by Janeen Madan
Between the ever-expanding nut section at your local grocery store to specialty nut stands popping up at farmer’s markets, nuts have become a craze that has spread just about every where. And, for good reason! To get the nutritional scoop on nuts, I spoke with Dr. Diane McKay over at the HNRCA’s Antioxidant Research Laboratory.
Recently, McKay has been researching tree nuts and their health benefits of phytonutrients—chemical compounds in plant foods. In discussing a host of health benefits, she explains that several large observational studies have shown that nuts are associated with lower mortality, as well as reduced risk for cardiovascular diseases and type 2 diabetes. For example, a recent study published in the New England Journal of Medicine in November 2013, found that eating a handful of nuts daily was associated with a 20% lower death rate. But, observational studies do not tell us anything about cause and effect.
“Evidence from randomized clinical trials (RCTs) is limited,” explains McKay. “RCTs conducted to date have examined the cholesterol-lowering properties of nuts in adults with elevated cholesterol levels. In fact, evidence from these studies is sufficient to warrant the following qualified health claim: Scientific evidence suggests, but does not prove, that eating 1.5 ounces per day of most nuts as part of a diet low in saturated fat and cholesterol’ may reduce the risk of heart disease,” says McKay.
What specific nutrients found in nuts contribute to these health-promoting properties? McKay explains that nuts are rich in mono- and polyunsaturated fats, which contribute substantially—but not completely—to their cholesterol-lowering effects. This is even more pronounced when nuts are substituted for unhealthy snacks and foods with a high saturated fat content. Tree nuts are also packed with other heart-healthy nutrients like vitamin E, minerals and fiber, which may also contribute to this effect, she says. The list of health-promoting nutrients does not end there.
Nuts are also a rich source of phytochemicals, particularly polyphenols—the focus of McKay’s current research. She is investigating the contribution of these nut polyphenols to their purported health benefits. “My current study will examine the effects of consuming pecans, which are particularly high in certain polyphenols, on selected biomarkers of heart disease and type 2 diabetes, including inflammation, blood vessel health, glucose control, antioxidant activity, and oxidative stress, in older, overweight adults with excess belly fat.”
Over a four-week period, study participants will receive meals, either with or without pecans. The pecan content of these meals will be the same amount stated in the health claim, ~1.5 oz/2000 kcal/day, McKay explains. And, the meals without pecans will be designed to have the same fiber and fat content as the pecan meals. This will enable the investigators to isolate the effects of the nut polyphenols in participants receiving the pecan meals.
So, it looks like we may have more reason to turn to nuts aside from baking them into an annual pecan pie or waiting until Friday for Cashew Chicken take-out . Eating a serving of nuts—the amount that fits in the palm of your hand, that is—every day, year-round, can be extremely beneficial to health.
Studies like Dr. McKay’s may set the precedent for incorporating nuts into your daily routine. And at Friedman, we’re all on board for some added healthy fat, no matter how you crack it.
Janeen Madan is a first-year FPAN student focused on international nutrition programming. She has realized that she’s not cut out for the Boston winter and is counting down to the spring. To learn more about her, visit our Meet Our Writers page.