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Sales of whole-grain food products and dietary fiber have increased significantly since February 2006, when the Food and Drug Administration issued its definition of "whole-grain foods" and a draft guidance for industry on whole-grain label statements
Relative to 2005 data, sales of pasta increased by 26%, white bread products 55%, and fresh bagel goods 30%, according to the Whole Grains Council. In addition, total feed grain (corn, sorghum, barley, oats) use and domestic use experienced moderate increases between 2001 and 2006, while disappearance data indicate a 17% increase in food, alcohol, and industrial use of these grains.
The importance of whole grains in supporting improved health is emphasized in the government’s 2005 Dietary Guidelines for Americans and Healthy People 2010 reports and supported by public health experts in the United States and Europe and by emerging clinical data.
Epidemiological evidence suggests that healthy lifestyles include whole-grain foods. The inclusion of three servings of whole grains/day may reduce the risk of type 2 diabetes, cardiovascular disease, obesity, and possibly certain types of cancer. While each of these pathologies is associated with multiple risk factors and etiologies, concerted dietary intervention that includes whole grains may be important based on a number of clinical endpoints.
• Diabetes. Dietary intervention studies suggest that regular consumption of whole grains and legume foods may be important in post-prandial glycemic control among type 2 diabetics. Large prospective studies since 2000 suggest a significant negative risk of developing type 2 diabetes when three servings of whole grains are consumed daily. An 8-year prospective cohort study of more than 41,000 women indicated that a higher weekly consumption of whole grains, calcium, magnesium, and dietary fiber was associated with a lower risk of type 2 diabetes.
• Cardiovascular Disease. Epidemiological and experimental data suggest that consumption of whole grains may be more cardioprotective than other commonly consumed foods, and that this benefit may be independent of dietary fiber. The possible physiological mechanisms to explain these benefits remain speculative. Some of the speculation focuses on a variety of fat- and water-soluble components, such as phenolics, phytosterols, and lignans. Their functions may include reducing insulin resistance in the case of diabetes; modulating vascular and endothelial inflammatory responses in the case of CVD; and assisting in weight management in the case of obesity. Each of these conditions is a risk factor related to CVD.
• Obesity. Several studies investigating a possible relationship between whole grain consumption and weight management yielded mixed results. Data from the Nurses’ Health Study and Health Professionals Follow-Up Study suggest no differences in body mass index (BMI) between low and high quintiles of whole-grain intake. On the other hand, data from the Framingham Offspring Study and Iowa Women’s Health Study indicated a significant trend of BMI reduction among higher whole-grain consumption participants. A smaller, short-term study among overweight or obese diabetics indicated that the inclusion of whole grains can improve insulin sensitivity.
• Cancer. A large, 15-year cohort study among women assessed a possible relationship between whole-grain consumption and incidence of colorectal cancer. The relative risk of colon cancer was significantly reduced among those consuming 4.5 or more servings of whole grains/day but no differences in the incidence of colorectal cancer or rectal cancer among the study groups.
These kinds of results remain controversial, since there is considerable individual variability in response to whole grains and dietary fiber and the incidence of colorectal cancer. They also emphasize the importance of prospective epidemiological research among study groups that fully represent the dynamics of the general population, and the importance of understanding the physiochemical nature of dietary components. Clearly, dietary fiber is not equivalent to whole grains.
• Making Changes. Regular consumption of whole grains is part of a healthy lifestyle. That lifestyle change begins in the schools with the introduction of favorable sensory characteristics of whole-grain products. Continued clinical research, development of new whole-grain products, implementation of novel food technologies, and improved consumer education represent strong opportunities that will provide a new life for whole grains and a better quality of life for consumers.
References for the studies mentioned above are available from the authors.
by Roger Clemens, Dr.P.H.,
Special Projects Advisor, ETHorn, La Mirada, Calif.
by Peter Pressman, M.D.,
Attending Staff, Internal Medicine, Cedars-Sinai Medical Center, Los Angeles, Calif.