Why does switching from white rice to brown rice enable overweight individuals to significantly reduce their weight, their waist size, their blood pressure, and the level of inflammation within their bodies?
We think it might be the fiber. Brown rice has four times as much dietary fiber as white rice, including prebiotic types of fiber that foster the growth of our good bacteria, which may help account for the anti-obesity effects of brown rice.
Besides the prebiotic fiber, when brown rice is milled into white, there are all sorts of vitamins and minerals that also are lost, as well as phytonutrients such as gamma oryzanol, which may help shift one’s preferences to healthier foods. Petri dish studies suggest gamma oryzanol may help lower cholesterol. And, along with other compounds found in the rice bran, which is what makes brown rice brown, gamma oryzanol may inhibit human cancer cell growth through antioxidant means, anti‑proliferative and pro-cancer cell suicide mechanisms, immune system modulation, and increasing barrier protection. However, this was all seen in test tubes, not people.
There are two human studies, though. The Adventist Health Study found that brown rice was one of four foods associated with significantly decreased risk of colorectal polyps, which can turn into colorectal cancer. Eating cooked green vegetables every day was associated with 24 percent lower risk, which was as much as eating dried fruit just three times a week. Eating beans, chickpeas, split peas, or lentils at least three times a week was associated with 33 percent lower risk, but brown rice seemed to garner 40 percent lower risk, and that was just a single serving or more a week.
The other human study reported increased muscle strength after supplementation with a brown rice compound in hopes that it could provide a side effect-free alternative to anabolic steroids. The dose the researchers were giving, however, is equivalent to approximately 17 cups of brown rice a day, so it’s not clear if it works at practical doses.
Naturally pigmented rice, such as black rice and red rice, may be even more nutritious than brown rice. During the last decade, research has shown that these natural anthocyanin plant pigments may have a variety of beneficial effects. Anthocyanins are what make blueberries blue and red cabbage red. “Recent recognition of the fact that taking diet rich in plant foods lowers the risks of cancer promotes the enthusiasms in isolating…[these components as] pharmaceutical agents”—but why not just eat the blueberries or add some red cabbage to your stir fry atop some colorful rice?
Black, purple, and red rice—and their pigment compounds—have been found to be involved in a variety of antioxidant, anti-cancer, anti-heart disease, anti-diabetes, and anti-allergy activities, but these were all studies done in a lab. We don’t yet have clinical studies, but these pigmented rice varieties have everything that brown rice has, plus five times more antioxidants and a variety of extra benefits. That’s why I, or rather my rice cooker, has always cooked red, black, or purple rice with a handful of lentils or split peas thrown in for good measure, since they cook in the same time frame.
But why don’t most people even choose brown over white? Well, brown rice does not last as long on the shelves, so it can actually be more expensive even though it’s less processed. White rice, on the other hand, is like food for the apocalypse, even putting Twinkies to shame. White rice was still edible after 30 years—though, by then, it may have a “slight playdough” odor.
Michael Greger, M.D.