Scientific Study

BACKGROUND: Dietary interventions and cohort studies relating tree nut consumption to blood glucose levels suggest a possible effect of walnuts. OBJECTIVE: To examine the associations between walnut consumption and diabetes risk using data from the National Health and Nutrition Examination Survey (NHANES).METHODS: NHANES survey data on adults conducting 24 hour dietary recall was pooled across the years 1999 through 2014. Diabetes status or risk was based on self-report, medication use, fasting plasma (FPG) glucose levels and hemoglobin A1c (HbA1c) levels. Individuals were characterized based on reported consumption of walnuts, mixed-nuts, or no nuts. RESULTS: After adjustment for covariates, walnut consumers showed lower risk for diabetes compared to non-nut consumers based on self-report (odds ratio of 0.47 95% confidence interval 0.31-0.72) as well as fasting blood glucose (RRR 0.32 CI 0.17-0.58) and HbA1c (RRR 0.51 CI 0.27-0.99). For each standard deviation of increase in walnut intake, prevalence of diabetes dropped 47%. The gender by walnut interaction suggests the effect may be more potent among women than men (dose response p=0.061). CONCLUSIONS: Both among individuals with known diabetes and those diagnosed based on elevated diabetes blood markers, the prevalence of individuals with diabetes was significantly lower among the walnut consumers. A possible gender specific effect invites further attention.