A Grain That's Good for Your Cardiovascular System
Diets that contain buckwheat have been linked to lowered risk of developing high cholesterol and high blood pressure. The Yi people of China consume a diet high in buckwheat (100 grams per day, about 3.5 ounces). When researchers tested blood lipids of 805 Yi Chinese, they found that buckwheat intake was associated with lower total serum cholesterol, lower low-density lipoprotein cholesterol (LDL-the form linked to cardiovascular disease), and a high ratio of HDL (health-promoting cholesterol) to total cholesterol.
Buckwheat's beneficial effects are due in part to its rich supply of flavonoids, particularly rutin. Flavonoids are phytonutrients that protect against disease by extending the action of vitamin C and acting as antioxidants. Buckwheat's lipid-lowering activity is largely due to rutin and other flavonoid compounds. These compounds help maintain blood flow, keep platelets from clotting excessively (platelets are compounds in blood that, when triggered, clump together, thus preventing excessive blood loss, and protect LDL from free radical oxidation into potentially harmful cholesterol oxides. All these actions help to protect against heart disease.
Buckwheat also contains almost 86 milligrams of magnesium in a one-cup serving. Magnesium relaxes blood vessels, improving blood flow and nutrient delivery while lowering blood pressure-the perfect combination for a healthy cardiovascular system.
Better Blood Sugar Control and A Lowered Risk of Diabetes
The nutrients in buckwheat may contribute to blood sugar control. In a test that compared the effect on blood sugar of whole buckwheat groats to bread made from refined wheat flour, buckwheat groats significantly lowered blood glucose and insulin responses. Whole buckwheats also scored highest on their ability to satisfy hunger.
When researchers followed almost 36,000 women in Iowa during a six-year long study of the effects of whole grains and the incidence of diabetes, they found that women who consumed an average of 3 servings of whole grains daily had a 21 percent lower risk of diabetes compared to those who ate one serving per week. Because buckwheat is a good source of magnesium, it is also important to note that women who ate the most foods high in magnesium had a 24 percent lower risk of diabetes compared to women who ate the least.
Canadian researchers, publishing their findings in the Journal of Agricultural and Food Chemistry have found new evidence that buckwheat may be helpful in the management of diabetes. In a placebo-controlled study, a single dose of buckwheat seed extract lowered blood glucose levels by 12-19% at 90 and 120 minutes after administration when fed to laboratory animals with chemically-induced diabetes. No glucose reduction was seen in animals given placebo. The component in buckwheat responsible for its blood glucose-lowering effects appears to be chiro-inositol, a compound that has been shown in other animal and human studies to play a significant role in glucose metabolism and cell signaling. While researchers do not yet know precisely how it works, preliminary evidence suggests chiro-inositol makes cells more sensitive to insulin and may even act as an insulin mimic. Results of the Canadian study were so promising that one of the lead investigators, Roman Przbylski, is currently collaborating with Canadian-based Kade Research to develop new buckwheat varieties with much higher amounts of chiro-inositol. Although the animals used in this study had the equivalent of Type 1 diabetes in humans, the researchers are confident that buckwheat will exert similar glucose-lowering effects when given to animals with Type 2 diabetes, which is the next study on their agenda. Type 2 or non-insulin dependent diabetes, which is by far the most common form in humans (90% of diabetes in humans is Type 2), is characterized by an inability of cells to respond properly to insulin.
Buckwheat and other whole grains are also a rich source of magnesium, a mineral that acts as a co-factor for more than 300 enzymes, including enzymes involved in the body's use of glucose and insulin secretion.
The FDA permits foods that contain at least 51% whole grains by weight (and are also low in fat, saturated fat, and cholesterol) to display a health claim stating consumption is linked to lower risk of heart disease and certain cancers. Now, research suggests regular consumption of whole grains also reduces risk of type 2 diabetes. (van Dam RM, Hu FB, Diabetes Care).
In this 8-year trial, involving 41,186 particpants of the Black Women's Health Study, research data confirmed inverse associations between magnesium, calcium and major food sources in relation to type 2 diabetes that had already been reported in predominantly white populations.
Risk of type 2 diabetes was 31% lower in black women who frequently ate whole grains compared to those eating the least of these magnesium-rich foods. When the women's dietary intake of magnesium intake was considered by itself, a beneficial, but lesser- 19%- reduction in risk of type 2 diabetes was found, indicating that whole grains offer special benefits in promoting healthy blood sugar control. Daily consumption of low-fat dairy foods was also helpful, lowering risk of type 2 diabetes by 13%. Get the benefits of both buckwheat and dairy by enjoying a hearty breakfast of hot buckwheat topped with low-fat milk and a spoonful of maple syrup.
Helps Prevent Gallstones
Eating foods high in insoluble fiber, such as buckwheat, can help women avoid gallstones, shows a study published in the American Journal of Gastroenterology.
Studying the overall fiber intake and types of fiber consumed over a 16 year period by over 69,000 women in the Nurses Health Study, researchers found that those consuming the most fiber overall (both soluble and insoluble) had a 13% lower risk of developing gallstones compared to women consuming the fewest fiber-rich foods.
Those eating the most foods rich in insoluble fiber gained even more protection against gallstones: a 17% lower risk compared to women eating the least. And the protection was dose-related; a 5-gram increase in insoluble fiber intake dropped risk dropped 10%.
How do foods rich in insoluble fiber help prevent gallstones? Researchers think insoluble fiber not only speeds intestinal transit time (how quickly food moves through the intestines), but reduces the secretion of bile acids (excessive amounts contribute to gallstone formation), increases insulin sensitivity and lowers triglycerides (blood fats). Abundant in all whole grains, insoluble fiber is also found in nuts and the edible skin of fruits and vegetables including tomatoes, cucumbers, many squash, apples, berries, and pears. In addition, beans provide insoluble as well as soluble fiber.
Health-Promoting Potential Equal to or Even Higher than that of Vegetables and Fruits
Research reported at the American Institute for Cancer Research (AICR) International Conference on Food, Nutrition and Cancer, by Rui Hai Liu, M.D., Ph.D., and his colleagues at Cornell University shows that whole grains, such as buckwheat, contain many powerful phytonutrients whose activity has gone unrecognized because research methods have overlooked them.
Despite the fact that for years researchers have been measuring the antioxidant power of a wide array of phytonutrients, they have typically measured only the "free" forms of these substances, which dissolve quickly and are immediately absorbed into the bloodstream. They have not looked at the "bound" forms, which are attached to the walls of plant cells and must be released by intestinal bacteria during digestion before they can be absorbed.
Phenolics, powerful antioxidants that work in multiple ways to prevent disease, are one major class of phytonutrients that have been widely studied. Included in this broad category are such compounds as quercetin, curcumin, ellagic acid, catechins, and many others that appear frequently in the health news.
When Dr. Liu and his colleagues measured the relative amounts of phenolics, and whether they were present in bound or free form, in common fruits and vegetables like apples, red grapes, broccoli and spinach, they found that phenolics in the "free" form averaged 76% of the total number of phenolics in these foods. In whole grains, however, "free" phenolics accounted for less than 1% of the total, while the remaining 99% were in "bound" form.
In his presentation, Dr. Liu explained that because researchers have examined whole grains with the same process used to measure antioxidants in vegetables and fruits-looking for their content of "free" phenolics"-the amount and activity of antioxidants in whole grains has been vastly underestimated.
Despite the differences in fruits', vegetables' and whole grains' content of "free" and "bound" phenolics, the total antioxidant activity in all three types of whole foods is similar, according to Dr. Liu's research. His team measured the antioxidant activity of various foods, assigning each a rating based on a formula (micromoles of vitamin C equivalent per gram). Broccoli and spinach measured 80 and 81, respectively; apple and banana measured 98 and 65; and of the whole grains tested, corn measured 181, whole wheat 77, oats 75, and brown rice 56.
Dr. Liu's findings may help explain why studies have shown that populations eating diets high in fiber-rich whole grains consistently have lower risk for colon cancer, yet short-term clinical trials that have focused on fiber alone in lowering colon cancer risk, often to the point of giving subjects isolated fiber supplements, yield inconsistent results. The explanation is most likely that these studies have not taken into account the interactive effects of all the nutrients in whole grains-not just their fiber, but also their many phytonutrients. As far as whole grains are concerned, Dr. Liu believes that the key to their powerful cancer-fighting potential is precisely their wholeness. A grain of whole wheat consists of three parts-its endosperm (starch), bran and germ. When wheat-or any whole grain-is refined, its bran and germ are removed. Although these two parts make up only 15-17% of the grain's weight, they contain 83% of its phenolics. Dr. Liu says his recent findings on the antioxidant content of whole grains reinforce the message that a variety of foods should be eaten good health. "Different plant foods have different phytochemicals," he said. "These substances go to different organs, tissues and cells, where they perform different functions. What your body needs to ward off disease is this synergistic effect - this teamwork - that is produced by eating a wide variety of plant foods, including whole grains."
Lignans Protect against Heart Disease
One type of phytonutrient especially abundant in whole grains such as buckwheat are plant lignans, which are converted by friendly flora in our intestines into mammalian lignans, including one called enterolactone that is thought to protect against breast and other hormone-dependent cancers as well as heart disease. In addition to whole grains, nuts, seeds and berries are rich sources of plant lignans, and vegetables, fruits, and beverages such as coffee, tea and wine also contain some. When blood levels of enterolactone were measured in 857 postmenopausal women in a Danish study published in the Journal of Nutrition, women eating the most whole grains were found to have significantly higher blood levels of this protective lignan. Women who ate more cabbage and leafy vegetables also had higher enterolactone levels.
Significant Cardiovascular Benefits for Postmenopausal Women
Eating a serving of whole grains, such as buckwheat, at least 6 times each week is an especially good idea for postmenopausal women with high cholesterol, high blood pressure or other signs of cardiovascular disease (CVD).
A 3-year prospective study of over 220 postmenopausal women with CVD, published in the American Heart Journal, shows that those eating at least 6 servings of whole grains each week experienced both:
The women's intake of fiber from fruits, vegetables and refined grains was not associated with a lessening in CVD progression.
- Slowed progression of atherosclerosis, the build-up of plaque that narrows the vessels through which blood flows, and
- Less progression in stenosis, the narrowing of the diameter of arterial passageways.