Like macadamias? You can keep eating them
The nut, often ignored in nutrition guidelines, is found to have high levels of healthy fats
Penn State researchers have discovered what University of Hawaii scientists have known for many years: Macadamia nuts are good for you.
A heart-healthy diet with macadamia nuts reduced total cholesterol, low-density lipoprotein cholesterol and triglyceride levels compared with the standard American diet, Penn State researchers have reported.
In an online story titled "Hawaiian Treasure, Macadamia Nuts Good for the Heart," nutritional scientist Amy Griel said researchers looked at macadamia nuts because they are not among tree nuts recommended as part of a healthy diet.
However, she said, "Macadamia nuts have higher levels of monounsaturated fats, like those found in olive oil, compared with other tree nuts."
The Penn State study was supported by the Hershey Co. and the National Institutes of Health. In December 2004, Hershey bought Mauna Loa Macadamia Nut Corp., which has the rights to buy all the nuts of ML Macadamia Orchards LP, the state's largest nut grower.
The study involved two diets, a Heart Healthy diet with macadamia nuts and a standard American diet.
Dr. David Curb, UH professor and Pacific Research Institute president/chief executive officer and medical director, said results of the Penn State study appear similar to a UH study reported in 2000.
There are so many variables in diet studies that "it's good to have studies which confirm results," he said in an interview. He noted that one of the Penn State researchers, Penny M. Kris-Etherton, is a nationally known professor of nutrition.
Curb, who was lead researcher for the UH study, said, "Nuts in general have gotten a lot of attention in the last few years. When we started the macadamia study, it wasn't so clear that nuts were a healthy food."
However, he said, the UH study showed "if you substitute them for the trans fats you eat, they're really good for you. Where you get into trouble is people will eat them in addition to the standard American diet. So what we were basically doing was substituting macadamia nuts for fats."
Curb and his researchers evaluated 30 participants on three different diets for 30-day cycles each. They found a macadamia nut-based diet was superior to a low-fat diet in reducing cholesterol, he said.
There was also a question when the study began whether people could tolerate the amount of fat from mac nuts, Curb said.
The first UH study looked at that issue and "really didn't find they were a problem," he said. One person who had been eating 50 percent of calories as mac nuts had some stomach problems, he said. "But that is not unusual, for people to be intolerant of fat."
The Penn State diets each contained 33 percent calories from total fat. The Heart Healthy diet with mac nuts had 7 percent saturated fat, 18 percent monounsaturated fat and 5 percent polyunsaturated fat.
Macadamia nuts were substituted for other sources of fat and protein in the diet, Griel said.
The standard American diet had 13 percent saturated fat, 11 percent monounsaturated fat and 5 percent polyunsaturated fat.
"Now, studies are showing chocolate is good for you, especially dark chocolate," Curb said, suggesting a new study of chocolate-covered mac nuts might be warranted.