Nutritional Facts

The Heart-Healthy Walnut

A Handful a Day Reduces Cholesterol

By Darl Larsen, Associate Editor

 

A landmark study published recently in the journal Annals of Internal Medicine suggests that substituting a handful of walnuts for more fatty traditional foods in a Mediterranean diet can make that diet much better for the heart.

 

The study, entitled "Substituting Walnuts for Monounsaturated Fat Improves the Serum Lipid Profile of Hypercholesterolemic Men and Women: A Randomized Crossover Trial," was conducted by teams of researchers from the Hospital Clinic of Barcelona, Spain and Loma Linda University in California. High cholesterol patients ranging in age from 28 to 72 were studied over a twelve week period. During the first six weeks, a Mediterranean diet designed to be cholesterol lowering was followed, then during the second six weeks they followed a diet where walnuts replaced a significant portion of energy received from monounsaturated fat.

 

The Mediterranean diet lowered cholesterol effectively, but the walnut enriched version of that diet was even more effective at reducing cholesterol levels. One clinical researcher noted that walnuts reduced the risk of coronary heart disease by 11 percent overall with serum cholesterol falling 4.1 percent, LDL cholesterol 5.9 percent, and lipoprotein (a) 6.2 percent lower than the unmodified Mediterranean diet.

 

"It's as simple as this: if you eat a handful of walnuts a day, you will lower your blood cholesterol," said Dr. Emilio Rios of the Hospital Clinic of Barcelona, "and therefore lower your cardiovascular risk." Dr. Rios co-directed the study.

 

The effect of walnuts on Western diets might be even greater, as these diets are generally higher in saturated fats than Mediterranean diets.

 

"The Barcelona study breaks new ground," said Dr. Joan Sabate of Loma Linda. "We found in our 1993 Loma Linda study that healthy young men can benefit from eating walnuts. Now we can extend our findings to women as well as men, to older people, and to those with high cholesterol who are already at risk of or showing signs of heart disease," she said. This 1993 study was published in the New England Journal of Medicine.

 

The study also found that inclusion of walnuts in the at-home diet was easy, thus consumers are more likely to realize the benefits.  Walnuts can be consumed with food and meals, such as salads or desserts, or even as snacks. It's as simple as a handful from a bag.

 

The previous, Loma Linda study looked at healthy men who were given a two-month diet regimen of additional walnuts (replacing other fats), with the result of a further 12 percent drop in cholesterol levels beyond the 6 percent reduction realized by adherence to the National Cholesterol Education Program's Step One diet-a diet already recommended by the American Heart Association. This 1993 study built on a previous study conducted on more than 31,000 Seventh-Day Adventists, which showed that eating nuts at least five times a week reduced by half the risk of heart attack as opposed to those who ate nuts less than once a week.

 

For years walnuts have intrigued researchers because of the nut's high level of polyunsaturated fatty acids, and n-3 linolenic acid, which has been shown to act positively in reducing blood cholesterol levels. Walnuts have, in fact, one of the highest ratios of polyunsaturated to saturated fat (7 to-I) of any natural food.

 

The Barcelona study patient group was just about equally divided between men and women. one of few such cholesterol studies to look at effects on both genders. The study was conducted by Emilio Rios, M.D., of Barcelona, and Joan Sabate, M.D., Dr.P.H., of Loma Linda.

 

Pacific Nut Producer/ May 2000

In addition to being a crunchy and delicious snack and traditional holiday food, walnuts are proving to be an important part of a heart-healthy diet. Since walnuts have no cholesterol and are high in polyunsaturated fats, they can be used in a low-fat diet to replace animal protein foods that are high in saturated fat. Research is also showing that a diet rich in plant foods may reduce the risk of cancer, heart disease, and diabetes. For details on current nutritional studies please check out: nuthealth.org and treenuts.org.

 

NEW HEALTH AND NUTRITION STUDIES: Information reported by the California Walnut Commission.

 

*U.C. Davis Study: The research universities are continuing to show a positive relationship between walnuts and cholesterol reduction and heart disease risk.. The latest walnut nutrition study is found in the American Journal of Clinical Nutrition. Dr. Sidika Kasim-Karakas's study is entitled "Effects of walnut consumption on plasma fatty acids and lipoproteins in combined hyperlipidemia." Walnut consumption of as little as 5 ounces of walnuts per week significantly reduced total and LDL cholesterol when compared to high-fat diets and also low-fat diets without walnuts. In addition, it was shown that even though the subjects consumed more calories, they did not gain weight.

 

*Barcelona Study: The study, "Substituting walnuts for monounsaturated fat improves the serum lipid profile of hypercholesterolic men and women" shows serum cholesterol reduction by 4.1% and LDL cholesterol reduced by 5.9. This study was done at the University of Barcelona in Barcelona, Spain and replaced some of the monounsaturated fats with walnuts in a healthy Mediterranean diet. The Annals of Internal Medicine published this study in the April 4, 2000 issue.

 

*Kyushu Study: A similar study in Tokyo, entitled "Walnuts lower serum cholesterol in Japanese men and women", has also shown positive effects on cholesterol reduction. Both this study and the Barcelona study were based on the Loma Linda study from 1993 in which it was found that walnuts may help to lower LDL cholesterol by as much as 16% over the AHA recommended Step One diet. The Kyushu University study was published in the February 2000 issue of the Journal of Nutrition. *Please note: to see the reprints of the above articles, search for walnuts at the prompts.

 

WALNUT COMPOSITION: A complete analysis of the chemical composition of walnuts.