Healthy Eating:
They Know They Should, but Do They?
Most people likely know that their diet can affect their health, but that doesn’t mean that they are eating well. In fact, the American diet has undergone an unhealthy shift in recent decades.1 The prevalence of obesity has risen more than 60% since 1993.2 Sixty-four million US adults are obese, and more than 135 million are overweight.2 Over 33% of adult women are obese.3 And it doesn’t appear that such trends will reverse any time soon, as 16% of US adolescents (aged 12 to 19 years) are overweight.3 This issue of Know Her Heart will present an overview of what your patients should be eating for heart health.

Diet and Coronary Heart Disease

The association of diet and coronary heart disease (CHD) has been studied for a century.4 In recent decades, our understanding of foods that promote cardiac health has grown substantially, and, while the optimal diet has not yet been delineated, solid and more specific evidence about the relationship between diet and CHD is available.4,5

An atherogenic diet is a major and modifiable risk factor for CHD.5 High intakes of saturated fats are associated with high rates of CHD.5,6 Populations whose diets are high in fruits, vegetables, whole grains, and unsaturated fatty acids appear to be at a baseline CHD risk that is lower than can be explained by traditional risk factors alone.5

Evidence-based guidelines from the American Heart Association (AHA) include the recommendation to consistently encourage a heart-healthy diet (SOR: B).7 A 2002 journal article summarized the most important CHD-preventive dietary recommendations of the European Society of Cardiology, the AHA, the National Cholesterol Education Program, and a number of studies4:

  • Keep an energy balance, indicated by a body mass index <25.
  • Consume <10% of caloric energy from saturated fat.
  • Consume <2% of caloric energy from trans fat.
  • Eat (fatty) fish at least once per week.
  • Eat ≥400 g of vegetables and fruits per day.
  • Limit salt consumption to <6 g/day.

According to the authors, following these recommendations, along with not smoking, drinking alcohol only in moderation, and engaging in moderate to vigorous physical activity, could eliminate CHD to a large extent in the population younger than 70 years.4

Adult Treatment Panel III Recommendations

The Adult Treatment Panel (ATP) III recommends a multifactorial lifestyle approach to reducing CHD risk called “therapeutic lifestyle changes” (TLC), which include the following components5:
  • Reduced intakes of saturated fats and cholesterol (SOR: B)
  • Therapeutic dietary options for further lowering low-density lipoprotein cholesterol (LDL-C) (SOR: B)
  • Weight reduction (SOR: B)
  • Increased regular physical activity (SOR: B)
The table below presents the dietary aspects of TLC.



*Trans fatty acids should also be kept at a low intake.
†ATP III allows an increase of total fat to 35% of total calories and a reduction in carbohydrates to 50% for persons with metabolic syndrome. Any increase in fat intake should be in the form of either polyunsaturated or monounsaturated fat.
‡Carbohydrates should derive predominantly from foods rich in complex carbohydrates, including grains—especially whole grains—fruits, and vegetables.
For a detailed discussion of TLC, see the full ATP III report.

USDHHS Key Recommendations

In addition to lowering intake of saturated and trans fats, the US Department of Health and Human Services (USDHHS) recommends encouraging people to increase their intake of certain food groups. Their key recommendations are6:
  • Consume a sufficient amount of fruits and vegetables compatible with energy needs—eg, 2 cups of fruit and 2.5 cups of vegetables per day for a 2000-calorie intake.
  • Choose a variety of fruits and vegetables each day, selecting from all 5 vegetable subgroups—dark green, orange, legumes, starchy vegetables, and other vegetables—several times per week.
  • Consume 3 or more ounce-equivalents of whole-grain products daily, with the rest of the recommended grains coming from enriched or whole-grain products. Whole grains should represent at least 50% of total consumption. (See note below.)
  • Consume 3 cups per day of fat-free or low-fat milk or equivalent milk products. (See note below.)
NOTE: The Harvard School of Public Health (HSPH) takes exception with the suggestion that it is acceptable for half of the daily grains to be in the form of refined starches, which add empty calories, have adverse metabolic effects, and increase the risks of diabetes and heart disease. HSPH also disagrees with the recommendation to consume 3 servings of dairy products per day. According to HSPH, 3 glasses of low-fat milk contain more than 300 calories, and such a recommendation ignores the fact that millions of Americans are lactose intolerant, the lack of evidence of a link between dairy consumption and osteoporosis prevention, and the possible increased risk for ovarian and prostate cancer associated with dairy products.8

For a detailed discussion of USDHHS recommendations, see the Dietary Guidelines for Americans 2005.

Cardioprotective Effect of Omega-3 Fatty Acids

The cardioprotective effect of omega-3 fatty acids for women and men has been shown in epidemiologic and observational studies.9-12 One of the few studies conducted only with women showed an inverse association between omega-3 fatty acid intake and CHD.12
  • After adjusting for known CHD risk factors, the relative risk of CHD was 0.79 for women who consumed fish 1 to 3 times per month and 0.66 for women who consumed fish 5 or more times per week, compared with women who ate fish less than once per month.
  • Similarly, risk reduction was also noted when women were stratified by omega-3 fatty acid intake: women in the highest quintile of intake (quintile 5) had a relative risk of CHD of 0.67; risk reduction in quintiles 1-4 was 1.00, 0.93, 0.78, and 0.68, respectively.
The AHA states that omega-3 fatty acid supplementation may be considered as an adjunct to diet for high-risk women (SOR: B).7

Food Pyramids

Traditionally, a food pyramid has been a diagrammatic representation of a healthy diet that places the staple foods that should serve as the diet base at the wider bottom of the pyramid and the foods that should be consumed less frequently at the narrow top of the pyramid. In 2005, the USDA replaced their old food pyramid with a new one (“My Pyramid”) that divides the pyramid vertically, so all sections representing food groups extend from the point to the base (see www.mypyramid.gov). This new stratification does not specify serving sizes or amounts because the USDA now recognizes that “one size does not fit all.” Therefore, the “My Pyramid” Web site provides an interactive feature in which you enter your age, sex, and approximate activity level, and an individualized food-pyramid diet plan is displayed.

HSPH nutrition experts have created their own food pyramid (shown in the figure below) to address the flaws they see in the USDA pyramid.8 According to the HSPH pyramid, the foundation of any healthy diet is daily exercise and weight control.



For a more detailed discussion of the HSPH Healthy Eating Pyramid, see Food Pyramids.



References
1. Eyre H, Kahn R, Robertson RM, and the ACS/ADA/AHA Collaborative Writing Committee. Preventing cancer, cardiovascular disease, and diabetes: a common agenda for the American Cancer Society, the American Diabetes Association, and the American Heart Association. Circulation. 2004;109:3244-3255. 2. American Heart Association. Heart Disease and Stroke Statistics—2006 Update. Dallas, Tex: American Heart Association; 2006. 3. Hedley AA, Ogden CL, Johnson CL, Carroll MD, Curtin LR, Flegal KM. Prevalence of overweight and obesity among US children, adolescents, and adults, 1999-2002. JAMA. 2004;291:2847-2850. 4. Kromhout D, Menotti A, Kesteloot H, Sans S. Prevention of coronary heart disease by diet and lifestyle: evidence from prospective, cross-cultural, cohort, and intervention studies. Circulation. 2002;105:893-898. 5. National Cholesterol Education Program. Third report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III): final report. National Institutes of Health and National Heart, Lung, and Blood Institute, NIH publication no. 02-5215. 2002. 6. US Department of Health and Human Services, US Department of Agriculture. Dietary Guidelines for Americans 2005. 6th ed. Washington, DC: US Government Printing Office; 2005. 7. Mosca L, Appel LJ, Benjamin EJ, et al. Evidence-based guidelines for cardiovascular disease prevention in women. Circulation. 2004;109:672-693. 8. Harvard School of Public Health. Food pyramids. Available online at: http://www.hsph.harvard.edu/nutritionsource/
Printer%20Friendly/Food%20Pyramids.pdf. Accessed April 4, 2007. 9. Albert CM, Hennekens Ch, O’Donnell CJ, et al. Fish consumption and risk of sudden cardiac death. JAMA. 1998;279:23-28. 10. Kromhout D, Bosschieter EB, de Lezenne Coulander C. The inverse relation between fish consumption and 20-year mortality from coronary heart disease. N Engl J Med. 1985;312:1205-1209. 11. Kromhout D, Feskens EJ, Bowles CH. The protective effect of a small amount of fish on coronary heart disease mortality in an elderly population. Int J Epidemiol. 1995;24:340–345. 12. Hu FB, Bronner L, Willett WC, et al. Fish and omega-3 fatty acid intake and risk of coronary heart disease in women. JAMA. 2002;287:1815-1821. 13. Willett WC, Skerrett PJ. Eat, Drink, and Be Healthy: the Harvard Medical School Guide to Healthy Eating. Reprint edition. New York, NY: Free Press; 2005.