Four common gene variants linked with blood levels of vitamin D and with an increased risk of vitamin D deficiency have been identified by scientists.
An international research consortium-SUNLIGHT- involving investigators from six countries, have made the above discovery.
"We identified four common variants that contributed to the risk for vitamin D deficiency. Individuals inheriting several of these risk-associated variants had more than twice the risk of vitamin D deficiency as was seen in those without these variants," Lancet quoted Dr. Thomas Wang, of the Massachusetts General Hospital (MGH) Heart Center, a co-corresponding author of the study, as saying.
Naturally produced in the skin in response to sunlight, Vitamin D has been added to many types of food and is available in dietary supplements.
However, studies have shown that from one third to one half of healthy adults in developed countries have low levels of vitamin D.
While reduced sun exposure is clearly associated with lower vitamin D levels, environmental and cultural factors - including dietary intake - cannot completely account for variations in vitamin levels.
The fact that vitamin D status tends to cluster in families suggests a genetic contribution.
The SUNLIGHT (Study of Underlying Genetic Determinants of Vitamin D and Highly Related Traits) Consortium involved a research team from the U.S., U.K., Canada, Netherlands, Sweden and Finland who pooled data from 15 epidemiologic studies of almost 32,000 white individuals of European descent.
Results of the comprehensive genetic screening were correlated with participants' serum vitamin D levels.
Statistically significant associations were found for four common variants, all in genes coding enzymes involved with the synthesis, breakdown or transport of vitamin D.
The risk association was independent of geographic or other environmental factors; and the more variants an individual inherited, the greater the risk of vitamin D deficiency.
"It's possible that these results could explain why some people respond well to vitamin D supplements and others don't, but that needs to be studied further since we didn't specifically examine response to supplementation," explained Wang.
"We also need to investigate how genetic background can modify response to sunlight, whether these associations are seen in other populations, and if these gene variants have an impact in the chronic diseases that appear to be associated with vitamin D deficiency," he added.
The study will appear in The Lancet.