Vitamin D (also called calciterol) is a fat soluble vitamin. This means that in order for it to be absorbed by the intestinal tract, fat must be present. People who have disorderscystic fibrosis for example- that prevent their bodies from absorbing fat may become deficient in vitamin D. This deficiency can occur even if the person's diet includes plenty of foods rich in vitamin D. These foods include Vitamin A&D fortified milk, butter, egg yolks, yogurt, sour cream, cheeses and fatty fish.
There are a number of conditions that may cause a person to become deficient in vitamin D.
Cystic fibrosis (CF) is an inherited genetic disease in which the body produces excess thick, sticky mucus. In many patients with CF, the pancreas is blocked by this mucus and cannot secrete the enzymes needed to help the intestine absorb nutrients from food. In addition, fat absorption is very difficult, resulting in a deficiency in all fat soluble vitamins, particularly vitamin D.
Crohn's disease causes the lining of the digestive tract to become inflamed. The result is painful swelling and discomfort of the abdomen, and often presents with frequent diarrhea. Persistent inflammation and diarrhea make it very difficult for the body to adequately absorb nutrients and vitamins, resulting in vitamin D deficiency.
Colitis, similar to Crohn's disease, is an inflammatory condition. Specifically, it is the colon that is inflamed. Also called inflammatory bowel disease or IBD, ulcerative colitis causes the colon to empty itself more frequently than normal. Occasionally ulcerative colitis may involve the small intestine, interfering with the body's ability to absorb vitamins and nutrients. Frequent diarrhea associated with the condition can result in vitamin D deficiency.
A chronic autoimmune disease, lupus causes arthritis pain, fatigue and skin rashes. People with lupus are sometimes encouraged to avoid prolonged exposure to sunlight because of their bodies' photosensitivity. Without enough exposure to the sun's UV rays, the body cannot synthesize vitamin D. As a result, lupus patients are deficient in this fat-soluble vitamin and must take vitamin supplements.
There are two forms of vitamin D. The first is called D2, the source of which is primarily plants. The other form of vitamin D is D3, which is the vitamin D that the body is able to synthesize or create on its own when the skin receives direct exposure to UV rays from the sun. Without vitamin D of either form, the body cannot absorb calcium. Without adequate amounts of calcium, the body becomes prone to conditions like rickets, osteomalacia, osteoporosis, convulsions and muscle twitching.
The recommended daily allowance (RDA) of vitamin D for healthy adult males and females is 5 micrograms. Cystic fibrosis patients need far more as determined by a blood test to check their vitamin levels.