Vitamin D & High Blood Pressure
The antihypertensive actions of vitamin D are thought to be the result of suppression of the renin–angiotensin–aldosterone system,[51–53] direct effects on vascular cells,[54,55] effects on calcium metabolism[56] and the prevention of secondary hyperparathyroidism.[57–59] The VDR-knockout mouse develops hypertension.[51]
There have been few studies in children that have evaluated the association between 25(OH)D levels and blood pressure. Smotkin-Tangorra et al. evaluated 25(OH)D levels in 217 obese children and found higher systolic blood pressure in those with levels below 20 ng/ml.[10] This study had only obese children and it is possible that obesity could be a potential confounding factor in determining the effects of low 25(OH)D levels on hypertension. Reis et al. performed a cross-sectional analysis of 3577 adolescents who participated in the 2001–2004 NHANES.[60] They found an adjusted odds ratio of 2.36 (1.33–4.19) for those in the lowest (<15 ng/ml) compared with the highest quartile (>26 ng/ml) of 25(OH)D for hypertension. Our analysis of data from children and adolescents aged 1–21 years using the NHANES 2001–2004 database found significantly higher prevalence of hypertension and higher systolic and diastolic blood pressures in the vitamin D-deficient (<15 ng/ml) group. 25(OH)D deficiency was associated with higher systolic blood pressure (OR: 2.24 mmHg [0.98–3.50mmHg]). Hypertension was 2.5-times more likely in the vitamin D-deficient (<15 ng/ml) group when compared with those with levels above 30 ng/ml.[15]
All the above pediatric studies are cross-sectional analyses, hence they only highlight associations and do not prove causality. Randomized, controlled trials of vitamin D supplementation and its long-term effects on blood pressure in children need to be undertaken to evaluate the effects of vitamin D on blood pressure.
Pediatr Health. 2010;4(1):89-97. © 2010 Future Medicine Ltd.
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