Dietary vitamin D and risk of non-Hodgkin lymphoma: the multiethnic cohort.

The present study explored the association between dietary vitamin D and non-Hodgkin's lymphoma (NHL) risk. The multiethnic cohort (MEC) includes more than 215 000 Caucasians, African Americans, Native Hawaiians, Japanese Americans and Latinos, aged 45-75. After 10 years of follow-up, 939 incident NHL cases were identified. Risk was estimated using proportional hazards' models adjusted for possible confounders. Vitamin D intake was not associated with NHL risk in the entire cohort (P(trend) = 0.72 for men and P(trend) = 0.83 for women), but significantly lowered disease risk in African American women (hazard ratio (HR) = 0.50, 95 % CI: 0.28, 0.90, P(trend) = 0.03) and was borderline protective in African American men (HR = 0.68; 95 % CI: 0.39, 1.19; P(trend) = 0.31) when the highest to the lowest tertile was compared. In NHL subtype analyses, a 19, 36 and 32 % lowered risk, although not significant, was observed for diffuse large B-cell lymphoma, follicular lymphoma and small lymphocytic lymphoma/chronic lymphocytic leukemia in women, respectively. High dietary intake of vitamin D did not show a protective effect against NHL within the MEC except among African Americans, possibly because vitamin D production due to sun exposure is limited in this population.