Healthnotes Newswire (October 19, 2000)—A “prudent” diet—high in fruits, vegetables, legumes, whole grains, fish, and poultry—has been linked with protection against cardiovascular disease in women and men, according to two new studies published in the current issue of the American Journal of Clinical Nutrition. On the other hand, the standard American diet—high in red meat, processed meat, refined grains, sweets and dessert, French fries, and high-fat dairy products—was linked with significantly increased risk of cardiovascular diseases, such as heart attacks and strokes.
In the first study,1 39,127 female healthcare professionals were interviewed and observed for five years as part of the Women’s Health Study. The primary outcome studied was the occurrence of cardiovascular disease, including nonfatal heart attacks, stroke, and coronary artery disease requiring surgery. The authors observed a significant link between increased consumption of fruits and vegetables and decreased risk of cardiovascular disease, particularly heart attacks. Women who ate 5–10 servings of fruit and vegetables per day had approximately 30% less risk of cardiovascular disease than did women who ate 2.5 servings per day.
However, high fruit and vegetable intake goes hand in hand with other healthful lifestyle habits. After the researchers adjusted their results to account for both protective lifestyle habits (such as exercise) and cardiovascular disease risk factors (such as smoking), the high fruit and vegetable diet afforded only a 15% reduction in cardiovascular disease risk compared to the effect of a low fruit and vegetable diet. While not statistically significant, these adjusted results identify an important trend and support a recommendation for higher intakes of fruit and vegetables for people at risk of cardiovascular disease.
In a parallel study,2 44,875 male healthcare professionals were interviewed and observed for eight years as part of the Health Professionals Follow-Up Study (HPFS). The primary outcome studied was the occurrence of heart attacks resulting from atherosclerosis (hardening of the arteries). Two dietary patterns were identified: the “prudent diet” pattern, and the “typical American diet” pattern. The men who ate the highest percentage of their foods from the “prudent” diet category were able to reduce their risk of fatal and nonfatal heart attacks by 30% compared to men who ate the fewest foods in the “prudent” category. An opposite trend was observed for the “typical American diet” pattern. Men who ate the highest percentage of their foods from the “typical American diet” category increased their risk of a heart attack by 64%, compared with men who ate the fewest foods in that category.
Although people who eat a standard American diet are more likely to smoke and less likely to exercise—behaviors linked with increased risk of heart disease—the authors of the HPFS report accounted for these trends in calculating the risks associated with the two diets. Similarly, people eating a prudent diet are more likely to engage in other protective behaviors, such as taking nutritional supplements or exercising. The researchers meticulously controlled for the influences of these behaviors as well in interpreting their data. The study results clearly suggest that the two major dietary patterns—prudent diet and typical American diet—were able to predict the risk of atherosclerosis, independent of the effects of several known beneficial or harmful nutrients and behaviors.
Mediterranean and Asian populations have a very low incidence of atherosclerosis compared with Americans. These low rates are attributed primarily to high intakes of fruit, vegetables, legumes, whole grains, and fish, and low intakes of red meat, high-fat dairy products, and other animal products, in traditional Mediterranean and Asian diets.3 4 However, because many other risk factors vary from country to country, it has not been possible to firmly attribute the lower atherosclerosis rates in other cultures strictly to differences in diet. The current studies highlight the similarities between the prudent diet and traditional Mediterranean and Asian diets, and strengthen the case that these diets prevent heart disease. They also highlight the importance of a whole-foods diet in the prevention of disease.
While many studies have examined the association between intakes of individual nutrients or foods and the risk of cardiovascular disease, until now few have evaluated the relation of overall dietary patterns to risk.5 Drs. David R. Jacobs, Jr., and Maureen A. Murtaugh of the School of Public Health at the University of Minnesota caution against the tendency to focus on dietary supplements or formulated functional foods for the provision of nutrients. “Food is not simply an empty vessel carrying single nutrients such as calcium,” they wrote in an editorial accompanying the new studies, “it is the ultimate source of all nutrients.”6 In the real world, people do not eat isolated nutrients, but rather meals consisting of a variety of foods with complex combinations of nutrients that may be interactive or synergistic. Previous studies on diet and cardiovascular disease have focused primarily on individual nutrients or foods. It should be noted that in many of these studies, individual nutrient supplements, such as folic acid, have reduced risk factors for heart disease7 8 9 and may well prove to reduce the risk of heart disease itself. The new studies are among the first to explore the role of overall dietary patterns in the prevention of cardiovascular disease.
As Americans continue to grow fatter and to consume less healthful diets,10 11 these new studies sound a much needed wake-up call. Whether Americans will indeed wake up and heed the call remains to be seen. Cardiovascular disease remains the leading cause of death in the United States.12References