Vitamin D is available in several different forms. Two forms of vitamin D are important to human beings – vitamin D2 and D3. Vitamin D2 is made by plants and vitamin D3 is made by human skin on exposure to sunlight.
Physiological role
Vitamin D mainly helps human body to maintain normal blood levels of calcium and phosphorus. Along with calcium it increases strength of bones and decreases risk of fractures. It also helps to prevent loss of bone mineral, the condition known as osteoporosis. Apart from these, vitamin D has role in treatment of certain cancers and other diseases.
Deficiency of vitamin D
Deficiency of vitamin D leads rickets and osteomalacia. These two are commonest diseases caused due to deficiency of vitamin D. Both the diseases cause weakening of bones. Rickets occur in children, whereas osteomalacia occurs in adults. People in risk of developing vitamin D deficiency are elderly, obese, exclusively breastfed babies, people with limited exposure to sun. Certain diseases also increase the risk of developing vitamin D deficiency.
Rickets
Rickets, as mentioned before, results in weakening of bones in children. Signs and symptoms of rickets are muscle weakness, pain in legs, spine and pelvis etc. Severe and untreated cases of rickets may result in bony deformities. Most common cause of rickets is vitamin D deficiency. Children get vitamin D from food and sunlight. Lack of vitamin D from these sources is important precipitating factor. Some diseases in children interfere with absorption of vitamin D and lead to development of rickets.
Diagnosis of rickets is usually made by the doctor through clinical examination. Additionally doctors ask for x-rays of the affected bones to evaluate bony deformities. Mainstay of treatment is vitamin D and calcium supplementation in children. Doctors recommend the doses of these drugs as per the need of the patient. Bony deformities are corrected by surgical procedure. In order to protect children against developing rickets they should be fed with foods containing natural vitamin D or fortified with vitamin D.
Osteomalacia
Weakening of bones in adults is known as osteomalacia. Most commonly patients with osteomalacia present with dull aching pain in the bones of hips, pelvis, legs and lower back. Occasionally it is accompanied by muscle weakness. Most important cause of osteomalacia is vitamin D deficiency. Certain surgeries and diseases may also lead to osteomalacia. Osteomalacia increases the risk of fracture of bones in adults. Estimation of blood levels of calcium, phosphorus and vitamin D are required and along with the x-rays to confirm the diagnosis. Patients with osteomalacia are required to take calcium and vitamin D supplementation for a prolonged period. Diet containing natural vitamin D or food fortified with vitamin D can prevent osteomalacia. The recommended daily allowance of vitamin D is 600 international units in adults.
In order to detect vitamin D deficiency, especially in elderly subjects, periodic blood estimation of vitamin D, calcium and phosphorus may be done.
