A recent study published online in the journal, Nutrients[1], suggests daily tree nut consumption reduces the risk of metabolic syndrome (MetSx) by improving waist circumference, lipid biomarkers, and/or insulin levels, without requiring calorie restriction, in young adults.
In a randomized, parallel arm, dietary intervention study design, researchers at Vanderbilt University Medical Center enrolled 84 men and women, ages 22-36, most of whom were either overweight or obese (BMI 24.5 to 34.9 kg/m2) and had at least one MetSx risk factor at baseline (abdominal obesity, elevated triglycerides, low HDL cholesterol, high blood pressure, or elevated levels of blood glucose). Participants consumed either one ounce of mixed unsalted tree nuts or one ounce of a carbohydrate-rich snack twice daily. Both snacks provided the same number of calories, protein, fiber, and sodium and were part of a 7-day eucaloric weight maintenance menu that repeated throughout the study duration of 16 weeks.
The results showed females who consumed tree nuts snacks had a reduced waist circumference (mean difference: -2.20 ± 0.73 cm, P = 0.004) and a trend toward reduced visceral (intra-abdominal) fat (-5.27 ± 13.05 cm2, P = 0.06) compared to those consuming carbohydrate snacks. Males who consumed tree nuts snacks had decreased blood insulin levels (-1.14 ± 1.41 mIU/L, P = 0.05). Both males and females consuming tree nuts snacks saw an effect on triglycerides and TG/HDL ratios (P = 0.04 for both) with TG/HDL ratios reduced ~11% compared to those consuming carbohydrate snacks.
Heidi J. Silver, R.D., M.S., Ph.D., Research Professor of Medicine at Vanderbilt University Medical Center, "we observed a 67% reduction in MetSx score in females and a 42% reduction in MetSx score in males."
Overall prevalence of MetSx, which increases risk for diabetes and cardiovascular diseases, has increased to 21.3% among healthy American young adults, aged 20-39 years.[2] "We know that snacking contributes almost 25% of total daily calories in young adults in the US," explained Dr. Silver. "Substituting typical high carbohydrate snacks with tree nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts) would likely have a positive impact in reducing the risk of metabolic syndrome and its consequences in this age group."
The International Tree Nut Council Nutrition Research & Education Foundation (INC NREF) is a non-profit, non-governmental organization dedicated to supporting nutrition research and education for consumers and health professionals throughout the world. Members include those associations and organizations that represent the nine tree nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts).
[1] Sumislawski K., Widmer A., Suro R.R., Robles M.E., Lillegard K., Olson D., Koethe J.R., Silver H.J., 2023. Consumption of tree nuts as snacks reduces metabolic syndrome risk in young adults: A randomized trial. Nutrients. 15, 5051. https://doi.org/10.3390/nu15245051
[2] Hirode, G., R.J. Wong, 2020. Trends in the prevalence of metabolic syndrome in the United States, 2011–2016. JAMA 323:2526–2528.
