Did you ever wonder if the food you eat has a direct effect on your health, well-being – and longevity? Well, I’m here to end that mystery. You ARE the foods you eat. Welcome to the Nutrition Facts podcast – I’m your host, Dr. Michael Greger.
Today, we look at the best way to control Diabetes – starting with the remarkable results of a crossover study randomizing hundreds of people with diabetes to one and a third cup of millet every day.
How does millet come to the help of diabetics? A substantial portion of the starch in millet is resistant starch––meaning resistant to digestion in our small intestine, so, providing a bounty for the good bugs in our colon––all way more than more common grains like rice or wheat, but proso and kodo millet lead the pack.
What’s going on? The protein matrix in millet not only acts as a physical barrier, but actually also partially sequesters your starch-munching enzyme, and the millet polyphenols also can act as starch blockers in and of themselves.
Millet also has markedly slower stomach-emptying times than other starchy foods. If you eat white rice, boiled potatoes, or pasta, your stomach takes about an hour to digest it before starting to slowly dump it into your intestines, and two or three hours to empty about halfway. Whereas, you eat sorghum or millet, and stomach emptying doesn’t even start until two or three hours, and may take five hours to empty even halfway. Note this was for both a thick millet porridge and for just millet couscous. Since the non-viscous millet couscous meal was also equally slow in emptying, this suggests that there may just be something about millet itself that helps slow stomach emptying, which should blunt the blood sugar spike. But you don’t know, until you put it to the test.
And indeed, millet caused about a 20 percent lower surge in blood sugar than the same amount of carbs in the form of rice. Remember how excited I was to show you how it only took the body like half the insulin to handle sorghum, compared to a grain like corn? Well, millet did even better.
Give a group of prediabetics only about three-quarters of a cup of millet a day, and within six weeks, their insulin resistance dropped so much their prediabetic fasting blood sugars turned into non-prediabetic blood sugars. This so-called “self-controlled” clinical trial, the same subjects before and after, is just a sneaky way of saying an uncontrolled trial. There was no control group that didn’t add the millet or added something else. And we know just being in a study under scrutiny can cause people to eat better in other ways. So, we don’t know what role, if any, the millet itself played. What we need is a randomized, controlled crossover trial where the same people eat both a millet-containing and non-millet containing diet and see which works better.
And, here we go! A randomized, crossover study having hundreds of patients both do an American Diabetes Association-type diet, with and without about one and one-third cup of millet every day, and…the millet-based diet lowered hemoglobin A1C levels––meaning an improvement in long-term blood sugar control, along with some side benefits, like lowering cholesterol.
The target for good blood sugar control recommended by the American Diabetes Association is an A1C less than 7. They started out at 8.37, but after a few months on millet, dropped it to an average of 6.77. Is it just because they lost weight or something? No, suggesting that it was an effect specific to the millet. But they didn’t just give millet. They mixed the millet with split black lentils and spices, and we know from dozens of randomized, controlled experimental trials in people with and without diabetes that the consumption of pulses (meaning beans, split peas, chickpeas, or lentils) can improve long-term measures of blood sugar control, like A1C levels. So, while the researchers conclude that millets have the potential for a protective role in the management of diabetes, a more accurate conclusion might be a mix of millet and lentils can be protective––though, hey, maybe the spices helped too. They didn’t say which ones they used, and I couldn’t get a hold of the authors, but a similar study done by one of the same researchers included about a tablespoon a day of a mixture of fenugreek, coriander, cumin, and black pepper, with a fifth spice, perhaps cinnamon or turmeric.
In our next story – we look at the reason why professional diabetes associations recommend bean, chickpea, split pea, and lentil consumption as a means of optimizing diabetes control.
How did doctors treat diabetes before insulin? Almost a thousand medicinal plants [were] described as antidiabetic agents,…most of [which] have been used in traditional medicine.” And, these included beans. Of course, just because something has been used for centuries doesn’t mean it’s safe. Other treatments for diabetes have included arsenic and uranium. Thankfully, many of these remedies fell by the wayside, but “[s]cientific interest in the antidiabetic potential of bean[s] never vanished completely, and even was raised in the past decade.”
“Health authorities from all over the world universally recommend increasing [the] consumption of whole grains and legumes for health promoting diets.” And, one of the reasons is that they may decrease insulin resistance—the defining trait of type 2 diabetes.
“Diabetes…[is] a global public health…epidemic. Although [oral hypoglycemic medications] and injected insulin are the mainstay…treatment[s] of diabetes and are effective in controlling [high blood sugars], they have prominent side effects and fail to significantly alter the course of diabetic complications.” [C]ommon side effects [include] weight gain, [swelling],…liver disease.”
But, I want to emphasize that second part. “[T]he mainstay [of diabetic] treatment fail[s] to significantly alter the course of diabetic complications.” Shouldn’t that be the whole point of treatment? Thankfully, “lifestyle modifications have proven to be greatly effective in the management of this disease.” And, if there is one thing diabetics should eat, it’s legumes: beans, chickpeas, split peas, and lentils.
The European Association for the Study of Diabetes, the Canadian Diabetes Association, and the American Diabetes Association all “recommend the consumption of dietary pulses as a means of optimising diabetes control.” What are pulses? They’re peas and beans that come dried, so a subset of legumes, so excluding green beans and fresh green peas, which are considered more like vegetables, and also excluding the so-called oilseeds—soybeans and peanuts.
This review compiled 41 “randomised controlled experimental trials,” including more than a thousand patients, corroborating the official “diabetes association nutrition guidelines recommending the consumption of pulses as a means of optimising diabetes control.” Any better than any of the others? Well, some of the strongest evidence came from the studies that used chickpeas, and in terms of beans, pintos and black beans may beat out kidney beans. Compared to the blood sugar spike of straight white rice, black beans and rice, and pinto beans and rice appeared to beat out kidney beans and rice. This may be because “dark red kidney [beans] [can] have lower levels of indigestible starch.” One of the reasons beans are so healthy is they contain compounds that partially block our starch-digesting enzyme, which allows some starch to make it down to our colon to feed our good gut bacteria.
And, in fact, the inhibition of this starch-eating enzyme, amylase, just by eating beans, approximates that of a carb-blocking drug, acarbose, sold as Precose, “a popular diabetes medication.” The long-term use of beans may normalize hemoglobin A1C levels (which is how you track diabetes) “almost as well as” the drug, without drug side effects, with names like “acute generalized exanthematous pustulosis.”
Finally today, we look at the best diet for diabetes prevention.
There are all sorts of different scoring systems to rate diet quality. My favorite, for its simplicity, is the “dietary phytochemical index”: a fancy name for a simple concept. It’s just the percentage of your calories from whole plant foods, so, 0 to 100. The average American diet has a score of 12. Twelve out of a hundred; so, like on a scale of one to ten, our diet is a one.
You can split people up based on how they score, and show how the higher you score, the better your metabolic markers when it comes to diabetes risk. There appears to be like this stepwise drop in insulin resistance and insulin-producing beta-cell dysfunction as you eat more and more plant-based. And that highest group was only scoring about 30—less than a third of their diet was whole plant foods, but better than the lowest, which was down around the standard American diet.
No wonder diets centered around plants, emphasizing legumes—beans, split peas, chickpeas, and lentils—whole grains, vegetables, fruits, nuts, and seeds, and discouraging “most or all animal products…are especially potent in preventing type 2 diabetes,” and as a little bonus, “have been associated with much lower rates of obesity, hypertension, hyperlipidemia, cardiovascular mortality, and cancer.” And not just preventing type 2 diabetes, but treating it as well. A systematic review and meta-analysis found that the “[c]onsumption of vegetarian diets is associated with improved [blood sugar] control.” But, how much improved?
Here’s one of the latest trials. The effect of a strictly plant-based diet centered around brown rice—it was done in Asia—versus the conventional diabetic diet on blood sugar control of patients with type 2 diabetes: a 12-week randomized clinical trial. For the diabetic control diet, they set up food exchanges, and calculated specific calorie and portion controls, whereas on the plant-based diet, people could eat much as they want—that’s one of the benefits. The emphasis is on food quality rather than quantity, and they still actually lost more weight. But, even after controlling for the greater abdominal fat loss in the plant-based group, they still won out. Of course, it only works if you actually do it, but those that pretty much stuck to the healthier diet dropped their A1c levels 0.9 percent, which is what you get taking the leading diabetes drug—but, of course, only with good side effects.
Yeah, but would it work in an underserved population? The impact of a plant-based diet support program on mitigating type 2 diabetes in San Bernardino, the poorest city of its size in California. A randomized controlled trial, but not of a plant-based diet itself as the title suggests, but of just an education program telling people about the benefits of a plant-based diet for diabetes. And then, it was up to them, and… still got a significant improvement in blood sugar control. Here are the numbers. Got a little better in the control group, but way better in the plant-based instruction and support group.
And, more plant-based diets are not just effective in the prevention and management of diabetes, but also its complications. Check this out. One of the most devastating complications of diabetes is kidney failure. This shows the decline in kidney function in eight diabetics in the one or two years before switching their diets. They all showed this steady, inexorable decline on a fast track, to complete kidney failure and dialysis. But then… they switched to a special supplemented vegan diet, and their kidney decline was stopped in its tracks. Imagine if they had switched a year or two earlier!
Most diabetics don’t actually end up on dialysis, though, because they die first. “Cardiovascular disease is the major cause of premature mortality” among diabetics; that’s why plant-based diets are perfect. “There is a general [scientific] consensus that the elements of a whole food plant-based diet—legumes, whole grains, fruits, vegetables, and nuts, with limited or no intake of [processed] foods and animal products—are highly beneficial for preventing and treating type 2 diabetes. Equally important, plant-based diets address the bigger picture…by simultaneously treating cardiovascular disease [our #1 killer]” along with obesity, high blood pressure, lowering inflammation. And, we can throw cancer in the mix too—our #2 killer. The bottom line is that “the case for using a plant-based diet to reduce the burden of diabetes and improve overall health has never been stronger.”
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