You may have heard the expression “knowledge is power.” Well – today – we’re going to give you more power to control your diet and lifestyle – by giving you the facts. Welcome to the Nutrition Facts podcast. I’m your host – Dr. Michael Greger.
Today on the show, we discover how whole (ideally intact!) grains—ancient and modern alike–should be an integral part of everyone’s diet. And we start out with ancient grains. Sounds mysterious –right?
The number one killer in the United States and around the world is what we eat, killing millions more than tobacco, for example. What are the five most important things we can do to improve our diets, based on the single most comprehensive global study of the health impact of nutrition? Eat less salt, eat more nuts, eat more non-starchy vegetables, eat more fruit, and, finally, eat more whole grains.
Any particular type of whole grains? What about so-called ancient grains? Are they any better than modern varieties? Like what about kamut, the so-called mummy wheat, supposedly unearthed from an Egyptian tomb?
After World War II, the wheat industry selected particularly high-yielding varieties for pasta and bread. Over the past few years, though, some of the more ancient varieties have been reintroduced on the market, defined basically as those that haven’t been changed over the agricultural revolutions of the last century.
Nutritionally, einkorn wheat—the oldest wheat—and kamut have more of the eyesight-improving yellow carotenoid pigments, like lutein and zeaxanthin, compared to modern bread and pastry wheat because the pigments have been bred out of bread intentionally. People want their white bread white, but modern pasta flour (durum wheat) maintains much of that yellow hue nutrition.
Yes, modern wheat may have less lutein, but, for example, tends to have more vitamin E, based on straight vitamin and mineral concentrations, it’s pretty much a wash. They both have lots of each, but the primitive wheats do have more antioxidant capacity––likely due to their greater polyphenol content. But to know if this makes any difference, you have to put it to the test.
If you expose human liver cells to digested bread made out of ancient grains—kamut and spelt (heritage wheat)—or modern strains, and then expose the cells to an inflammatory stimulus, the modern wheat strains seem less able to suppress the inflammation. The investigators conclude that despite the fact that these different grains seem to be very similar nutritionally, they seemed to exert different effects on human cells, “confirming the potential health benefits of ancient grains.” But this was in a petri dish. What about in people?
If ancient wheats are better at suppressing inflammation, what if you took people with irritable bowel syndrome and randomized them to receive six weeks of wheat products make out of ancient wheat—kamut, in this case—or modern wheat? Same amount of wheat, just different types. If there’s no difference between the wheats, there’d be no difference in people’s symptoms, right? But, here’s how the control groups did on the modern wheat. Switched to the kamut, they experienced less abdominal pain, less frequent pain, less bloating, more satisfaction with stool consistency, and less interference with their quality of life. So, after switching to the ancient wheat, patients experienced a significant global improvement in the extent and severity of symptoms related to their irritable bowel.
What about liver inflammation? The liver function of those with nonalcoholic fatty liver disease randomized to eat kamut improved, compared to those eating the same amount of regular wheat, suggesting kamut is superior. In diabetics, better cholesterol and insulin sensitivity on the same ancient grain. In those with heart disease, better blood sugar control and better cholesterol. Better artery function in those without overt heart disease.
The bottom line is findings derived from human studies suggest that ancient wheat products are more anti-inflammatory and improve things like blood sugar control and cholesterol. Given that the overall number of human interventional trials is still small, it is not possible to definitively conclude that ancient wheat varieties are superior to all commercial, modern wheat counterparts in reducing chronic disease risk, but the best available data does suggest they’re better if you have the choice.
Regardless of what type of wheat you may eat, word to the wise: don’t eat the plastic bread-bag clip. A 45-year-old guy presents with bloody stools, and later questioned, the patient admitted to habitually eating quickly without chewing properly.
So, what can we eat to increase good gut bacteria richness in our colon? Let’s find out.
Yes, we live in a so-called obesogenic environment—cheap junk food everywhere, thanks in part to subsidies going to the “’food industrial complex’ which manufactures obesogenic foods that foster addiction.” The root causes may make obesity difficult to escape. But look, a lot of people do. If it was just the external environment, why isn’t everyone obese?
Some individuals seem to be more susceptible than others. This suggests a genetic component, supported by studies of twins and adopted kids. But, the genes we’ve identified only account for maybe 6 to 11 percent of the variation in body mass index between individuals. So, maybe variation in our “other genome” may be playing a role—all the different microbes that inhabit our body. We have a hundred times more bacterial genes inside us than human genes.
What this study found is that people tend to fall into one of two groups: those who have lots of different types of bacteria in their gut (so-called high gut “bacterial richness”), and those with relatively few types. And those with low bacterial richness had more overall body fat, insulin resistance (the cause of type 2 diabetes), high triglycerides, and higher levels of inflammatory markers, like C-reactive protein, compared to high bacterial richness individuals. And not only did folks with lower bacterial richness start out heavier, but the obese individuals with lower bacterial richness also gained more weight over time.
The question then becomes: can a dietary intervention have any impact? They tried a calorie-restricted diet, which by definition isn’t very sustainable. But what we can do is increase our fruit and vegetable intake, which is associated with high bacterial richness. One of “[a] number of studies [that] have associated increased microbial richness, with diets higher in fruits, vegetables, and fiber.”
Now, just giving fiber-type supplements didn’t seem to boost richness. But the compositional complexity of a whole food—like whole grains—could potentially support a wider scope of bacterial types, thereby leading to an increase in diversity. But human studies to investigate the effects of whole grains have been neglected— until now.
Folks were given whole grain barley, brown rice, or both, for a month. And they did cause an increase in bacterial community diversity. Therefore, it may take a broad range of substrates to increase bacterial diversity, and this can be achieved by eating whole plant foods.
And the alterations of gut bacteria in the study coincided with a drop in systemic inflammation in the body. See, we used to think that the way fiber in whole grains helped us is by gelling in our small intestines right off our stomach, slowing the rate at which sugars were absorbed, blunting the spike in blood sugars one might get from refined carbs. But now we know the fiber is broken down in our colon by our friendly flora, which release all sorts of beneficial substances into our bloodstream that can have anti-inflammatory effects, as well. So, maybe what’s happening in our large intestine helps explain the protective effects of whole grain foods against type 2 diabetes.
And interestingly, the combination of both barley and brown rice worked better than either alone—suggesting a synergistic effect. This may help explain “the discrepancy of the health effects of whole grains obtained in [population-based versus] interventional studies.”
Observational studies strongly suggest that those who consume three servings of whole grains a day tend to have a lower body mass index, less belly fat, less tendency to gain weight. But, recent clinical trials, where you, like, randomize people to eat white bread rolls, versus whole wheat rolls, failed to provide evidence of a beneficial effect on body weight.
Of course, whole grains are so superior nutritionally that they should continue to be encouraged. But, maybe the “interventional trials…failed to show [weight] benefits because they focused on a limited selection of whole grains, while in [the population studies], subjects are [more] likely to consume a diverse set of whole grains which might have synergistic activities.”
Finally, today, the remarkable impact of the structure of food beyond nutritional content or composition.
“Food structure,” not just nutrient composition, may be “critical for optimal health.” It should come as no surprise that cornflakes and Rice Krispies cause a much greater spike in blood sugars than rice or corn-on-the-cob; but it’s not just the added sugar. “Even with identical [ingredients], food structure can make a major difference…” For example, if you compare the absorption of fat from peanuts, compared to the exact same number of peanuts ground into peanut butter, you flush more than twice the amount of fat down the toilet when you eat the peanuts themselves, since no matter how well you chew, small bits of peanuts trap some of that oil makes it down to your colon. And, “the physical form of food” not only alters fat absorption, but carbohydrate absorption as well. For example, rolled oats have a significantly lower glycemic index than instant oatmeal, which is just oats, but in thinner flakes. And oat flakes cause lower blood sugar and insulin spikes than powdered oats. Same single ingredient: oats, but in different forms can have different effects.
Why do we care? Well, the overly “rapid absorption” of carbohydrates after eating a high-glycemic index meal can trigger “a sequence of hormonal and metabolic changes” that may promote excessive eating. They took a dozen obese teen boys and fed them different meals, each with the same number of calories, and just followed them for the next five hours to measure their subsequent food intake. And those that got the instant oatmeal went on to eat 53 percent more than after eating the same number of calories of steel-cut oatmeal. The instant oatmeal group was snacking within an hour after the meal, and goes on to accumulate significantly more calories throughout the rest of the day. Same food, but different form, different effects.
Instant oatmeal isn’t as bad as some breakfast cereals, though, which can get up into the 80s or 90s—even a cereal with zero sugar like shredded wheat. The “new [industrial] methods” used to create breakfast cereals, such as extrusion cooking and explosive puffing, accelerate starch digestion and absorption, causing an exaggerated blood sugar response, added sugar or not. Shredded Wheat has the same ingredients as spaghetti—just wheat—but has twice the glycemic index.
When you eat spaghetti, you get a gentle rise in blood sugars. If you eat the exact same ingredients made into bread form, though, all the little bubbles in bread allow your body to break it down quicker; so, you get a big spike in blood sugars, which causes our body to overreact with an exaggerated insulin spike. And that actually ends up driving our blood sugars below fasting levels, and that can trigger hunger. Experimentally, if you infuse someone with insulin so their blood sugars dip, you can cause their hunger to spike, and, in particular, hunger cravings for high-calorie foods. In short, lower-glycemic index foods may “help one to feel fuller longer than equivalent [higher-glycemic index] foods.”
Researchers randomized individuals into one of three breakfast conditions: oatmeal made from quick oats, the same number of calories of Frosted Flakes, or just plain water, and then measured how much people ate for lunch three hours later. Not only did those who ate the oatmeal feel significantly fuller and less hungry…they indeed then went on to eat significantly less lunch. Overweight participants ate less than half as many calories at lunch after eating the oatmeal for breakfast—hundreds and hundreds of calories less. The breakfast cereal was so unsatiating that the Corn Flakes group ate as much as the breakfast-skipping, water-only group. It’s as if the cereal group hadn’t eaten breakfast at all!
Feed people Honey Nut Cheerios, and hours later they feel significantly less full, less satisfied, and more hungry than those fed the same number of calories of oatmeal. Though both breakfasts were oat-based, the higher glycemic index, reduced intact starch, and reduced intact fiber in the Cheerios seemed to have all conspired to diminish appetite control. “The trial was funded by the Pepsi Corporation,” makers of the Quaker oatmeal, pitted against the Cheerios from rival General Mills. And an exposé on industry-funded study manipulation later revealed that the study originally included another arm, Quaker Oatmeal Squares. “I am sorry that the Oat Squares did not perform as well as hoped,” the researcher told Pepsi, which “decided to publish only the results about its oatmeal.”
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