The Causes Of A Slight Vitamin D Deficiency

Vitamin D consists of five fat-soluble compounds called secosteroids. The D2 and D3 forms are the most essential for human biochemistry. Vitamin D2, named ergocalciferol, is obtained exclusively from the diet or through supplementation. Vitamin D3, named cholecalciferol, is produced by the skin when struck with ultraviolet radiation from sunlight. A 2009 edition of "Scientific American" reported 75 percent of U.S. teens and adults are vitamin D deficient.

Lack of Sun Exposure

The most widespread cause of vitamin D deficiency is lack of appropriate sun exposure, as cited by Merck Manuals Online Medical Library. In some geographical locations, such as the extreme latitudes, sunshine is severely limited during some months. In urban areas, pollution or cloud cover can reduce 50 percent of more of the sun's radiation. Even in sunny climates, sedentary indoor lifestyles, fear of skin cancer and popular use of sun screens severely reduce exposure to necessary sunshine.

The U.S. Department of Agriculture recommends 200 IU of vitamin D per day for adults up to the age of 50 years, which is a dated measurement meant to abate acute deficiency symptoms. Higher daily levels are needed for normal health, although there is debate over optimal and safe amounts. For comparison, a fully exposed Caucasian adult produces about 10,000 IU of vitamin D3 in response to 20 minutes of mid-summer sun exposure.

Poor Nutrition

If access to sunshine is limited, then a person must consume foods rich in vitamin D2 or take supplements. Unfortunately, vitamin D is not in most foods, which makes it challenging to consume even 200 IU per day on a regular basis. Foods naturally rich in vitamin D2 include fish and fish oils, liver and egg yolks. Foods usually fortified with vitamin D include milk, breakfast cereals and orange juice. Dietary deficiency of vitamin D is found more often in those with milk allergies, lactose intolerance and vegetarian diets. Supplemental forms of vitamin D2 and D3 are widely available, but few have the information and money to use them effectively.

The National Institutes of Health cites that blood serum concentration of calcidiol is the best indication of vitamin D status, and measurements below 37.5 nanomoles per liter are considered deficient. To be utilized in the body, however, vitamin D needs other nutrients as co-factors, such as magnesium, zinc, vitamin K2, boron and vitamin A. Magnesium is especially important and a dietary deficiency of magnesium can lead to a vitamin D deficiency.

Diseases

Even if a person gets adequate sunshine, eats vitamin D rich foods and takes supplements, some diseases and conditions prevent the body from utilizing vitamin D. Merck cites that lowered absorption of vitamin D can occur with pancreatitis, celiac disease, Crohn's disease, cystic fibrosis, colitis and biliary obstruction. Liver and kidney diseases can interfere with vitamin D absorption or its transformation into calciferol. A parathyroid gland pathology and reduced production of parathyroid hormone interferes with activation of vitamin D in the kidneys.