From The November 2000 Issue of Nutrition Science News

Better Diet Cuts Heart Disease Deaths

Heart disease deaths in the United States plummeted by a third between 1980 and 1994. To investigate whether the decrease was due to better health status or better medical care, Frank Hu, M.D., Ph.D., of the Department of Nutrition at Boston's Harvard School of Public Health, conducted a statistical analysis of data obtained from 85,941 women ages 35 to 59 as part of the Nurses' Health Study. Diet and lifestyle factors were first assessed in 1980, then at intervals for the next 10 years.

During this time, the women's diets improved considerably. Between 1980 and 1994, the average daily intake of fish-derived omega-3 fatty acids increased by 180 percent, whole-grain consumption increased by 90 percent, the polyunsaturated/saturated ratio increased by 69 percent, folate consumption increased by 12 percent, and trans fatty acid consumption decreased by 31 percent. Also, the number of times the average woman ate more than one serving of red meat daily declined by a third.

During the 10-year period, the women ate more low-fat and less high-fat dairy products. However, the glycemic load, a measure of how diet raises blood sugar, increased during the time period by 22 percent, which may explain why more women became obese. Higher blood-sugar levels lead to higher insulin levels and consequently more fat storage. The average body mass index (BMI) increased from 24.5 to 26.1, and the prevalence of those overweight rose by 38 percent.

The researchers calculated that the overall dietary improvement resulted in a 16 percent decline in coronary disease incidence. However, the increase in obesity offset this improvement somewhat by increasing the disease rate by 8 percent. A decrease in cigarette smoking may have also contributed to the coronary disease decline.

— New England Journal of Medicine 2000 Aug 24;343(8):530-7.