Vitamin D plays a role in numerous bodily functions, including regulating the immune system. It's best-known role is in bone health. Vitamin D helps your body absorb calcium, which helps build and maintain strong bones. You get vitamin D from sources such as sun exposure, eggs, fortified milk and fatty fish like salmon, tuna and mackerel. Deficiencies can result from too little sun exposure, inadequate intake and impaired absorption. An adequate vitamin D level is 20 nanograms per milliliter or higher, according to the Office of Dietary Supplements.
Low Vitamin D
In adults, vitamin deficiency causes bones to weaken and become soft. In children, this is known as rickets. This occurs because without vitamin D, the bones are unable to harden in a process known as mineralization. Scientists are still learning what other issues vitamin D deficiency may cause. Too little vitamin D may increase the risk of high blood pressure, obesity, depression and certain cancers, according to the University of Maryland Medical center. More research is needed in these areas.