Hypertension, vitamin D deficiency, and calcium metabolism

Abstract

Vitamin D deficiency like many other chronic diseases such as diabetes, obesity, and hypertension is increasing in prevalence. Traditionally, vitamin D was thought to be only important for its role in bone and calcium homeostasis. With the improvement of vitamin D assays including utilization of liquid chromatography tandem mass spectrometry (LC-MS/MS), measuring serum levels of 25-hydroxyvitamin D [25(OH)D] has become more reliable. The optimal serum 25(OH)D concentration for skeletal health remains to be debated and is even less certain for extra-skeletal health such as hypertension. The target serum 25(OH)D concentration may differ according to the genetic make-up/pro fi le of each individual, which may consist of different gene polymorphisms in the vitamin D receptor and proteins involved in vitamin D metabolism. Potential mechanisms of vitamin D de fi ciency causing hypertension involve the renin-aldosterone-angiotensin system (RAAS) and endothelial function. As many patients with obesity also have insulin resistance, one could consider insulin resistance as a mediator in causing elevated blood pressure. Based on data from cross-sectional and cohort studies, vitamin D de fi ciency increases the risk of incident hypertension. Although more de fi nitive trials have not yet been completed to examine the role of vitamin D in hypertension, it seems prudent to recommend that patients with vitamin D de fi ciency be encouraged to modify their lifestyles and take vitamin D supplementation to achieve serum 25(OH)D concentrations that are optimal for skeletal health (at least 30 ng/mL). The completion of randomized controlled trials will inform whether vitamin D can in fl uence the onset of hypertension and/or reduce blood pressure in individuals with established hypertension.