Monday, April 22, 2013
New findings on tree nuts and health
Three new studies involving tree nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts) were presented this week at the Experimental Biology Meeting in Boston, MA. Tree nut consumption was associated with a better nutrient profile and diet quality; lower body weight and lower prevalence of metabolic syndrome; and a decrease in several cardiovascular risk factors compared to those seen among non-consumers.
First, the Adventist Health Study looked at the effect of nut intake on the risk of metabolic syndrome (MetS) in a population with a wide range of nut intake ranging from never to daily. Researchers at Loma Linda University studied 803 adults using a validated food frequency questionnaire and assessed both tree nut and peanut intake together and separately. "Our results showed that one serving (28g or 1 ounce) of tree nuts per week was significantly associated with 7% less MetS," stated lead researcher Karen Jaceldo-Siegl, DrPH. "Interestingly, while overall nut consumption was associated with lower prevalence of MetS, tree nuts specifically appear to provide beneficial effects on MetS, independent of demographic, lifestyle and other dietary factors."
The second study looked at 14,386 adults participating in the 2005-2010 National Health and Nutrition Examination Surveys (NHANES). Intake was from 24-hour recall data and tree nut consumers were defined as those who consumed more than ¼ ounce of tree nuts (average consumption was about an ounce/day). As seen in previous research, tree nut consumers had higher daily intakes of calories (2468 v 2127 calories) and nutrients of concern: fiber (21v 16 grams [g]); potassium (3028 v 2691 milligrams [mg]); magnesium (408 v 292 mg); monounsaturated fats (36 v 29 g), and polyunsaturated fatty acids (21 v 17 g), but lower intakes of added sugars (15 v 18 teaspoons), saturated fats (25 v 27g), and sodium (3197 v 3570 mg) than non-consumers. Tree nut consumers also had lower weight (80 v 82 kg; p=0.0049), BMI (28v 29; p<0.0001), and waist circumference (96 v 98 cm; p=0.0006) than non-consumers. In addition, those who consumed tree nuts had lower systolic blood pressure (120 v 122 mmHg; p=0.0120) and higher HDL-cholesterol (the good kind) (55 v 53 mg/dL; p=0.0020). On a population basis, these reduced risk factors could lead to better health. "Consumption of tree nuts should be encouraged to improve diet quality, nutrient intake, weight status, and some cardiovascular risk factors," according to Carol O'Neil, PhD, MPH, RD, lead author on the paper and Professor at Louisiana State University Agricultural Center.
Finally, a third study looked at several markers for cardiovascular disease risk. In 2011, researchers from the University of Toronto and St. Michael's Hospital in Toronto, Canada, published the largest study to date on nuts and diabetes (Jenkins, D.J.A., et al., 2011. Nuts as a replacement for carbohydrates in the diabetic diet. Diabetes Care. 34(8):1706-11.), showing that approximately two ounces of nuts a day, as a replacement for carbohydrate foods, can improve glycemic control and blood lipids in those with type 2 diabetes. The researchers looked at the effects of nuts on various cardiovascular markers. "We found that nut consumption was associated with an increase in monounsaturated fatty acids (the good fats) in the blood, which was correlated with a decrease in total cholesterol, LDL cholesterol (the bad kind), blood pressure, 10-year coronary heart disease risk, HbA1c (a marker of blood sugar control over the previous three months) and fasting blood glucose," explained Cyril Kendall, Ph.D., of the University of Toronto. "Nut consumption was also found to increase LDL particle size, which is less damaging when it comes to heart disease risk." According to Dr. Kendall, this study found additional ways in which nut consumption may improve overall cardiovascular health.
"These three new studies, independent of one another, support the growing body of evidence showing that consuming nuts can improve your health," states Maureen Ternus, M.S., R.D., Executive Director of the International Tree Nut Council Nutrition Research & Education Foundation (INC NREF). "In 2003, FDA (in its qualified health claim for nuts and heart disease) recommended that people eat 1.5 ounces of nuts per day—well above current consumption levels—so we need to encourage people to grab a handful of nuts every day."