Whole Grain Health Benefits

Numerous studies suggest that eating whole grains contributes to better health, and may help protect against cancer, cardiovascular disease, diabetes, and obesity. The USDA recommends consuming three servings of whole grains each day, but most Americans fall short of that goal, consuming and average of only 1 serving per day.

Whole grains and cancer

Substantial scientific evidence indicates that whole grains reduce cancer risk. The key cancer-fighting agents in whole grains are dietary fiber. Additional studies have found that higher serum insulin levels are associated with increased risk of colon, breast, and possibly other cancers - and whole grains appear to reduce these insulin levels.

Dietary factors, such as fiber, vitamin B6 and phytoestrogen intake, and lifestyle factors such as exercise, smoking and alcohol use do not by themselves explain the apparent cancer-fighting affect, suggesting that it is the whole-grain "package" that is effective.

Whole grains also provide selenium, though selenium content of grains varies depending on soil selenium content. One clinical trial using a dose of 200 mg/day of selenium in 1,312 patients, found a 37% reduction in cancer incidence and a 50% reduction in cancer mortality, including substantial reductions in lung, prostate and colorectal cancers (Clark et al, 1996).

Vitamin E, which is found in whole grains, is believed to be a cancer inhibitor that prevents carcinogens from forming. Whole grains also contain several antinutrients, such as protease inhibitors, phytic acid, phenolics and saponins, which until recently were thought to have only negative nutritional consequences. Some of these antinutrient compounds may act as cancer inhibitors by preventing the formation of carcinogens and by blocking the interaction of carcinogens with cells.

Whole grains and cardiovascular disease

Cardiovascular disease (CVD) is the number one cause of death and disability of both men and women in the United Stats. Strong epidemiological and clinical evidence links consumption of whole grains to a reduced risk for coronary heart disease (Anderson, 2002). There are many theories on how whole grains help cut the risk of cardiovascular disease. Whole grains are rich in compounds such as tocotrienols, a form of vitamin E, which play an important role in disease prevention, including reducing the risk of heart disease (Slavin et al, 1999). Whole grains are also a source of plant sterols, such as beta-sitosterol, which can lower cholesterol. Whole grains are an excellent source of dietary fiber, resistant starch and oligosaccharides, which help to lower serum cholesterol (Hara et al, 1999).

Whole grains and diabetes

Whole grains are known to affect glucose and insulin responses, partly due to their slow digestibility. Several studies have shown that cereal fiber intake is associated with reduced risk for diabetes.

Intake of fiber from whole-grain cereals has also been found to be inversely related to type 2 diabetes. In a long-term study of almost 90,000 (Salmeron et al, 1997a) women and in a similar study of about 45,000 men (Salmeron et al, 1997b), researchers found that those with higher intakes of cereal fiber had about a 30% lower risk for developing type 2 diabetes, compared to those with the lowest intakes.

Whole grains are good sources of dietary magnesium, fiber and vitamin E, which are involved in insulin metabolism. Relatively high intakes of these nutrients from whole grains may prevent hyperinsulinemia. Whole grains may also influence insulin levels through beneficial effects on satiety and body weight.

Whole grains and obesity

Preliminary studies suggest an association between whole grain intake and the regulation of body weight (Pereira et al, 2002.) Several factors may explain the influence of whole grains on body weight regulation. The high volume, low energy density and the relatively lower palatability of whole grain foods may promote satiation. Whole grains may delay hunger from returning after a meal. Although preliminary evidence suggests whole grains may influence body weight regulation, additional epidemiological studies and clinical trials are needed.

Whole grains and all-cause mortality

Several epidemiological studies suggest whole grains reduce the risk for all-cause mortality or all-cause death. In the Iowa Women's Health Study, whole grains and cereal fiber lowered all-cause death in postmenopausal women (Jacobs et al, 1999; Jacobs et al, 2000a), and a Norwegian study showed a lower mortality rate for men and women with a high whole grain bread intake (Jacobs et al, 2000b). Liu et al (2003) reported that both total mortality and Cardio Vascular Disease-specific mortality were inversely associated with whole-grain but not refined-grain breakfast cereal intake in the Physicians' Health study.

Source: The Goodness of Whole Grains, Gary Fulcher and Joanne Slavin, Department of Food Science and Nutrition, University of Minnesota.