Nutrition Comes Out of Its Shell

Peanuts seem so commonplace, we often lose sight of how complex and amazing they are. They originated in South America as early as 3000 BC and have become a staple in cuisines all over the world.

They are, of course, not nuts at all, but legumes that grow underground. When harvested, both the shell and the kernel are quite soft. Then they are dried and roasted or processed in other ways to provide the more than 6 pounds of peanuts and peanut products that the average American consumes each year.

The recent scientific news about peanuts and nuts has served to reinforce the wisdom of our ancestors who intuitively incorporated them into their diets.

Hunger suppression

One of the major obstacles to weight loss is a feeling of being hungry; most pharmaceutical weight-loss approaches have been directed at appetite suppression.

In a study at Purdue University, subjects who were fed snacks of peanuts and peanut butter found their hunger reduced for 21/2 hours, compared with only an hour when they were fed other snacks, such as rice cakes and pickles. This shouldn't surprise anyone, because the difference in calories and fat content of the snacks is dramatic. The important news, however, is that eating foods such as peanuts--which were once thought to be too high in fat and calories for a healthy diet--can actually reduce the overall number of calories consumed and improve the profile of dietary fat intake by increasing the proportion of mono-and polyunsaturated fats.

Cholesterol-lowering

We have known for a long time that substituting poly-and mono-unsaturated fats for the high-saturated-fat diet consumed by many Americans can lower levels of total and low-density lipoprotein cholesterol (or LDL, the so-called bad cholesterol) and decrease the risk of cardiovascular disease. Researchers at Penn State University found that a diet including two to three servings of peanuts and peanut butter per day lowered LDL and total cholesterol more than just eating a lowfat diet.

Results from the Nurses Health Study at Harvard University (86,000 women followed for almost 20 years) showed that women who routinely ate more than five servings of peanuts and nuts per week decreased their risk of heart disease by about one-third.

Weight control

In another study from Harvard, two groups of people were put on weight-loss diets. The first group consumed a standard low-fat diet (20% of the calories from fat), and a similar group consumed a diet that contained 35% of the calories as fat (moderate fat intake), most of which came from mono-and polyunsaturated fats. Both diets had the same number of calories. Both groups initially lost the same amount of weight, but the group on the moderate-fat-intake diet managed to keep that weight off for the two years they were followed; the low-fat group did not.

Cancer prevention

Phytosterols are natural chemicals found in plants. They are the plant equivalent of cholesterol, which is produced by animals. One of the most common phytosterols is a substance known as beta-sitosterol, which is thought to offer protection from colon, prostate and breast cancers by a number of means, including inhibition of cell division, causing the death of tumor cells and modifying hormones needed for tumor growth.

Researchers at the State University of New York at Buffalo have identified these compounds in high concentrations in some plant oils and seeds--and in peanuts and peanut products.

These same phytosterols are also known to play a role in preventing heart disease by interfering with cholesterol absorption in the intestine.

Some special products are now on the market that contain enough of these compounds to actually lower blood cholesterol by 10% to 15%.

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Dr. Sheldon Margen is a professor of public health at UC Berkeley; Dale A. Ogar is managing editor of the UC Berkeley Wellness Letter. Send questions to Dale Ogar, School of Public Health, UC Berkeley, Berkeley, CA 94720-7360, or e-mail to daogar@uclink4.berkeley.edu. Eating Smart appears the second and fourth Mondays of the month.

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