The research suggests that the majority of the American population is vitamin D deficient, leaving them at increased risks from bone disorders, and many other diseases. The data, which was presented at a recent American Association for Clinical Chemistry (AACC) meeting also suggested that testing individuals at risk of deficiency may be beneficial
"There are many factors that contribute to people having low vitamin D status," said Dr Neil Binkley, an associate professor of Endocrinology and Geriatrics at University of Wisconsin School of Medicine and Public Health.
"Low dietary intake, sun avoidance, age and geographic location all play a part. It is important to measure vitamin D in some individuals who may be at risk because of all of variables that may cause low vitamin D," he added.
Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former, produced in the skin on exposure to UVB radiation (290 to 320 nm), is said to be more bioactive.
Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body.
Low vitamin D can lead to skeletal disorders, such as rickets in children and bone loss in adults, and has been linked to an increased risk of hip fractures.
Although research is still being conducted in this area, some studies have also suggested that people with a low level of vitamin D may have elevated risks for several other diseases, including, cardiovascular problems, autoimmune disorders, multiple sclerosis, and some infectious diseases.
While our bodies do manufacture vitamin D on exposure to sunshine, the levels in some areas 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.