A Year‐long Trial to Examine the Effects of a Daily Dose of Walnuts on Cardiometabolic Risk Markers in an Elderly Population

Abstract

Background/ObjectiveLong‐term observational studies and short‐term intervention trials have linked nut consumption with improved cardiometabolic risk factors. However, long‐term trials on nut intake and cardiometabolic risk are lacking. We conducted a year‐long trial to examine the effects of a daily dose of walnuts on cardiometabolic risk markers in an elderly population.MethodsA total of 356 participants (Ages 62–79) were randomly assigned to a walnut or control group. Participants in the walnut group were provided with packaged walnuts (1, 1.5, or 2 oz.) and asked to incorporate into their daily habitual diet. The walnut supplement provided an estimated 15% of their daily energy. Participants in the control group were asked to continue with their habitual diet and to refrain from eating walnuts or excessive intake of other nuts. Both groups were asked to maintain their lifestyles. Blood samples were obtained at baseline and one year and assayed for total cholesterol, LDL and HDL cholesterol, and triglycerides. Blood pressure and waist circumference measurements were obtained at baseline and one year. Data was analyzed using logistic regression and t‐test.ResultsA total of 314 participants completed the study. Data from five participants was incomplete, thus the final sample for this analysis was 309 (155 walnut, 154 control, 66% female). Triglycerides decreased significantly in the walnut group compared to control [−8.41 mg/dl (95% CI −15.54, −1.29 & P=0.02). This was accompanied by a non‐significant decrease in total cholesterol [−3.49 mg/dl (95% CI −9.94, 2.96, & P=0.29), LDL‐cholesterol (−2.40 mg/dl | 95% CI −7.73, 2.93 P=0.38), systolic blood pressure (SBP) (−1.25 mm/Hg | 95% CI −4.96, 2.47 P=0.51), and diastolic blood pressure (−1.62 mm/Hg | 95% CI −3.91, 0.67 & P= 0.17). HDL‐cholesterol increased modestly in the walnut group (+0.35 mg/dl | 95% CI −1.08, 1.78 & P= 0.38). Fasting glucose levels also increased in the walnut group although not significantly (FGL) (+1.82 mg/dl | 95% CI −0.67, 4.32 & P= 0.15). There were no significant between‐group differences in waist circumference.ConclusionSupplementing the diet of older adults with a daily dose of walnuts and no other dietary advice can result in improved blood lipids and blood pressure without adverse effects on waist circumference.Support or Funding InformationThe study is funded by the California Walnut Commission.