The U.S. Department of Agriculture’s Dietary Guidelines for Americans (DGA) are designed to promote health and reduce the risk of chronic diseases, but their impact on existing disease hasn’t been adequately studied, according to researchers from the Human Nutrition Research Center on Aging at Tufts University in Boston (Am J Clin Nutr. 2009;90: 193-201). More specifically, the effect of overall adherence to the guidelines on the progression of atherosclerotic lesions in the coronary arteries has been found to be lacking.

But investigators can now report that DGA adherence is associated with reduced progression of coronary artery atherosclerosis in women with established coronary artery disease (CAD)—and that some DGA recommendations are more beneficial than others in this respect.

The researchers evaluated atherosclerotic progression and patient compliance with 20 key DGA recommendations in 224 postmenopausal women with CAD. DGA compliance was measured using the DGA Adherence Index (DGAI), which weights each dietary component equally. In addition, researchers calculated a modified score by weighting each component based on its relation to atherosclerotic progression.

On average, the women adhered to about two thirds of the key DGA recommendations. After a mean follow-up of 3.3 years, researchers found no significant association between coronary artery narrowing and DGA compliance as measured by the DGAI. However, adherence to the dietary recommendations based on their specific connection with heart disease risk was significantly associated with less narrowing of the arteries. Complying with the intake recommendations for whole grains, total fat, and cholesterol was associated with the least narrowing of the arteries.