Can Walnuts Reduce Diabetes Risk? If So, in Whom?

Background: In the US, the incidence of diabetes among Hispanics (9.6/1000) and African Americans (9.0/1000) is 38–48% greater than among European Americans (6.5/1000). Higher risk and different lifestyles suggest the need for targeted strategies by ethnic group. Studies have shown walnut consumption associated with reducing risk of diabetes, however, comparisons among ethnic groups have not been conducted. Objective: To compare the associations between walnut consumption and biomarkers of diabetes risk among Hispanics, African Americans, and European Americans, we employed data from the National Health and Nutrition Examination Survey (NHANES). Methods: NHANES survey data for the years from 1998–1994 and again from 1999–2012 was stratified into 3 ethnic groups and diabetes risk was analyzed using the definition of undiagnosed diabetes as being FPG ≥126 mg/dL or A1C ≥6.5% (48 mmol/mol) and no diabetes risk as FPG <100 and HbA1c <5.7. Results: Walnut consumers showed lower risk for diabetes compared with non-nut consumers based on an analysis of biomarkers. HbA1c was lower across all walnut consumers, and the difference between consumers and non-consumers were greatest among Hispanics and 50% greater among African Americans than European Americans. Similarly, fasting blood glucose concentrations were lower among walnut consumers and the effect was twice as great in African Americans and Hispanics as compared with European Americans. Conclusion: Our analysis using NHANES suggests that the effect of walnut consumption on diabetes risk factors is greater in Hispanic and African American groups than European Americans, illustrating a need for ethnic-specific analyses to tailor dietary recommendations to those with the greatest need for reducing diabetes risk.