Sunshine vitamin linked to fewer heart events: Meta-analysis

Higher blood levels of vitamin D are associated with significantly fewer cardiovascular disease (CVD) events and a lower risk of mortality from CVD, says a new meta-analysis.

Analysis of data from 180,667 participants revealed that for every 10-ng/mL increase in blood levels of vitamin D, the risk of CVD events decreased by 10%, while the risk of dying from cardiovascular disease decreased by 12%.

“The present meta-analysis showed that higher serum 25(OH)D concentrations had a protective effect on total CVD events and CVD mortality,” wrote scientists from Capital Medical University (Beijing), the China National Clinical Research Center for Neurological Diseases (Beijing), the Beijing Institute for Brain Disorders, the Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease, and Pennsylvania State University in the American Journal of Clinical Nutrition.

Details about D

Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. Both D3 and D2 precursors are transformed in the liver and kidneys into 25(OH)D, the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D).

Vitamin D deficiency in adults is reported to precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases. There is also some evidence that the vitamin may reduce the incidence of several types of cancer and type-1 and -2 diabetes.

While our bodies do manufacture vitamin D on exposure to sunshine, the levels in some northern countries are so weak during the winter months that our body makes no vitamin D at all, meaning that dietary supplements and fortified foods are seen by many as the best way to boost intakes of vitamin D.

Meta-analysis details

The researchers pooled data from over 180,000 people from general populations, which provided 9,170 CVD deaths, 7,074 cases of ischemic heart disease or myocardial infarction, 3,127 stroke cases, and 3,037 cases of heart failure.

Crunching the numbers revealed a non-linear (J-shaped) association for CVD events and CVD deaths.

The researchers noted that it is not currently known exactly how vitamin D may impact CVD, but data from other studies indicated several potential mechanisms of action: “[E]xperimental studies have indicated a regulatory effect of vitamin D on cardiomyocytes and vascular smooth muscle cells,” they wrote. “In addition, decreased serum 25(OH)D will activate the renin angiotensin system, consequently increasing blood pressure. Furthermore, it was reported that vitamin D has anti-inflammatory actions, which play an important role in atherogenesis. Vitamin D also inhibits certain matrix metalloproteinases (MMPs) that are important in plaque instability and that are known to increase in MI, notably MMP-9 and MMP-2.”

“Well-designed randomized vitamin D therapy trials are needed to confirm the role of vitamin D in preventing overt CVD, as well as to define optimal vitamin D status for a reduction in overall CVD risk,” they concluded.

Source: American Journal of Clinical Nutrition
Published online ahead of print, doi:10.3945/ajcn.116.140392
“Serum 25-hydroxyvitamin D and the risk of cardiovascular disease: dose-response meta-analysis of prospective studies”
Authors: R. Zhang et al.