Nuts about Nutrition

Prepared Foods, March, 2001 by Fran Labell

Recent studies support the health benefits of nuts, making them an ingredient option for more nutritious foods.

There's more good news about nuts. Eating a small portion of nuts several times a week actually benefits one's health.

Due to their high fat content, nuts traditionally have been viewed as an indulgent food. They're commonly used in confections, ice cream, snacks and baked goods, but also have found a place in entrees, salads and side dishes. With more research coming out supporting nuts' health benefits, formulators may consider using them in functional foods.

Studies support the idea that nuts should become a regular part of a healthy diet. They offer protein, fiber, vitamin E, folate, and many vitamins and minerals. They also derive a high percentage of their calories from fat, but it is polyunsaturated and monounsaturated fat.

The International Tree Nut Council sponsored a recent conference called "Making the Claim for Nuts" at the Georgetown University Center for Food and Nutrition Policy. Summaries of some of the presentations highlight the latest research on nut nutrition.

Cardiovascular Health

Both epidemiological and clinical studies indicate that eating nuts benefits cardiovascular health. Gary Fraser, professor of epidemiology, Loma Linda University, has conducted several dietary studies of more than 34,000 Seventh Day Adventists living in California. The results of a six-year study showed that people who ate five or more servings of nuts per week experienced 50% fewer heart attacks than non-nut eaters did. Subjects consumed the nuts of their choice, which included tree nuts or peanuts. Thirty percent reported eating peanuts. Twelve-year findings with this population yielded similar results.

Dr. Joan Sabate, M.D., Ph.D., professor of nutrition and chairman, Dept. of Nutrition, School of Public Health, Loma Linda University, found that people who ate moderate amounts of walnuts had lower blood cholesterol levels. In his first clinical study, he randomly placed 18 healthy young men on two mixed natural diets. The diets were identical, except that in one, 20% of the calories from fat were derived from walnuts. Those on the walnut diet had reductions of 12.4% in total cholesterol, 16.3% in low density lipoprotein (LDL) cholesterol and 4.9% in high density lipoprotein (HDL) cholesterol. They also exhibited a lowering in the ratio of LDL to HDL.

In another of Sabates studies, 49 men and women with a mean age of 56 years who had polygenic hypercholesterolemia participated in a randomized, crossover feeding trial. The control diet was a Mediterranean diet. The experimental diet was similar in energy and fat content, but walnuts replaced approximately 35% of the energy from fat. The walnut diet produced mean reductions of 4.1% in total cholesterol level, 5.9% in LDL cholesterol and 6.2% in lipoprotein (a).

"We served the whole nut because we were interested in the effect of whole foods served as commonly consumed," explains Sabate. "The main reason for the cholesterol reduction was the nature of the fat. Walnuts are high in polyunsaturated fat that contains alphalinolenic acid, which is a precursor of the omega 3 fatty acids found in fish oil. The decrease in cholesterol was even greater than predicted because of other components that may contribute, like fiber protein."

In a study involving peanuts and peanut products, Penny Kris-Etherton, professor of nutrition, Pennsylvania State University, showed that eating a diet that includes polyunsaturated and monounsaturated fat can be heart-healthy. Her group performed a randomized, double-blind crossover study to look at the cardiovascular disease risk of five different diets. These included the Average American Diet, the American Heart Association Step II lowfat diet and three diets high in monounsaturated fatty acids (MUFA). The high MUFA diets contained 34-36% fat and relied on olive oil, peanut oil or peanuts and peanut butter.

Results showed that the three high MUFA diets lowered total cholesterol 10% and LDL cholesterol 14% without lowering HDL cholesterol. The Step II lowfat diet lowered total cholesterol and LDL cholesterol by comparable amounts, but it also reduced HDL cholesterol. The Step II diet raised triacylglycerol concentrations--a risk factor for cardiovascular disease--while the high MUFA diets lowered it.

Wanda Morgan, Ph.D., associate professor of human nutrition and food science at New Mexico State University, asked test subjects on self-selected diets to supplement their diets with 68 g of pecans every day. The control group refrained from eating nuts. The pecan eaters lowered their LDL cholesterol by 6% at the end of eight weeks. This was in spite of the fact that the pecan eaters ate more fat each day than the control subjects.

Cancer Prevention

Almonds showed promise in preventing colon cancer in a study conducted by Paul Davis, associate research nutritionist, Department of Nutrition, College of Agriculture and Environmental Science, University of California-Davis.