Whole Grains Wage War Against Cancer

A landslide of health benefits are linked with eating whole grains. One in particular is whole grains’ potential for fending off cancer, a disease that touches more than 11 million Americans. FDA has backed up whole grains’ cancer-fighting status with an approved health claim, “Diets rich in whole-grain foods and other plant foods and low in total fat, saturated fat and cholesterol may reduce the risk of heart disease and some cancers.”

Although studies have linked whole grains with protection against many types of cancer—colorectal, gastric, mouth and throat, digestive tract, hormone-related, pancreatic, and endometrial—it’s colorectal cancer that catches the spotlight. A recent expert report from the American Institute for Cancer Research, Washington, D.C., “Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective,” found probable evidence that foods containing dietary fiber, such as whole grains, can decrease the risk of developing colorectal cancer. In a May 2007 study in the AmericanJournal of Clinical Nutrition (85(5):1,353-1,360), researchers studied data for nearly half a million middle-aged men and women enrolled in the NIH-AARP Diet and Health Study, and discovered grain fiber as well as whole grains were likely to reduce the risk of colorectal cancer.

The whole package

Whole grain’s isolated constituents, such as dietary fiber, vitamins, minerals and plant compounds, do not fully explain the cancer-preventive effects, leading scientists to believe that the unique nutrients found in whole grains provides a “package” for delivering cancer protection. Whole grains may fight cancer through many mechanisms, including large-bowel effects, antioxidant activity, alterations in blood glucose levels, weight loss, hormonal effects and the power of biologically active compounds.

Whole grains are chock full of fermentable carbohydrates, such as dietary fiber, resistant starch and oligosaccharides. These undigested carbohydrates increase fecal weight, speed transit time and are fermented in the colon by intestinal microflora into short-chain fatty acids that are linked to lower cancer risk.

Researchers increasingly suspect insulin may play a role in cancer. Colon-cancer incidence has been linked to higher levels of blood glucose, insulin and body weight. Since food structure is more significant to glycemic response than dietary-fiber content, it makes sense that whole grains produce a lower glycemic response than refined grains. When comparing plasma insulin response in grains, a stepwise effect has been observed, with increases in insulin response as the grain is more refined: whole grains less than cracked grains less than coarse flour less than fine flour.

Whole grains’ abundant antioxidants may work to prevent cancer, protecting DNA from oxidative stress, damage and mutation that can lead to cancer. In the mix are soluble antioxidants, including phenolic acids, flavonoids, tocopherols and avenanthramides. Largely, insoluble antioxidants are bound as cinnamic acid esters to arabinoxylan side chains of hemicellulose. Insoluble grain fiber also possesses antioxidant activity—in the colon, enzymes free the bound phenolic acids so that cells may absorb it to gain antioxidant protection and enter the circulation. Thus, whole grains provide antioxidant protection over a long period through the entire digestive tract. Vitamin E also acts as a powerful antioxidant, and selenium functions as a cofactor for glutathione peroxidase, an enzyme that protects against oxidative tissue damage and suppresses cell proliferation.

Intestinal bacteria convert lignans, whole grains’ hormonelike diphenolic phytoestrogens, to compounds with weak estrogenic and antioxidant activity. They have been shown to influence intracellular enzymes, protein synthesis, growth-factor action, malignant-cell proliferation, differentiation and angiogenesis in a cancer-protective way.

Whole grains also contain several antinutrients, including protease inhibitors, phytic acid, phenolics and saponins. Such antinutrients were thought to have only negative nutritional effects, but now scientists believe that, in proper amounts, some may work as cancer inhibitors by preventing the formation of carcinogens and blocking the interaction of carcinogens with cells.

Whole grains in the food supply

The 2005 Dietary Guidelines for Americans recommends Americans make half or more of their grains whole grains (the equivalent of three servings per day or more for ages 9 and older). According to the Whole Grains Council, Boston, “whole grains, or foods made from them, contain all the essential parts and naturally occurring nutrients of the entire grain seed. If the grain has been processed, the food product should deliver approximately the same rich balance of nutrients that are found in the original grain seed.” The list of whole grains approved by the Council includes amaranth, barley, buckwheat, corn (including whole cornmeal and popcorn), millet, oats (including oatmeal), quinoa, rice (both brown rice and colored rice), rye, sorghum (also called milo), teff, triticale, wheat (including varieties such as spelt, emmer, faro, einkorn, Kamut, durum, bulgur, cracked wheat and wheat berries) and wild rice.

The Dietary Guidelines calls for “ounce-equivalents” of whole grains—a confusing measurement for consumers. The Whole Grains Council created a packaging symbol called the Whole Grain Stamp to help consumers identify products that contain 16 grams (equivalent to 1 serving) or 8 grams of whole grains. More than 1,800 different products in the United States now display Whole Grain Stamps.

With whole grains racking up so many health benefits, consumers’ interest has nowhere to go but up.

Sharon Palmer is a registered dietitian with 16 years of experience in health-care and foodservice management. She writes on food and nutrition for newspapers, magazines, websites and books. Palmer makes her home in Southern California and can be reached at [email protected].

Market Snapshot

Going With the Grain

Whole grains have been wholeheartedly embraced by consumers. In the 2007 International Food Information Council Survey, “Consumer Attitudes Toward Functional Foods/Foods for Health,” when consumers were asked unaided to name a specific food or component with health benefits, whole grains came out No. 4 on their list. According to Chicago-based Mintel’s Global New Products Database, in 2006, nearly 10 times as many new whole-grain products were introduced as in the year 2000.