Nov. 11, 2004 — By now, you’ve likely heard that a diet rich in certain types of fish helps ward off heart attacks and strokes. But if you can’t stand the thought of eating fish take heart — and try walnuts instead.
A new study published in the current issue of the Journal of Nutrition shows that walnuts have a similar beneficial effect on cholesterol levels and C-reactive protein (CRP), an inflammation marker that is strongly associated with atherosclerosis and heart disease.
Walnuts contain alpha-linolenic acid or ALA, an omega-3 fatty acid similar to those found in heart-smart fish, such as salmon. Alpha-linolenic acid has a number of heart-healthy effects, independent of its cholesterol-lowering effects. It has been shown in previous studies to reduce the risk of sudden death from dangerous abnormal heart rhythms.
The study involved 20 men in their late 30s to age 60, and three menopausal women aged 55 to 65. All participants were overweight or obese, had elevations in their cholesterol and “bad” LDL cholesterol levels, and represented typical Americans at high risk for cardiovascular disease.
None of the participants were taking cholesterol-lowering drugs or anti-inflammatory medications, both of which could have altered the results of the study.
Each person was assigned to one of three diets on a rotating six-week basis with a two-week break between each one: The average American diet (AAD) (which served as a control diet); the linoleic acid diet (another omega-3 fatty acid), which included an ounce of walnuts and a teaspoon of walnut oil; and the alpha-linolenic acid diet, which combined the linoleic acid diet with a teaspoon of flaxseed oil. Flaxseed oil is particular high in ALA.
Walnuts Improve Cholesterol Levels
Both the linoleic acid diet and the alpha-linolenic acid diet are high in polyunsaturated fats. Substituting dietary saturated fats with these good polyunsaturated fats lowers “bad” LDL cholesterol.
The study found that C-reactive protein levels dropped nearly 75% when patients consumed diets rich in alpha-linolenic acid, and decreased about 45% when they were on the linoleic acid diet, when compared with the typical American diet.
Compared with the average American diet, the diets high in polyunsaturated fats were also shown to significantly lower the levels of other inflammatory markers involved in atherosclerosis called adhesion molecules.
The two diets high in polyunsaturated fat, such as those found in walnuts, were also shown to have a favorable effect on cholesterol levels, lowering total cholesterol by 11% and lowering “bad” LDL cholesterol by 11%-12%, compared with the average American diet.
“The important new finding with our research is that a diet high in walnuts beneficially affects multiple risk factors for coronary heart disease, which can have a greater impact on decreasing cardiovascular risk than just targeting single risk factors,” author and Penn State nutritionist Penny Kris-Etherton, PhD, says in a press release.
In March 2004, the U.S. Food and Drug Administration said that foods containing walnuts could be labeled as a heart-healthy food. Specifically, the new FDA-approved health claim reads: “Supportive but not conclusive research shows that eating 1.5 ounces of walnuts per day, as part of a low saturated fat and low-cholesterol diet, and not resulting in increased caloric intake may reduce the risk of coronary heart disease. See nutrition information for fat [and calorie] content.”