Lack of sunshine and an unvaried diet can contribute to vitamin D deficiency, but according to new research, so can genetics.

An international group of researchers and doctors analyzed data from nearly 34,000 adults of European ancestry, looking specifically at genetics and vitamin D concentration levels in the blood

The researchers found three gene variants – those involved with cholesterol, vitamin D metabolism and transporting vitamin D through the body – were associated with vitamin D deficiency. The more of these variants an individual had, the researchers said, the greater the risk of having low vitamin D levels, according to WebMd.

Vitamin D assists in calcium absorption, helping form and maintain strong bones. Research also suggests the vitamin provides protection from osteoporosis, high blood pressure and several autoimmune diseases.

Participants who had inherited several of the gene variants were two-and-a-half times more likely to have a vitamin D deficiency, compared to those whose genetic background was least disposed to the problem, according to the study, published in The Lancet.

Nearly half of healthy adults in developed countries are deficient in vitamin D, according to WebMD. Recent research also suggests older adults, teens and even infants are at raised risk of vitamin D deficiency.

Knowing who carries the gene variants, however, could help doctors identify who is at risk for vitamin D deficiency and could potentially help reduce the risk of low vitamin D before the problem advances.

"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," study co-author Thomas Wang said to WebMD.

The body naturally produces vitamin D when exposed to ultraviolet rays, but concerns about skin cancer and the heavy use of sunscreen have contributed to a deficiency in large populations. Vitamin D is also found in some food sources, including fatty fish, such as salmon, tuna and mackerel, cheese and eggs.