Vitamin D Deficiency
Vitamin D helps in the absorption of calcium and phosphorus from food and is essential for maintenance of strong and healthy bones. It is also important for normal functioning of the muscles and overall good health. Vitamin D deficiency is associated with an increased risk of diseases such as cardiovascular disease, cancer, diabetes, autoimmune disease, cognitive impairment in elderly and severe asthma in children.
Skin can synthesize vitamin D from cholesterol on exposure to UVB rays of the sun and this fulfils most of the body’s vitamin D requirements. Vitamin D is also present in a few natural foods that include:
- Oily fish such as North Sea salmon, herring, mackerel and sardines
- Liver and cod liver oil
- Egg yolk
Oily fish and cod liver oil are good dietary sources of vitamin D. Some foods such as milk and margarines are fortified with vitamin D.
Vitamin D deficiency may occur due to various reasons including:
- Insufficient synthesis of Vitamin D: This may occur if exposure of the skin to the sun is limited. Thus, people who spend most of their time indoors, always wear long sleeves and pants, and those who always use sunscreen with SPF factor higher than 15 are at an increased risk of vitamin D deficiency. The risk is higher in people with dark skin and elderly people because of the inherent inability of their skin to synthesize sufficient vitamin D.
- Pure vegetarian diet
- Problem in absorption and metabolism of vitamin D: Certain medical conditions such as crohn’s disease, cystic fibrosis, celiac disease or liver disease affect the ability of the intestine to absorb vitamin D from food and may lead to vitamin D deficiency. Kidneys convert vitamin D to its active form. Thus, any kidney problem can increase the risk of vitamin D deficiency.
- Obesity: Vitamin D is a fat-soluble vitamin. People with a body mass index ≥ 30 are at a higher risk of vitamin D deficiency as all the vitamin D in the blood is taken up by the fat cells and its availability for other bodily functions is significantly reduced.
Symptoms of vitamin D deficiency
In children, vitamin D deficiency may lead to late teething and dental deformities, reluctance to start walking, irritability, susceptibility to infections, impaired growth, short stature, bone pain and muscle pain. Severe vitamin D deficiency in children is called rickets and may cause muscle cramps, breathing difficulties, seizures and skeletal deformities such as bow legs, pigeon chest, pelvic and spinal deformities (scoliosis and kyphosis).
In adults the symptoms are very subtle and may include general aches and pains and tiredness. Severe deficiency in adults is called osteomalacia and results in severe pain in lower back, hips, pelvis, thighs and feet along with muscle weakness. Affected individuals experience difficulty in climbing stairs and getting up from the floor or low chairs due to muscle weakness.
The simplest and most accurate method to diagnose vitamin D deficiency is estimation of 25-hydroxy vitamin D levels in blood. Value <12 ng/ml indicates vitamin D deficiency.
Treatment involves vitamin D supplementation in the form of tablets, powders, liquids or injection. The dose and the appropriate treatment schedule depend on the age and severity of the deficiency. Usually a maintenance dose of vitamin D is recommended, even after the treatment, to prevent any further deficiency in the future.