Sources of Vitamin D

Vitamin D, a fat soluble vitamin, plays an important role in calcium deposition in our body. As it encourages calcium deposition, it is also called as calciferol. Calciferol exists in different forms. Ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) are the major forms of calciferol.

Exposure to sunlight is the best source for gaining vitamin D. Vitamin D is produced in our skin ,when it is exposed to the ultraviolet radiations of the sun. However, the amount of radiations received, differ due to climatic changes. Ten minutes of exposure of face and arms to sunlight, at least thrice a week, provides the essential vitamin D. However, exposure to sunlight in cold countries is negligible. Therefore, the people in these parts must follow a diet containing vitamin D-rich foodstuffs.

Functions of Vitamin D

• Vitamin D plays an important role in skeletal growth as well as the formation of bone and teeth in our body.
• Its major function is helping in calcium absorption. If calcium absorption is inadequate, bones become weak, misshapen and brittle.
• Vitamin D helps in assimilation of calcium and phosphorous and also maintains their adequate levels in our body.
• The parathyroid hormone regulates calcium and phosphorous concentration in our body. Vitamin D suppresses parathyroid hormone secretion from parathyroid glands, so that excessive calcium is not absorbed in the body.

Sources of Vitamin D

Milk: An excellent amount of vitamin D is found in milk. Almost all the milk supplied in the United States, is fortified with vitamin D. One cup of milk daily, provides the required amount of vitamin D.
Fatty Fish: All fatty fish like mackerel, sardines, tuna, herring, salmon are the best sources of vitamin D.
Cod Liver Oil: This supplement obtained from cod fish contains high levels of vitamin D.
Eggs: Whole egg, especially egg yolk, is a good source of vitamin D.
Bread: Bread, fortified with vitamin D, is useful in providing the necessary nutrition.

Vegetarians also have some options of vitamin-rich sources.

• Cow's milk and soy milk are rich in vitamin D.
• Vitamin D-fortified cheese and margarine will provide the required vitamin D.
• There are also vitamin D-fortified cereals and juices available in the market.

In some countries, providing vitamin D-fortified margarine, milk or cereals is mandatory for the concerned food industry. This helps in minimizing vitamin D deficiency diseases.

Diseases related to Vitamin D

It must be noted that excessive intake of vitamin D is harmful. It causes nausea, anorexia (loss of appetite) and vomiting. It affects the kidney causing polydipsia (excessive thirst) or polyuria (excessive urine). Vitamin D overdose can cause kidney stones or even complete kidney failure (renal failure).

People avoiding sunlight (in Middle Eastern countries) and people living in cold countries are mostly found to be deficient in vitamin D. Deficiency of vitamin D can result in numerous diseases. It causes a disease known as rickets in children, wherein obstructed growth and deformity of long bones is observed. In adults, deficiency of vitamin D causes osteomalacia (softening or thinning of bones, due to lack of calcium) or osteoporosis (loss of bony tissue, due to deficiency of calcium). Sometimes, liver or kidney disorders or dental caries are also seen.

As these diseases are deficiency diseases, they can be prevented by having an adequate intake of vitamin D. Hence, it is very essential to follow a balanced diet, to maintain proper amount of vitamin D in our body.