(HealthDay News) – In Japanese-American men, low dietary vitamin D intake is associated with an increased risk of all stroke and thromboembolic stroke during a 34-year follow-up period.

Gotaro Kojima, MD, from the University of Hawaii in Honolulu, and colleagues investigated the correlation between dietary vitamin D intake and incident stroke risk in 7,385 Japanese-American men from the Honolulu Heart Program. Participants were 45–68 years old at baseline (1965–1968) and were followed through 1999. The Nutritionist IV Version 3 software was used to assess dietary vitamin D intake.

The researchers found that, during 34 years of follow-up, 960 participants developed stroke. Compared with men in the highest dietary vitamin D quartile, those in the lowest quartile had a significantly increased age-adjusted rate of incident stroke (all stroke, 6.38 vs. 5.14 per 1,000 person-years follow-up; thromboembolic stroke, 4.36 vs. 3.3). The significantly increased risk of incident stroke persisted after adjustment for multiple confounding variables for those in the lowest versus the highest quartile of vitamin D (all stroke hazard ratio, 1.22; thromboembolic stroke hazard ratio, 1.27). Dietary vitamin D was not significantly associated with the risk of hemorrhagic stroke.

“Our study confirmed that low dietary vitamin D intake was associated with increased risk of stroke,” the authors write. “Higher vitamin D intake or vitamin D supplementation may be beneficial for stroke prevention. Large prospective placebo-controlled randomized studies are needed to confirm this relationship.”

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