"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," says 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."
Along with Brazil nuts and cashews, macadamia nuts are not included in the U.S. Food and Drug Administration's list of nuts with qualified health claims because the cut-off point is 4 grams of saturated fat per 50 grams of nuts. Macadamia nuts have 6 grams of saturated fat per 50 grams, cashew nuts have 4.6 grams and Brazil nuts have 7.6 grams of saturated fat per 50 grams of nuts.
"Epidemiological studies showed that people who are frequent nut consumers have decreased risk of heart disease," says Penny Kris-Etherton, co-author and distinguished professor of nutritional sciences.
The researchers used a controlled feeding study to compare a heart-healthy diet with 1.5 ounces – a small handful – of macadamia nuts to a standard American diet. The participants had slightly elevated cholesterol levels, normal blood pressure and were not taking lipid-lowering drugs. Researchers randomly assigned participants to either the macadamia nut diet or the standard American diet and provided all meals for the participants for five weeks. The participants then switched diets and continued eating only food provided by the researchers for another five weeks.
The Healthy Heart diet with macadamia nuts did reduce total cholesterol, low-density lipoprotein cholesterol and triglyceride levels compared with the standard American diet. The researchers reported in the current issue of the Journal of Nutrition, that the macadamia nuts reduced total cholesterol by 9.4 percent and low-density lipoprotein by 8.9 percent.
Individual calorie levels were used for each participant so that they did not gain or lose weight during the study. Both diets were matched for total fat, containing 33 percent calories from total fat. The Heart Healthy diet with macadamia nuts had 7 percent saturated fat, 18 percent monosaturated fat and 5 percent polyunsaturated fat. The standard American diet had 13 percent saturated fat, 11 percent monosaturated fat and 5 percent saturated fat.
"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," says Griel. "This indicates that there is something else in the nuts that helps lower cholesterol."
The macadamia nut diet included macadamia nuts as a snack, mixed into meals, as a salad topping and in cookies and muffins. The total fat was the same in both diets. Macadamia nuts were substituted for other sources of fat and protein in the diet. Switching skim milk for 2 percent milk and adding some macadamia nuts kept fat levels even.
"I think the bottom line is that Macadamia nuts probably should be included in the list of nuts to have a qualified health claim," says Kris-Etherton.
A'ndrea Elyse Messer | EurekAlert!
How cancer metastasis happens: Researchers reveal a key mechanism
19.01.2018 | Weill Cornell Medicine
Researchers identify new way to unmask melanoma cells to the immune system
17.01.2018 | Duke University Medical Center
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
19.01.2018 | Materials Sciences
19.01.2018 | Health and Medicine
19.01.2018 | Physics and Astronomy