The researchers suggest that macadamia nuts should be included among nuts with qualified health claims.
"We looked at macadamia nuts because they are not currently included in the health claim for tree nuts, while other tree nuts are currently recommended as part of a heart healthy diet," said Dr. Amy E. Griel, a recent Penn State Ph.D. recipient in nutrition and now senior nutrition scientist at The Hershey Company.
"Macadamia nuts have higher levels of monosaturated fats, like those found in olive oil compared with other tree nuts," she added.
"Epidemiological studies showed that people who are frequent nut consumers have decreased risk of heart disease," said Penny Kris-Etherton, co-author and distinguished professor of nutritional sciences.
The study involved participants who had slightly elevated cholesterol levels, normal blood pressure and were not taking lipid-lowering drugs.
The participants were randomly assigned either the macadamia nut diet or the standard American diet and provided all meals for the participants for five weeks. They then switched diets and continued eating only food provided by the researchers for another five weeks.
The findings revealed that Healthy Heart diet with macadamia nuts did reduce total cholesterol, low-density lipoprotein cholesterol and triglyceride levels compared with the standard American diet.
The macadamia nuts reduced total cholesterol by 9.4% and low-density lipoprotein by 8.9%.
"We found that the reduction in LDL or bad cholesterol we observed was greater than would be predicted by just the healthy fats in the nuts alone," said Griel.
"This indicates that there is something else in the nuts that helps lower cholesterol," she added.
The findings appear in the current issue of the ,i>Journal of Nutrition.
From the April 14, 2008, Prepared Foods e-Flash