Low dietary vitamin D intake was associated with a higher incidence of all stroke and thromboembolic stroke later in life among Japanese-American men, according to results of a long-term study published in Stroke.
Researchers found no significant association between dietary vitamin D intake and hemorrhagic stroke.
The study included 7,385 men from the Honolulu Heart Program, a prospective population-based cohort study of more than 8,000 Japanese-American men who were free of prevalent stroke. The men were aged 45 to 68 years at baseline examination in 1965 to 1968 and were followed through 1999. Dietary vitamin D intake was calculated using the Nutritionist IV Version 3 software from 24-hour dietary recall. Participants were analyzed in quartiles of dietary vitamin D intake.
During the 34 years of follow-up, 960 men developed stroke, with 651 (68%) thromboembolic, 269 (28%) hemorrhagic and 40 (4%) unknown type. Rates of incident stroke adjusted for age were significantly higher among men in the lowest dietary vitamin D quartile compared with the highest (all stroke: 6.38 vs. 5.14 per 1,000 person-years of follow-up, P=.03; thromboembolic stroke: 4.36 vs. 3.3 per 1,000 person-years of follow-up, P=.033). Incident stroke risk adjusted for age, total kilocalories, BMI, hypertension, diabetes, pack-years of smoking, physical activity index, serum cholesterol and alcohol intake was also significantly increased in those in the lowest quartile (all stroke HR=1.22; 95% CI, 1.01-1.47; thromboembolic stroke HR=1.27; 95% CI, 1.01-1.59).
“Our study confirms that eating foods rich in vitamin D might be beneficial for stroke prevention,” said study researcher Gotaro Kojima, MD, a geriatric medicine fellow at the John A. Burns School of Medicine at the University of Hawaii in Honolulu.
The researchers said it is unclear whether these data could be applied to different ethnic groups or to women.
Disclosure: The National Heart, Lung, and Blood Institute and the National Institute on Aging funded this study. The researchers report no relevant financial disclosures.