LINUS PAULING INSTITUTE RESEARCH REPORT

Meir Stampfer

How to Prevent Heart Disease

A Public Lecture by
Meir Stampfer, M.D., Dr.P.H.

The second and final lecture in the 2004 LPI public lecture series was given on May 3, 2004, by Dr. Meir Stampfer, Professor of Epidemiology and Nutrition and Chair of the Department of Epidemiology at the Harvard School of Public Health. Dr. Stampfer’s presentation, “Primary Prevention of Heart Disease through Lifestyle and Diet,” summarized and discussed several of the important human studies on the prevention of heart disease.

Dr. Stampfer first compared the Dietary Approaches to Stop Hypertension (DASH) diet to the usual American diet and to the “Fruit and Vegetable” diet. The fruit and vegetable diet is rich in fruits, vegetables, and nuts. The DASH diet is similar but also contains fish and low-fat dairy foods and has lower amounts of fats, red meat, and sugar-containing sweets and beverages. The DASH diet was found to be even better at lowering systolic and diastolic blood pressure than the fruit and vegetable diet and at least as effective or more effective than many drugs.

Dr. Stampfer listed five major factors that define a low risk of heart disease:

  • not smoking
  • appropriate body mass index (BMI) of less than 25 kg/m2
  • at least 1/2 hour of vigorous or moderate daily exercise
  • consumption of more than 5 grams per day of alcohol (a standard alcoholic drink—12 fl. ounces of beer, 5 fl. ounces of wine, or 1.5 fl. ounces of distilled spirits—contains about 12 grams of alcohol)
  • compliance with intake recommendations for specific dietary constituents, including:
    • low intake of trans fat, also called partially hydrogenated vegetable oil
    • high intake of marine source omega-3 fatty acids
    • high ratio of polyunsaturated to saturated fats
    • high intake of cereal fiber
    • low glycemic load
    • high intake of folate

Of course, alcohol can be a double-edged sword. While the Health Professionals Follow-up Study found a decreasing relative risk for coronary heart disease with increasing alcohol intake, other studies have reported an increased relative risk for breastcancer associated with alcohol intake in women and a higher death rate from all causes in women who consume more than about two drinks per day. However, there is also evidence that the increased risk of breast cancer in women may disappear if their folate status is adequate.

A number of studies have found that trans fats depress HDL cholesterol levels in serum, which is the “good” cholesterol, and raise levels of LDL cholesterol (the “bad” form), total cholesterol, and triglycerides. Trans fats, consumed as 2% of daily energy, nearly double the risk of heart disease, whereas polyunsaturated fats and monounsaturated fats, consumed as 5% of daily energy, significantly reduce the risk. The risk associated with trans fats is even greater than that linked to saturated fats consumed as 5% of daily energy. The consumption of nuts, which are a good source of unsaturated fats, has been found in at least three high quality studies to be associated with a significantly reduced risk of heart disease. As few as one or two servings of fish each week halves the risk of sudden death from heart disease, probably by preventing fibrillation.

A meta-analysis of nine prospective studies found that high fiber intake was consistently associated with a decreased risk of heart disease. Daily intake of more than about 350 micrograms of folate is also associated with a decreased risk for heart disease. Folate is a B vitamin that has been found to lower high homocysteine levels, which are associated with an increased risk of heart disease.

Dr. Stampfer also discussed the new classification of carbohydrates that emphasizes the biological effect of whole food instead of the traditional designation by chemical structure. He pointed out that different types of carbohydrates differ in their effects on plasma glucose and insulin response. “Glycemic index” refers the ranking of foods based on their effects on plasma glucose levels. The glycemic index of a particular food is determined by comparing its effect on blood glucose to the ingestion of an equivalent amount of glucose or a control carbohydrate. “Glycemic load” refers to this measurement as well as the amount of the food consumed. Dr. Stampfer showed that the risk of heart disease is strongly linked to increased glycemic load, especially in those subjects whose BMI is greater than 23 kg/m2.

Last updated November 2004

Micronutrient Research for Optimum Health

 
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