Q: I’ve been hearing a lot lately about the benefits of whole
grains. Why are they so important, and how can I be sure I am
getting enough?
Q: I’ve been hearing a lot lately about the benefits of whole grains. Why are they so important, and how can I be sure I am getting enough?
A: “Eat your fruits, vegetables and whole grains”: we hear that phrase so often during our lives that the advice hardly registers. You’ve probably been told about the many benefits of fruits and vegetables – including the vitamins and minerals they contain. But why are whole grains better than refined grains?
All grains (including wheat, oats, rye and barley) grow as kernels. Each kernel has three layers: bran, on the outside; germ, in the center; and endosperm, between the other two layers. The endosperm contains most of the starch; the germ contains the majority of the vitamins, minerals and oils; and the bran contains the bulk of the dietary fiber.
When grains are “refined,” the three layers of the kernel are separated. Whiter, lighter breads such as Italian bread, French baguettes or Wonder Bread are examples of food made from refined grains. They are made primarily from the endosperm, with the bran and germ – along with most of the vitamins, minerals and fiber – discarded. Foods made from refined grains contribute to obesity, heart disease and diabetes.
Many bakers began to add vitamins to flour in the 1930s in an attempt to stem the nutritional-deficiency diseases that surfaced in the early 20th century as the centuries-old process for refining grains continued to improve. And 60 years ago, the Food and Drug Administration mandated the addition of nutrients to refined flour. The list has since expanded to include niacin, thiamin, riboflavin, iron, calcium, vitamin D and folic acid.
Every product made from this “enriched” or “fortified” flour has these nutrients added to meet specific standards. But that still leaves out many other vitamins and minerals, and no added vitamin or mineral can replace the dietary fiber.
Dietary fiber is important for health. It draws water into the intestines, making the feces bulkier and easier to pass; it thereby helps promote intestinal health by reducing the risk of hernias, hemorrhoids and diverticulosis. Fiber also keeps food in the stomach longer, making you feel full and preventing overeating. It also helps boost HDL (“good”) cholesterol and reduce LDL ( “bad”) cholesterol levels in the blood. It used to be said that dietary fiber may protect against cancer of the colon (large intestine). Recent studies have cast some doubt on that, but there is no doubt that fiber protects against heart disease and diabetes. It may also protect against prostate cancer. In other words, fiber still is good for you.
Whole grains are not the only way to get dietary fiber: fruits, vegetables, nuts and seeds are also good sources. But while some of these foods are very high in fiber (beans, prunes, figs), others have surprisingly little (lettuce, celery, cauliflower). It’s hard to get the fiber you need just from fruits and vegetables alone.
Americans should get at least 25 grams of dietary fiber a day; unfortunately, the average American gets less than half that. The U.S. Department of Agriculture’s Food Pyramid Guide calls for six to 11 servings of grains a day; the lower number should suffice for small, sedentary women, the higher one for large, physically active men. Although many experts put the number much higher, the USDA says that at least three of the daily portions should be whole grains – but the average American man eats less than the equivalent of one portion a day.
To get more whole grains, look for products that list them first on their ingredient labels; “100 percent whole grain” foods are best. Don’t be fooled by terms like “multigrain,” “six-grain” or “made with unbleached flour.” They are likely to contain mostly refined grains, as are dark-colored rye and wheat breads that are not labeled whole grain.
Make sure to eat a variety of whole grains. Oats and barley, for example, will give you soluble fiber; whole wheat and corn will supply insoluble fiber. Experiment with new grains, such as bulgur, millet and quinoa. Look for a product that provides at least 5 or 6 grams of fiber per serving; cereals like All-Bran, Fiber One, 100% Bran, Raisin Bran and oatmeal are good examples.
People who are used to refined grains may regard whole grains as a novelty, but it’s really a case of getting back to basics. Remember, our ancestors ate whole grain foods for centuries before grains started to be refined. In the end, whole grains really are worth the fuss.
Submit questions to the Harvard Medical School Adviser at www.health.harvard.edu/adviser. Unfortunately, personal responses are not possible.
The whole story on grain
A kernel of grain has three layers – each with nutritional value. The inner zone is the germ, containing vitamins, minerals and oils. The middle layer is the endosperm, containing most of the starch, along with vitamins and minerals. The outer (bran) layer provides dietary fiber. Refining removes the bran and germ, leaving lighter, whiter fiber, which has lost many of its nutrients.
The simple sugars and other rapidly absorbed carbs in these refined grains may contribute to low HDL (“good”) cholesterol levels and an increased risk of heart disease. But whole grains are another story; these good carbs have a lower glycemic index (that is, they are slowly absorbed, stimulating a gradual release of insulin), and are clearly associated with a reduced risk of diabetes and heart disease, along with probable protection against certain cancers.
As an added bonus, whole grains are filling, and may actually help fight obesity. Research has shown that whole grains appear to reduce the risk of weight gain in women and of abdominal obesity in men.
