Lead researcher Karen Jaceldo-Siegl of Loma Linda University and colleagues studied the association between tree nuts -- almonds, Brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts -- and metabolic syndrome, a cluster of risk factors with a twofold increased risk for cardiovascular disease, and a fivefold increased risk for type 2 diabetes.
The presence of any three of the five following conditions results in a diagnosis of metabolic syndrome: abdominal obesity; elevated triglycerides; low high-density lipoprotein cholesterol, or the good cholesterol; high blood pressure and hyperglycemia, or high blood sugar levels. It estimated about a third of the U.S. population has metabolic syndrome.
The researchers at Loma Linda University studied 803 Seventh-day Adventist adults using a validated food frequency questionnaire and assessed both tree nut and peanut intake together and separately. Mean tree nut intake was 16 grams/day, or a half ounce, among the high tree nut consumers and 5 grams/day, or quarter ounce, among low tree nut consumers.
The study, published in the online journal PLoS One, found one serving, or 1 ounce, of tree nuts per week was significantly associated with 7 percent less risk of less metabolic syndrome.
"Interestingly, while overall nut consumption was associated with lower prevalence of metabolic syndrome, tree nuts specifically appear to provide beneficial effects on metabolic syndrome, independent of demographic, lifestyle and other dietary factors," Jaceldo-Siegl said in a statement.
In addition to the effect of nuts on metabolic syndrome the researchers also looked at the effect on obesity.
"We found that high tree nut consumers had significantly lower prevalence of obesity compared to the low tree nut consumers," Jaceldo-Siegl said. "And, high consumers of tree nuts had the lowest prevalence of obesity when compared to the low peanut/tree nut groups."
The International Tree Nut Council funded the study. The international, non-profit, non-governmental organization is dedicated to supporting nutrition research and education for consumers and health professionals throughout the world.
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