Lancet review: Vitamin D marker for deteriorating health

PHILADELPHIA — A review published in the Lancet Diabetes & Endrocrinology last week determined that low vitamin D levels are not a cause but a consequence of ill health. 

"If the health benefits of high vitamin D concentrations shown by data from observational studies are not reproduced in randomized trials … then the relation between vitamin D status and disorders are probably the result of confounding or physiological events involved in these disorders," stated lead author Professor Philippe Autier from the International Prevention Research Institute in Lyon, France.

They found that the benefits of high vitamin D concentrations from observational studies — including reduced risk of cardiovascular events (up to 58%), diabetes (up to 38%), and colorectal cancer (up to 34%) — were not confirmed in randomized trials. According to Autier, "What this discrepancy suggests is that decreases in vitamin D levels are a marker of deteriorating health. Ageing and inflammatory processes involved in disease occurrence and clinical course reduce vitamin D concentrations, which would explain why vitamin D deficiency is reported in a wide range of disorders."

"This systematic review is important because it addresses the fact that when people get seriously ill, they often experience nutrient depletions, including low vitamin D levels," Duffy MacKay, VP scientific and regulatory affairs for the Council for Responsible Nutrition said. "When this happens, dietary supplementation should be discussed by the patient and a team of healthcare practitioners because vitamin D is not easily obtained through food, and getting it through sunlight can pose risks—making supplementation a viable option," he said. 

"It may be unrealistic to expect vitamin D in isolation from other healthy habits to prevent a disease such as cancer or cardiovascular disease," MacKay noted. "But we know that one component of disease prevention involves a healthy diet, of which vitamin D is a vital part.”

Autier and colleagues analyzed data from 290 prospective observational studies and 172 randomized trials examining the effects of vitamin D levels on non-bone health outcomes up to December 2012.