#117: Jeff Leach- Human Food Project Reveals Results of Gut Bacteria on A Paleo Diet

by Mike Mutzel


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About Jeff Leach

Jeff Leach is the Founder of the Human Food Project. author of Honor Thy Symbionts and Rewild. His opinions on health and nutrition have appeared as Op-ed articles in the New York Times, San Francisco Chronicle, Sydney Morning Herald and his peer-reviewed research has been published in the British Journal of Nutrition, European Journal of Clinical Nutrition, BioScience and Microflora, Journal of Archaeological Science, Public Health Nutrition and many others. He lives in New Orleans – but hopes to spend more time in Africa.

The Paleo diet is all the rage right now. But ditching grains and eating more meat is a PG-13 version of the true Paleo diet. Internationally recognized microbiome researcher Jeff Leach, came on the podcast to discuss what a “primal diet” really is. This is graphic, but telling… While studying gut bacteria of primal, hunter gatherers (the Hadza tribe in Tanzania) Jeff began to see why the Hadza have twice as many microbes as we (industrialized humans) do. And, incidentally, the Hadza suffer from zero of the chronic ailments that plague many North Americans and Europeans. He witnessed the Hadza hunt and kill an Impala (deer), then eat the stomach, intestines and colon of sushi style while field dressing the animal. No hand sanitizing soap was used prior to kissing and touching their children, or spouses back in the village. But don’t worry, you need not start hunting and killing the neighborhood deer–Jeff shared many practical tips that can help you restore the health of you gut bacteria, and body, in a civilized manner. #decisions #begoodtoyourbody #instagood #instafood #primalfood #primaleats #liver #beefliver #paleodiet #paleoapproved #paleorecipes #organs #organmeat #wholeanimal #cleaneating #eatarainbow #eatpaleo #paleo #progress #paleofriendly #paleolovers #primal #cavemanfood #cleaneats #grassfed #functionalmedicine #guthealth #highintensityhealth #paleofriendly

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Related Books and Products

Honor Thy Symbionts


An Epidemic of Absence: A New Way of Understanding Allergies and Autoimmune Diseases

Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues

Contact Jeff

Get Involved with the American Gut Project

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Show Notes

1:29 Jeff’s Involvement with Gut Bacteria: Jeff has a background in anthropology. About 10 years ago, when his very young daughter was diagnosed as a type-1 diabetic, he embarked upon a quest to figure out why. He learned of the impact of gut bugs and nutrition. He began attending microbiology conferences. He has now had a great number of papers published and eventually ended up in Africa.

2:36 Bacterial Diversity: About 5 years ago gut studies were being done with animals or western humans. Every human’s gut was already compromised, in a state of dysbiosis. He began studying African hunter-gatherers called the Hadza. A small group of them still practice their traditional lifestyle. He lived with them and collected data. The results of this collaboration with researchers from around the country will be published shortly.

4:50 Early Results of Hadza Study: The Hadza live outside, where the babies are still born in the dirt, where food is hunted and gathered. They have very different and more diverse gut microbes and skin microbes than us.

5:44 Microbial Transfer: Jeff wrote a book called Honor thy Symbionts, and most recently wrote the book, Rewild, where he discusses his work in Africa. One of the most stunning things he learned working with the Hadza, was the intimate relationship the hunters had with the animals. The blood of an animal is on everyone working to field dress it. They eat some of it raw on the spot. Microbes from skin, feces, blood, bowel, and elsewhere on the animal are transferred to the hunter. Jeff saw them remove the feces from an animal’s colon and eat the colon raw. Researchers sampled the microbes on the skin of the hunters, before, during and after the butchering process. When the hunters would return home, they would rejoin their families, transferring microbes to them through touch. The microbial transfer also applies to the women who dig in the soil for roots and bring home those microbes and share with their families.

7:49 Microbial Diversity: The Hadza have nearly twice as many types of bacteria in their guts as we have. Research is indicating that a drop in diversity may impact some disease states. We disconnect from the microbial world by spending about 90% of our time in the home, the office, or our cars. The Hadza spend 100% of their time outside. In addition, we scrub the microbes from our food supply.

9:13 How Can We Increase Our Microbial Diversity? Humans evolved with our innate and adaptive immunity outside with animals. We have cut off that exposure, added antibiotic exposure and chlorinated water and we see a drop in microbial diversity. Is there a way to rekindle our microbiome diversity? People are trying to capture that variability and put it in a pill. There are some simple things we can do to help our microbial diversity. Get outside. Do some gardening. Buy lightly rinsed vegetables from your local farmer’s market. Handle animals. Don’t be afraid of dirt. Open the windows in your home and car.

12:30 The American Gut Project: Jeff co-founded a project called American Gut. You donate $99 to the project. They send you a poop kit and a detailed questionnaire. You take a sample, fill out the questionnaire and send it in. In a few months you get a printout to say who is in your poop. So far, they have raised over a million dollars to do the sampling. They have sent out more than 15,000 kits. Over 5,000 of those that have been returned have been analyzed. It’s the world’s largest open source. All of the data is available to any researcher in the world. All personal information is scrubbed before it is uploaded.

14:31 Patterns and Trends in Project Results: The American Gut Project isn’t perfect science, because so much is self-reported and people lie. Jeff says that there are extraordinary patterns. Across all age groups, individuals who reported eating more than 25 to 30 species of plants per week, had much more diverse microbiome than people who ate fewer plant species per week. The average American eats less than 5 and those are predominantly potatoes, tomatoes, iceberg lettuce, etc.

15:39 Increasing Microbiome Diversity: Increasing diversity and quantity of plants you consume, is an easy way to increase the diversity of the bacteria in your body. All plants contain dietary fiber. Our bodies do not break it down, so it passes to the colon where our bacteria break it down and turn it into energy.

16:42 Diversity is Protective: In any ecological setting, the more diverse and robust the species are in the ecosystem, the more resilient it is. Your body is your own personal ecosystem. Increasing diversity potentially reduces susceptibility to disease.

18:19 Comparing the Hadza Microbiome to Westerners: Jeff recommends the book Missing Microbes by Martin Blaser, MD. Hazda warriors have about 1500 varieties of microbes and we have about 800. Some may be there, but below detectible levels. It has not been determined if our lost microbes are contributing to disease. Jeff found that just living near the Hadza in Tanzania increased his microbial diversity. When he ate, drank and lived with the Hadza, he gained even more microbial species. He wonders whether they were new bacteria or a kick start of something he had in small amounts.

20:47 Fecal Transplant with a Hunter Gatherer: Yes, Jeff did a fecal transplant with a healthy Hadza warrior. Knowing exactly what was in the Hadza’s feces and what was in Jeff’s, what would change? How long would the change stay once he resumed his western diet and western life? When he returns to Africa and lives as a hunter gatherer again, will the transferred and by now undetectable bacterial species return? The results will be published soon. He doesn’t recommend fecal transplants with hunter gatherers this for us.

22:33 Paleo, Vegans, Vegetarians, and Dietary Fiber: The American Gut Project found that the average of people who identify themselves as subscribing to a version of a Paleo diet eat less than about 20 grams of dietary fiber per day. That is less than the amount recommended by the USDA. Vegans, in the study, ate the most dietary fiber and vegetarians ate the second greatest amount. If you really want to eat Paleo, Jeff says, increase the amount of plants in your diet to an ancestral level of fiber.

24:18 The Acidic Versus the Alkaline Gut: It was discovered that Hadza children, as young as 2 and 3 years old, eat 50, 100 to 200 grams of fiber in a day in the form of roots, tubers, and fruit. Their stomachs are distended, fermenting the fiber. This makes the colon more acidic. Bacteria are very ph. sensitive. Perhaps we have created a problem with our far more alkaline western gut. Research is beginning to show that as your colon becomes more acidic, the gut leaks less. Young Hadza children ate more dietary fiber than adults, the opposite of U.S. dietary recommendations.

30:44 Are Poop Pills in Your Future? Every five years the government puts out new dietary recommendations. Of the experts putting together the current plan, there is no microbiologist. We are mostly microbes. Our microbes have more DNA in our bodies than we do, yet our nation’s dietary recommendations to not take this into account. Jeff believes that one day our produce sections in our grocery stores will have charts and labeling regarding dietary fiber for your microbes.

34:25 “It’s the Fiber, Stupid”: We know that bacteria eat fiber. Increasing diversity and quantity of fiber in your diet will improve your bacterial profile. It also has the bonus of improving metabolic issues. Monday morning you should get out a note pad and record every species of plant you eat in that week. If you are not eating 25 to 30, you need to step it up.

36:03 Preparing for a Newborn’s Microbiome: Do your research on the microbiome. Avoid an unnecessary C-section and breastfeed. Jeff’s daughter did not have the benefit of these and she was exposed to broad spectrum antibiotics. He believes that they are major contributors in her becoming type 1 diabetic.

39:33 Testing Your pH: pH. test strips for urine testing are found at your local pharmacy, but you can use them to test your stool. Wipe your butt after defecating and stick the test strip in the feces on the toilet paper. Turn the strip upside down and it will change color as the moisture flows downward.  The acidity and alkalinity levels will respond to your diet. .

41:09 Is Meat Bad for Us? Studies that show that meat is bad for us are generally done in the absence of dietary fiber. Jeff finds that adding dietary fiber to his diet when it is heavily laden with fat and meat protein, totally changes his bacterial profile.

42:00 Human Food Bar: People want food to nurture their microbiome. Jeff and some friends created The Human Food bar, at It is somewhat similar to a Clif Bar, but it contains far more dietary fiber, 9 grams of dietary fiber and 6 grams of prebiotic agave fiber. You should focus on diversity and fiber from vegetables and fruit. The Human Food Bar is more of a trail snack and a means of education.

44:39 Cannabis and Your Gut: Jeff has done some experimentation and found a shift in his microbiome, but there is no way to tell if it is a shift for the better or the worse.

46:04 Intestinal Worms: Intestinal worms used to be common, but we have wiped them out. Jeff highly recommends the exceptional book, An Epidemic of Absence: A New Way of Understanding Allergies and Autoimmune Diseasesby Moises Velasquez-Manoff.

47:39 Jeff’s Morning Routine: He is usually up between 4 and 6 in the morning. The first thing he does is check his Google alerts on the microbiome. He usually does some writing in the morning. When in West Texas, he is building adobes on his property or he goes hiking. His highest morning priority is to feed his gut microbes. Leeks and onions are two foods he does not ever want to do without. He chops the entire leek, hard leaves and all. He puts it in a pan with some bacon, bacon fat, a chopped onion and 2 scrambled eggs. Leeks and onions contain special prebiotic fibers and other valuable polysaccharides.

50:00 Another Way Our Diets have changed: Most of the fiber we eat is quickly digested and absorbed. We eat highly soluble fiber. Your ancestors ate the entire plant. Your grandmother called it Roughage. We tend to eat the broccoli tops, but not the fibrous valuable stem. Don’t focus on soluble or insoluble. Toughen up and ate the whole plant. That is what your ancestors did.

53:53 Jeff’s Parting Advice: Your health is within your own grasp. You don’t need to drug your microbiome into compliance. We ate our way into this problem and we can probably eat our way out. Just taking on a few ecological principles of managing your own microbiome will pay dividends for you and your family for a lifetime.


Join the conversation

  1. Excellent podcast! I love them all but I really liked this one. I’m learning so much about gut microbes and how to increase my diversity. Thanks for all of the podcasts!

    • Thanks for the note, Amy! I’ll pass it on to Jeff.

      I really enjoyed this session with him as well. It was so down to earth and practical.

      P.S. I would be honored for a brief review in iTunes about something you learned in this episode (or others) when you get a free moment 🙂



  2. Excellent episode, packed with important information!

    Your podcast is definitely one of a kind. I really like that you put so much focus on the microbiome, toxic mold, and other similar topics.

    Suggestion: You should try to get Dr. Art Ayers on as a guest ( He has a lot of knowedlege to share and is my go-to guy for high-quality info about the microbiome.

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