Eating the Way Nature Intended

The Paleolithic period, also known as the Stone Age, only goes back about two million years. Humans and other great apes have been evolving for the last 20 million years, starting back in the Miocene era. We hear a lot about the paleolithic diet, but that only represents the last 10 percent of hominoid evolution. What about the first 90 percent?

During the Miocene era, the diet “is generally agreed to have been a high-fiber plant-based diet…” For the vast majority of our family’s evolution, we ate what the rest of our great ape cousins eat—leaves, stems, and shoots (in other words, vegetables), as well as fruits, seeds, and nuts. I explore this in my video Lose Two Pounds in One Sitting: Taking the Mioscenic Route.

“Anatomically, the digestive tracts of humans and great apes are very similar.” In fact, our DNA is very similar. So, what do our fellow great apes eat? Largely vegetarian diets with high greens and fruit consumption. Just largely vegetarian? It’s true that chimpanzees have been known to hunt, kill, and eat prey, but chimpanzees’ “intake of food of animal origin is still at a very low level…with only 1.7% of chimpanzee feces providing evidence of animal food consumption.” This is based on eight years of work collecting nearly 2,000 fecal samples. So, even the most carnivorous of great apes appears to eat about a 98 percent plant-based diet. In fact, we may be closest to the diet of bonobos, one of the less known great apes, who eat nearly exclusively plant-based diets, as well.

Even our Paleolithic hunter-gatherer ancestors must have done an awful lot of gathering to get the upwards of 100 grams of fiber a day they may have consumed. What would happen if researchers put people on an actual Paleolithic diet? Not a supermarket-checkout-aisle-magazine paleo diet or some caveman blogger diet, but an actual 100-grams-of-daily-fiber diet or, even better, a mioscenic diet, taking into account the last 20 million years of evolution since we split with our common great ape ancestors.

Dr. David Jenkins and colleagues gave it a try and “tested the effects of feeding a diet very high in fiber.” How high? We’re talking 150 grams of daily fiber, far higher than the recommended 20 to 30 grams a day. However, 150 grams is similar to what populations in rural Africa used to eat—populations almost entirely free from many of our chronic killer diseases, such as colon cancer and heart disease.

The high-fiber diet didn’t mess around. Lunch, for example, could include Brussels sprouts, okra, green peas, mushrooms, filberts, and a plum. And dinner? How about asparagus, broccoli, eggplant, carrots, and honeydew melon? Surely, simply eating a lot of fruits, veggies, and nuts can’t be very satisfying, right? Actually, it got the maximum satiety rating from every one of the ten subjects, unlike the starch-based and low-fat diets which scored lower. Why? “All of the diets were designed to be weight-maintaining,” meaning the researchers didn’t want weight loss to confound the data. So, to get a full day’s calories of whole plant foods, the subjects had to eat about 11 pounds of food a day! Not surprisingly, this resulted in some of the largest bowel movements ever recorded in the medical literature, with men on the high-fiber vegetable-based diet exceeding a kilogram of fecal weight per day. You know how some people on weight loss diets lose two pounds a week? Well, in this study, the subjects dropped two pounds in one sitting.

That wasn’t the only record-breaking drop: A 33 percent drop in LDL cholesterol within just two weeks was seen. Even without any weight loss, bad cholesterol levels dropped by one-third within two weeks. That’s one of the biggest drops I’ve ever seen in any dietary intervention—better than achieved on a starch-based vegetarian diet or  a low saturated fat American Heart Association-type vegetarian diet. This was a “cholesterol reduction equivalent to a therapeutic dose of a statin” drug. So, we need to take a drug to get our cholesterol levels down to where they would be normally were we to eat a more natural diet.

We’ve been eating 100 grams of fiber every day for millions of years. This diet is similar to what’s eaten by populations who don’t suffer from many of our chronic diseases. Maybe this shouldn’t be called a “very high fiber” diet. Maybe what we eat today should be considered a very low, extremely fiber-deficient diet.

Maybe it’s normal to eat 100 grams of fiber a day. Maybe it’s normal to be free of heart disease. Maybe it’s normal to be free of constipation, hemorrhoids, diverticulitis, appendicitis, colon cancer, obesity, type 2 diabetes, and all other the diseases of Western civilization.


How do we know our ancient ancestors ate more than 100 grams of fiber a day? We can examine their fossilized fecal matter, as I discuss in my video Paleopoo: What We Can Learn from Fossilized Feces.

For more evidence on what our natural diet is, see my What’s the Natural Human Diet? video.

Other popular paleo videos include:

Excited to share what you’ve learned about diet? Well, it turns out you can share more than my videos. Check out How to Become a Fecal Transplant Super Donor.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Follow the 5-to-1 Rule for Packaged Foods

When people think fiber, they think constipation. And it’s true: If we could get Americans to eat just the minimum recommended daily intake of fiber-containing foods, we could save our country $80 billion—and that’s just from the effects on constipation alone. But that’s not all. “Accumulating evidence indicates that greater dietary fiber intakes reduce risk for type 2 diabetes, cardiovascular disease, certain cancers, weight gain, obesity, and diverticular disease, as well as functional constipation.” So, we need to eat more fiber-rich foods, which means eating more whole grains, vegetables, fruits, and legumes (beans, split peas, chickpeas, and lentils).

As fiber intake goes up, the risk of metabolic syndrome appears to go down, with less inflammation and an apparent step-wise drop in obesity risk. It’s therefore no surprise that greater dietary fiber intake is associated with a lower risk of heart disease: There is a 9 percent lower risk for every additional 7 grams a day of total fiber consumed, which is just some rice and beans or a few servings of fruits and veggies.

How does fiber do its magic? What are the mechanisms by which dietary fiber may extend our lifespan? It helps get rid of excess bile, feeds our good bacteria, and changes our gut hormones, which collectively helps control our cholesterol, body weight, blood sugar, and blood pressure, thereby reducing the risk for cardiovascular disease. Reducing inflammation is a whole other mechanism by which fiber may help prevent chronic disease.

An accompanying editorial to a fiber and heart disease meta-analysis implored doctors to “enthusiastically and skil[l]fully recommend that patients consume more dietary fibre”––which means a lot of whole plant foods. If we do buy something packaged, however, the first word in the ingredients list should be “whole.” But, even if it is, the rest of the ingredients could be junk. A second strategy is to look at the ratio of grams of carbohydrates to grams of dietary fiber. We’re looking for about 5 to 1 or less. For example, whole-wheat Wonder Bread passes the first test: The first word in its ingredients list is “whole.” However, it then includes corn syrup and the contents of a chemistry set. So, let’s see if it passes the 5-to-1 rule.

In my video The 5-to-1 Fiber Rule. I show examples of some Nutrition Facts labels. The whole-wheat Wonder Bread lists 20 grams of carbs and 2.7 grams of dietary fiber per serving. Dividing the carbohydrates by the dietary fiber, 20 divided by 2.7, is about 7, which is obviously more than 5, so back it goes onto the shelf. It’s better than white Wonder Bread, though, which comes in at over 18. Ezekiel sprouted grain bread, however, makes the cut: 15 divided by 3 equals 5.

You can do the same thing with breakfast cereal. Multi-Grain Cheerios sounds healthy but has a ratio over 7. Uncle Sam original cereal is an example of one that makes the cut, sliding in under 4.

The editorial concluded that the “recommendation to consume diets with adequate amounts of dietary fibre may turn out to be the most important nutritional recommendation of all.”


I love producing videos about practical, day-to-day decision-making. Next time you go to the grocery store, look for products that fit the 5-to-1 ratio rule. They aren’t easy to find!

Eating fiber-rich foods is more than just a way to avoid constipation. For example, watch my videos Fiber vs. Breast Cancer and How to Prevent a Stroke.

There’s a misconception that we can’t digest fiber. We can’t do it alone, but we can with a little help from our gut flora friends. See Prebiotics: Tending Our Inner Garden and Gut Microbiome: Strike It Rich with Whole Grains.

This isn’t to downplay all the suffering caused by constipation. Check out How Many Bowel Movements Should You Have Every Day? and Should You Sit, Squat, or Lean During a Bowel Movement? to learn more.

Isn’t this talk of fiber reductionist? Good question! So good, in fact, that I created an entire video about it. See Is the Fiber Theory Wrong?.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Bad Gut Flora Can Undermine Our Natural Liver Detox

Colon cancer is a leading cancer killer, yet there’s a paradox in Africa: Africans rarely get the disease, even in modern times when they are no longer eating their traditional whole food diet—that is, when they are no longer eating lots of fiber, fresh fruits, and vegetables. It is likely their continued low prevalence of colon cancer—50 times lower than ours—is related to their low intake of animal protein and fat, which I explored in my Solving a Colon Cancer Mystery video. But why would animal protein and fat increase cancer risk? Well, as I noted in my video Bowel Wars, if you eat egg whites, for example, about 5 to 35% of the protein isn’t digested and absorbed. Instead, it ends up in the colon, where it undergoes a process called putrefaction.

When animal protein putrefies in the gut, it can lead to the production of the rotten egg gas, hydrogen sulfide, which, in addition to its objectionable odor, can produce changes that increase cancer risk. Putrefying protein also produces ammonia.

Over a lifetime on a standard Western diet, the bacteria in our colon may release the amount of ammonia found in 1,000 gallons of Windex. At concentrations found day-to-day inside the colon on usual Western diets, ammonia destroys cells, alters DNA synthesis, increases cellular proliferation, may increase virus infections, and favor the growth of cancerous cells. The products of protein and fat digestion are to blame. We can double ammonia concentrations in the colon by eating a lot of meat.

However, if you put people on a plant-based diet, the enzyme activity that creates the ammonia in the colon drops like a rock within just one week.

Other bacterial enzymes are affected as well. For example, vegetables in the broccoli family can boost detoxifying enzymes in the liver. (See Prolonged Liver Function Enhancement from Broccoli for more on this.) These so-called phase 2 enzymes, UDP-glucuronosyltransferases, detoxify drugs and chemicals by applying a chemical straightjacket. They can deactivate the date rape drug GHB or take the carcinogens in meat, like benzopyrene, and render them harmless before dumping them back into the intestine for disposal. But if our liver detoxifies it, why is benzopyrene in meat still associated with rectal cancer? Certain bacteria in our gut contain the opposite enzyme—that removes the straightjacket and frees the carcinogen to wreak a last bit of havoc before it leaves the body.

Within one week of eating plant-based, researchers found we can drop that enzyme activity in our colon by about 30%. But, this was with a raw, “extreme” vegan diet. What about a regular vegetarian diet? Compared to a pound-of-meat-a-day diet, those placed on a meat-free diet for one month experienced a 70% drop in “toxifying” activity. And long-time vegetarians exhibit just a fraction of carcinogen-releasing activity compared to those on a standard American diet.

So, might this help explain the increased risk of colorectal cancer in the United States? Researchers put it to the test by taking biopsies from the lining of the colons of Americans versus Africans to measure cell proliferation rates, a marker for increased cancer risk and decreased cancer survival. As you can see in my Putrefying Protein and “Toxifying” Enzymes video, the researchers found proliferating cells throughout the colons of Caucasian-Americans and African-Americans, but only a few were seen in the African biopsies. The Africans had dramatically lower proliferation rates.

Overall, higher colorectal cancer risk was associated with “higher dietary intakes of animal products and higher colonic populations of potentially toxic hydrogen and secondary bile-salt-producing bacteria.”

And, while the researchers were getting the biopsies, they looked around a little: They detected only 4 problems out of the 18 African colons they looked at. Out of the 17 African-American and 17 Caucasian-American colons, however, they found 21 problems in each group, including polyps, diverticulosis, and lots of hemorrhoids. “The remarkably pristine condition of the colons in our African volunteers further supports our impression that [African] colons were, in general, far healthier than those of age-matched Americans.”

I encourage you to check out my Stool pH and Colon Cancer, How to Treat Kidney Stones with Diet, and Testing Your Diet with Pee & Purple Cabbage videos, which explain how we should strive to have an acidic environment in our colon (but alkaline in our kidneys).

For more on bowel health, see

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: