Much to the chagrin of macadamia nut lovers everywhere, they’ve been on the healthful foods taboo list because of their level of saturated fats, higher than most other tree nuts which are approved by the US Food and Drug Administration (FDA) as healthful foods.

The FDA says nuts that contain more than 4 grams of saturated fat for every 50 grams of nut is too much saturated fat to be considered healthy. The macadamia, Brazil nut, and cashew all fall on the list of nuts to be avoided.

Even with their high concentration of saturated fats, macadamias have a high level of monosaturated fats compared with other tree nuts. It’s the monosaturated fat that makes olive oil such a darling of the health food industry so researchers at Penn State University and the Hershey Company joined forces to see which form of macadamia nut fat had the most bearing on a typical American diet.

The research team, led by Dr. Amy E. Griel, PhD Penn State and senior nutrition scientist for Hershey, enlisted volunteers who ate only the foods provided by the researchers for ten weeks. They all had cholesterol levels slightly above the healthy mark, normal blood pressure readings, and were taking no drugs to lower lipid levels.

For the first five weeks of the study, randomly selected participants ate either a Healthy Heart macadamia nut diet or a standard American diet, both designed to provide the exact number of calories each study participant would need to maintain weight, with no gains or losses, during the study period. After five weeks, each participant’s diet was switched.

The Healthy Heart macadamia nut diet included a daily ration of macadamia nuts - about 1.5 ounces, or about a small handful. The nuts were consumed as snacks, in salads, cookies, and muffins, and as part of meals. The fat content of each diet was the same, 33% of all calories consumed, although the proportions of fats was different, as follows:

Macadamia nut diet vs typical American diet:

• 7% saturated fat vs 13% saturated fat

• 18% monosaturated fat vs 11% monosaturated fat

• 5% polyunsaturated fat vs 5% polyunsaturated fat

To keep fat content the same for each diet, skim milk and 2% milk were substituted accordingly and macadamia nuts were added.

When study participants consumed the Healthy Heart macadamia nut diet, cholesterol levels dropped by about 9.4% and low-density lipoprotein dropped by 8.9%, in keeping with previously conducted epidemiological studies which have shown that people who frequently eat nuts enjoy a decreased risk of developing heart disease.

The full details of this study can be found in the Journal of Nutrition’s current issue. The National Institutes of Health (NIH) and The Hershey Company provided funding for this study. Hershey owns the Mauna Loa Macadamia company.