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Macadamia nuts
cut cholesterol,
study says

Monounsaturated fats,
derived from the nuts,
prove to be healthy

By Mary Adamski
Star-Bulletin

Despite their image as a sinfully rich snack, macadamia nuts lowered the cholesterol level of participants in a University of Hawaii feeding study.

The research results published this week in the American Medical Association's "Archives of Internal Medicine" indicated that "the consumption of a diet high in monounsaturated fats, a significant portion of which were derived from macadamia nuts, appears to lower serum cholesterol levels when total energy balance and percentage of energy from fat are maintained."

Dr. David Curb, lead researcher in the feeding study, said macadamia nuts "had an olive oil effect ... would act to lower your cholesterol." Other studies have revealed that olive oil, also a monounsaturated fat source, has beneficial effects in the body's cholesterol production.

Curb and his associates put 30 study participants through three different diets for a 30-day cycle each. The first was a typical American diet, high in saturated fat from meat and dairy products, in which 37 percent of the calories were from fat.

A macadamia nut-based diet also provided 37 percent of calories from fat.

Under a third regimen, participants followed the American Heart Association Step 1 plan, a low-fat diet stressing vegetables and cereals, with 30 percent of calories from fat.

"Each person was their own control subject. We could compare the subjects to themselves. It's a state-of-the-art way to do a diet study," said Curb, principal investigator in the Honolulu Heart Program, a 30-year-old research project. He said the macadamia research was the "first rigorous, controlled feeding study ever done in Hawaii."

This portion of the research, funded by a grant from the U.S. Army Medical Research Acquisition Activity in Maryland, cost about $500,000 and was completed about four years ago. The research continued into longer term effects of a diet with monounsaturated fat from macadamia nuts.

"We're not advocating that people go out and go on nut diets," Curb said. "We have show these can be part of a healthy diet, that there's no need to avoid nuts. In fact they can be good for you.

"There's nothing magic about the macadamia nut, the profile is similar for tree nuts in general. All have low levels of the saturated fats. None of the tree nuts would raise cholesterol if eaten in moderate amounts."

Chefs from island restaurants and hotels prepared tasty foods for the diet participants at a study kitchen at Kapiolani Community College.

Everyone had to eat all their meals for the three-month duration at the college culinary arts program dining facility, and they had to clean their plates.

"It wasn't like eating a can of nuts, it would be a meal like you'd have in a restaurant," said the research chief.

The cooks had to weigh exact portions to fit the individuals, who ranged from 18 to 53 years old and had different daily calorie requirements, because "we couldn't have them gaining or losing weight."

The baseline value used for the study was a mean total cholesterol level of 250, which indicates 250 milligrams per deciliter of cholesterol which is a fatty substance necessary for manufacturing cells. The baseline for low-density lipoprotein (bad cholesterol) was 134 and for triglyceride high-density lipoprotein (good cholesterol) 55.

After the 30-day diet, the mean total level for subjects on the American diet was 201, and 130 LDL and 55 HDL.

For participants on the American Heart Association diet, the readings were 193 total cholesterol, 124 LDL and 52 HDL.

For people on the macadamia nut diet, the mean total level was 191 milligrams per deciliter, 124 LDL and 53 HDL.