By Susan Kundrat, M.S., R.D.,L.D
Every year since 1918, cardiovascular disease has been the leading cause of U.S. mortality, leading health professionals and consumers to search for diet and lifestyle changes to enhance heart health. Not too many years ago, we focused on reducing saturated or “bad” fats in the diet. Today’s recommendations advise increasing the consumption of “healthy” fats to enhance heart health.
Fatty fish (salmon, tuna, mackerel, sardines and herring) and their oils are the primary sources of long-chain omega-3 fatty acids, eicosapentaenoic (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6). Fish and fish oils reduce triglycerides and platelet aggregation. Moderate fish consumption (one to two servings per week) has been associated with reduced coronary-heart-disease mortality and reduced death from non-sudden myocardial infarction (MI).
In a study published in the Jan. 17, 2001 issue of the Journal of the American Medical Association, Boston-based Harvard University researchers following nearly 80,000 women ages 34 to 59 in the Nurses’ Health Study found women who ate fish five times a week reduced their risk of stroke by 52%, while consuming fish two to four times per week or once per week decreased their risk by 27% and 22%, respectively. Clearly, the benefits of eating fatty fish may outweigh the changes seen in blood lipids.
In the “2000 American Heart Association Dietary Guidelines,” published in the Oct. 31, 2000 issue of Circulation, researchers note the benefits of omega-3 fatty acids as “a reduction in sudden death, decreased risk of arrhythmia, lower plasma triglyceride levels and a reduced blood-clotting tendency.” The guidelines recommend eating at least two servings of fish per week for cardioprotective effects. Other good omega-3 fatty-acid sources include flaxseed and flaxseed oil, canola oil, walnut oil, soybean oil, soybeans and nuts.
Many studies also have demonstrated a positive effect on heart health with omega-3 fatty-acid supplementation. In November 2000, the FDA announced a decision to allow a qualified health claim about EPA and DHA in dietary supplements and a reduced coronary heart-disease (CHD) risk. According to the FDA, “The scientific evidence about whether omega-3 fatty acids may reduce the risk of coronary heart disease is suggestive, but not conclusive. Studies in the general population have looked at diets containing fish and it is not known whether the (entire) diet or omega-3 fatty acids in fish may have a possible effect on a reduced risk of CHD. It is not known what effect omega-3 fatty acids may or may not have on risk of CHD in the general population.” The FDA added that supplements may not recommend or suggest in labeling, or under ordinary conditions of use, daily intakes exceeding 2 grams EPA and DHA omega-3 fatty acids.
Many consumers shy away from high-fat, calorie-dense nuts. But in the early 1990s, researchers began publishing studies linking nut intake with cardiovascular health. Walnuts, almonds, macadamia nuts, pistachios, pecans and hazelnuts can significantly reduce both total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol when consumed as part of a low-saturated-fat, low-cholesterol diet.
A study published in the April 24, 2000 issue of the Archives of Internal Medicine found that when compared with a typical American diet, a diet high in monounsaturated fats from macadamia nuts lowered TC, LDL and HDL each by 5% and triglycerides by 10%. These results were similar to those achieved with the American Heart Association Step 1 Diet, except triglycerides increased by 8%.
In another study, published in the January 2000 issue of the Journal of Nutrition, 40 Japanese men and women in a controlled, single-blind, cross-over study added 43 to 57 grams per day of walnuts to their diet for four weeks (with decreased fat consumption from other foods). The walnut diet decreased TC by 4% in men and 5% in women; LDL decreased in women by 11%.
A series of studies following Seventh-Day Adventists also found a decreased risk of nonfatal MI (22% less) and CHD (24% less) in participants who consistently ate nuts at least one to four times per week compared to those who ate nuts less than once a week.
Stanol and sterol esters
In September 2000, the FDA authorized label health claims about the role of plant sterol or plant stanol esters in reducing CHD risk. Plant sterols are present in small amounts in many fruits, vegetables, nuts, seeds, cereals, legumes and other plant sources. Plant stanols occur in even smaller quantities from similar sources.
Studies show 1.3 grams per day of plant sterol esters or 3.4 grams per day of plant stanol esters in the diet are needed for a significant cholesterol-lowering effect. To qualify for the health claim, a product must contain at least 0.65 grams of plant sterol esters per serving or at least 1.7 grams of plant stanol esters per serving.
Functional foods, such as the spreads Benecol® (with stanols), made by McNeil Consumer Healthcare, Ft. Washington, PA, and Take Control® (with sterols), made by Unilever’s Lipton unit, Englewood Cliffs, NJ, contain these esters. Studies on Benecol and Take Control have demonstrated LDL cholesterol reductions of 14% to 17%.
Conjugated linoleic acid
Conjugated linoleic acid (CLA) is an omega-6 fatty acid found in milk, dairy products and beef. It has been researched for its potential cancer-fighting qualities and was most recently linked to body-fat reduction in overweight and obese humans. In addition, several animal studies link CLA to beneficial effects on plasma lipoproteins and aortic atherosclerosis. It has a positive effect on plasma triglyceride, plasma LDL-cholesterol (LDL-C) and LDL-C:HDL-C ratios in animal studies.
Watch for trans
Trans fats are getting a lot of attention of late — not for heart-health-promoting qualities, but rather because they raise blood cholesterol levels. Trans fatty acids, or “trans fats,” are made during partial hydrogenation of vegetable oils. Like saturated fat, trans fat raises the LDL-C in the blood, increasing CHD risk. They are primarily found in vegetable shortenings, certain frying fats, hard margarines and products that use these as ingredients.
According to the FDA, the daily U.S. trans-fat intake is 5 grams per person, compared to 25 grams of saturated fat. The FDA has proposed that the amount of trans fat per serving be added to the amount of saturated fat per serving so that the amount and percent Daily Value per serving on the Nutrition Facts panel reflects the sum of the two. The FDA also has proposed limits on trans fat for several nutrient-content label claims.
Susan Kundrat, M.S., R.D., L.D., is the owner of Nutrition on the Move, a sports and wellness nutrition consulting business in Champaign, IL. She also is an outreach dietitian for the University of Illinois Functional Foods for Health Program, Urbana-Champaign.
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