on nutrition hold merit. Good Day.


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