Health Benefits of Whole Grains
Author: Winston Craig, MPH, PhD, RD.
Going With the Grains
Fruit and vegetables, nuts and soybeans have received a lot of publicity recently because of their health-promoting properties and protection against heart disease, cancer and other chronic diseases. The value of grains in the diet has been somewhat overshadowed by all of the attention given to these other food groups. The foundation of the Food Guide Pyramid consists of the bread, cereal, rice and pasta group, foods rich in carbohydrates. Based upon the number of servings recommended for the various food groups, the breads/cereals group should comprise about 40 percent of our diet.
Many people who go on a weight-loss diet greatly reduce or totally eliminate all grains from their diet. The main reason for this bizarre food selection is the promotion of low-carbohydrate, high-protein diets espoused in best-selling books such as The Zone, Protein Power, and Dr Atkins New Diet Revolution.
The Food Guide Pyramid suggests we should consume 6-11 servings a day of the bread/cereal group. Nutrition scientists recommend at least three of those servings should be whole grains. However, only about five percent of all the grain products that Americans eat are in the whole grain form. Most of the health-promoting compounds are located in the nutrient-rich bran and germ.
With the elimination of the bran and germ, refined grains are heavily stripped of their fiber, vitamins, and trace minerals, as well as the lignans (phytoestrogens), phytosterols, phytates, flavonoids, and phenolic compounds. Whole grains (and especially the oil-rich germ) are a rich source of vitamin E, an antioxidant that protects against heart disease. Grains, especially rye and barley, are unique in that they contain more tocotrienols than any other food group. Tocotrienols are inhibitors of cholesterol synthesis. Phytosterols interfere with cholesterol absorption, while the fiber and phytates in whole grains protect against colon cancer. The trace elements selenium, copper and manganese are necessary for various enzymes that have antioxidant functions. Ferulic acid, caffeic acid, chlorogenic acid, p-couramic acid and other phenolic acids which are abundant in the bran layer have strong antioxidant activity. Many of the protective compounds in whole grains are also in fruit and vegetables but some substances, such as phenolic acids, are more concentrated in whole grains.
|Nutrient Losses During the Refining of Whole Wheat|
Choosing refined grains exclusively could be costing people their health. Whole grains can protect against cancer (especially colon cancer), heart disease, diabetes, and gastrointestinal disorders. Oats and barley are especially known for their ability to lower blood cholesterol levels. In the Iowa Women's Health Study, those who consumed at least three servings of whole grains/day were 30 percent less likely to die of a heart attack than those who averaged less than one serving of whole grains/day. In another study, a 10 gram increase in cereal fiber was associated with a 20% reduced risk of heart attacks. In the Nurses' Health Study, a high cereal fiber intake was associated with a 28% lower risk of diabetes. In a review of 45 studies involving 20 cancers, 95% of the studies showed whole grains to be protective. Overall, the risk of most cancers were 20-50% lower in those with a high versus low consumption of whole grains. An additional value of whole grains is that they add texture and a unique flavor to the diet.
If whole grains are so healthy, why do an estimated 80 percent of Americans eat them less than once a day? One reason is that many people have a difficult job figuring out what is whole grain and what is not! Ingredients listed as cracked wheat, multi-grain, wheat flour, and unbleached wheat flour usually refer to refined products. Most pasta is refined, although a few companies make whole grain spaghetti. Many ready-to-eat cereals are refined. The cereals that are whole grain include Cheerios, Granola, Muesli, Grape-nuts, Nutri-Grain, Shredded Wheat, Total, and Wheaties. Pearled barley, cornmeal, couscous, and bulgur are usually refined products while oatmeal and quinoa are whole grain.
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According to a recent Harvard study, foods rich in magnesium such as whole grains, nuts, and green-leafy vegetables provide a measure of protection against type 2 diabetes.