What causes vitamin D deficiency?

Vitamin D deficiency means having a low level of vitamin D in the body. RDA of vitamin D is different in different age groups; but generally when the vitamin levels fall low than the range of 400 IU-800IU, vitamin D deficiency is said to occur.


There are many causes of vitamin D deficiency. It can occur in any age group and can have a number of causes; from malnutrition to malabsorption.

  • Vitamin D deficiency may arise if the vitamin intake is low or the body has a greater need. The low intake is usually seen in people coming from areas with lower socio-economic condition. Also, people who are strict vegetarians and consume no fish at all in their food can get vitamin D deficiency.
  • The body develops a greater need for the vitamin D during conditions such as pregnancy; this is because, a part of the mother’s diet goes to the baby. If the mother is deficient in the vitamin, all of her vitamin stores may be used up and ultimately vitamin D deficiency may develop. The mother’s bones may also start to thin resulting in fractures.This is not it; the babies that are breast fed by vitamin D deficient mothers will also suffer with vitamin D deficiency. Therefore, it is important for all the lactating mothers to take supplements to prevent any deficiencies in the baby.
  • Another reason for the development of vitamin D deficiency may be the color of the skin. Vitamin D deficiency is common in dark skinned people. The darker the skin, the lesser the penetration of UVB rays and the lesser is the formation of vitamin D. fair-skinned people on the other hand have no problems in making vitamin D from the sun.
  • Vitamin D deficiency may arise in people who stay indoors and do not have enough exposure to the sunlight. This type of deficiency may arise in people who are house bound either due to work or age (elderly).
  • Sun exposure is also limited in females who wear clothes that expose too little or almost no area of skin for the formation of vitamin D. this type of deficiency may be commonly seen in females of tribal areas.
  • Sunscreen use can also limit the amount of sunlight penetrating the skin, hence limiting the amount of vitamin D formation from the skin. Usage of creams with SPF (aka sun protection factor), typically SPF-8 can limit the vitamin D formation in skin for up to 95%. The creams with SPF 15 or higher may also be harmful.
  • Old age can also have its effect on vitamin D synthesis. The geriatric population is prone to the vitamin D deficiency owing to the thinness of their skin. The thinner their skin, the lesser is the formation of vitamin D.
  • Obesity may also cause hypovitaminosis. Obesity means having extra fat in the body. Vitamin D is a fat soluble vitamin; it is stored and extracted from the fat stores of the body and then circulated in the blood. People with a body mass index (BMI) equal to or greater than 30 may develop vitamin D deficiency.
    Body mass index or BMI is ratio of a person’s mass (or weight) and their height. BMI helps to determine if a person has excess body fat (obesity).


  • Certain diseases of the small intestine that prevent the absorption of substances through the intestinal wall are also responsible for the deficiency states. However, these deficiencies are not limited for a vitamin or two, they involve a number of other substances and a general deficiency state develops in the body. This kind of vitamin D deficiency presents in patients with Crohn’s disease, Celiac disease and cystic fibrosis.


  • Since liver and kidney are primary organs after the skin, involved in vitamin D metabolism, any diseases that impair liver or kidney’s function can cause vitamin D deficiency in the body. In people with liver failure and kidney failure, vitamin d deficiency can commonly be encountered, since these organs have lost the ability to convert the vitamin D into its active form. Vitamin D supplements may be added to their prescriptions to compensate for the loss.


How to see if you are vitamin D deficient?

Vitamin D deficiency may manifest with its own typical symptoms but another easier way to make sure if you have normal levels of vitamin D in your body is to get it checked by a simple blood test.

The test checks the amount of 25-hydroxycholecalciferol in your blood. This form of vitamin D is the storage form in the blood. This form is hydroxylated to 1,25-di hydroxyl cholecalciferol by the kidney when the vitamin D is needed in the body.


Different diseases will show different signs and symptoms with vitamin D deficiency. Before starting any supplements it is best to consult your doctor for confirmation whether there is a mere deficiency or collective deficiency associated with a disease. The treatment of a primary cause is good to proceed with rather than just finishing off with the supplements.

In the end, a healthy life is a happy life.