Vitamin D is crucial in humans' ability to absorb calcium, and it also plays a role in immunity, anti-inflammation, and neuromuscular functioning, yet it is one of the few vitamins that are not readily available in our food. Our bodies must produce vitamin D via our skin's exposure to sunlight. If this process is interrupted, vitamin D deficiency will result if people do not take supplements. There are several symptoms of vitamin D deficiency.
Because vitamin D is produced by the body only upon adequate exposure to sunlight, several types of individuals are susceptible to deficiency: infants, people with limited sun exposure, the elderly, people who are obese, and those who have disorders leading to problems absorbing fat. These individuals should be monitored closely for symptoms of vitamin D deficiency.
In infants, a deficiency of vitamin D can lead to problems in proper bone formation. One result is rickets, a painful condition in which the bones of the legs bow outward and the spine may become abnormally curved. Very young infants may have soft, underdeveloped skulls, and as they get older, may be delayed in beginning to walk. Muscle spasms are often the first symptom of rickets. Breastfeeding alone does not provide adequate vitamin D, so breastfed infants must be supplemented.
Osteomalacia, or softening of the bones, is a major symptom of vitamin D deficiency. This results in pain in the muscles and bones, but these symptoms often go unnoticed or are attributed to other causes in the initial stages. Fractures occur very easily, especially in the elderly. Because it is crucial in helping the body to absorb calcium, vitamin D deficiency can cause or contribute to osteoporosis.
Because the symptoms of vitamin D deficiency can be subtle, those individuals who are at risk should have their levels tested. The best indicator is the serum level of 25-hydroxyvitamin D, or 25(OH)D, which is another term for calcidiol, the circulating form of vitamin D. This test reflects how much vitamin D is in your blood, both what your body has produced from the sun and what you've taken in with food and supplements. The diagnosis of both rickets and osteomalacia is based on a combination of the 25(OH)D results, bone X-rays, and symptoms.
Treatment & Prevention
Treatment of vitamin D deficiency includes high doses given as an oral supplement or injected directly into the bloodstream for a period of one to two months. Prevention includes getting adequate sunlight and taking supplements. There are few foods that contain vitamin D; these include fatty fish and fish liver oils, cheese, and egg yolks. Many dairy foods in the United States are fortified with vitamin D, but this is not the case in many parts of the rest of the world.