To investigate the role of vitamin D in explaining ethnic differences in blood pressure among three ethnic groups in the Netherlands (ethnic Dutch, African Surinamese, and south Asian Surinamese).
Data were derived from the 'Surinamese in the Netherlands: study on ethnicity and health' study, a population-based observational study. We included 1420 participants (505 ethnic Dutch, 330 south Asian Surinamese, and 585 African Surinamese), aged 35-60 years, in whom serum vitamin D (25-hydroxyvitamin D) and SBP and DBP were measured. Data were analyzed by using linear (SBP, DBP) and logistic (hypertension) regression analyses, using ethnicity as independent variable and adjusting for potential confounders. To study the impact of vitamin D, we additionally adjusted for vitamin D in a final model.
South Asian Surinamese had a 5.6 mmHg higher SBP and 4.9 mmHg higher DBP as compared with the Dutch after adjustment for age, sex, season, physical activity, smoking, education, and BMI. Further adjustment for vitamin D explained 14 and 6% of these SBP and DBP differences, respectively. African Surinamese had an 8.9 mmHg higher SBP and 6.8 mmHg higher DBP as compared with the Dutch. Variation in vitamin D explained 7 and 4% of these SBP and DBP differences. South Asian Surinamese and African Surinamese had 2.2 (1.5-3.2) and 3.3 (2.4-4.6) times higher odds of having hypertension compared with ethnic Dutch. Vitamin D explained 25 and 17% of the variations in SBP and DBP, respectively, resulting in odds ratio of 1.9 (1.3-2.9) and 2.9 (2.0-4.3), respectively.
Higher blood pressures and higher hypertension risk in south Asian Surinamese and African Surinamese were partly explained by their poorer vitamin D status. However, even after adjustment, significant ethnic blood pressure differences persisted.