Vitamin D is a fat soluble vitamin. It is particularly essential for bone health and functioning of immune system in our body. Vitamin D helps our body absorb calcium and phosphorus, and maintain strong bones and teeth.

Six common causes of Vitamin D deficiency:

1. Lack of exposure to sunlight
2. Dietary deficiency of vitamin D
3. Liver and kidney diseases
4. Poor food absorption in cystic fibrosis and Crohn’s disease, and in patients who have undergone gastric bypass surgery
5. Use of certain medicines, including phenytoin, phenobarbital, and rifampin etc can cause vitamin D deficiency
6. In infants who are exclusively breastfed. Formula milk is fortified with vitamin D.

Six common symptoms of Vitamin D deficiency:

1. Frequent bone fractures due to thinning and brittle bones
2. Bone and back pain
3. Frequent Infections
4. Feeling exhausted or tired
5. Mood swings with anxiety or depression
6. Impaired wound healing

Health risks associated with vitamin D deficiency

Vitamin D deficiency can result in serious health conditions like Osteomalacia in adults, Rickets in children and Osteoporosis.

Osteomalacia is a characteristic feature of vitamin D deficiency in adults. Osteomalacia is softening of bone due to demineralization (the loss of mineral) and most notably by the depletion of calcium from bone.

Vitamin D deficiency in children can result in Rickets. Rickets results in softening and bending of bones. Osteoporosis is a condition of fragile bones with increased susceptibility to fracture. Vitamin D and calcium deficiency are one of the leading cause of osteoporosis.

Research is also being conducted to study the possible relation of Vitamin D with several medical conditions, including diabetes, hypertension (high blood pressure), cancer, and autoimmune conditions such as multiple sclerosis. But, it will be too early to comment anything on this.

Vitamin D is derived from endogenous sources and exogenous sources.

. Endogenous source:It is produced in our body on exposure of our skin to sunlight.
. Exogenous source: Dietary source of the vitamin D includes fish, eggs, fortified dairy products and dietary supplement.

Vitamin D requirements depend on a number of factors like age, race, geographical location, season, sun exposure etc. A daily Vitamin D intake of 1000–4000 IU, or 25–100 micrograms, should be enough to ensure optimal blood levels in most people.

In case you are Vitamin D deficient, you can treat this condition by getting more Vitamin D through diet and supplements. Increased exposure to sunlight also helps as Vitamin D is produced in our body on exposure of skin to sunlight.

Consult your doctor to know about how much Vitamin D supplements you need to take, how often you need to take it, and how long you need to take it in case you are Vitamin D deficient.

Excess supplementation of Vitamin D can result in Vitamin D intoxication. Vitamin D levels can easily be monitored by a simple Vitamin D blood test.

The normal range of Vitamin D 25-OH is measured as nanograms per milliliter (ng/mL) or nmol/L and can vary from lab to lab.

Level	Reference range	(ng/mL)
	Severe deficiency	<10 ng/mL
	Mild to moderate deficiency	10-24
	Optimal	25-80
	Potential intoxication	>80

Note:

•There can be seasonal variation in 25 (OH) vitamin D level, with values being 40-50% lower in winter than in summer. It is also influenced by sunlight, latitude, skin pigmentation, sunscreen use, and hepatic function.

•25 (OH) vitamin D levels can vary with age

•25 (OH) vitamin D level is increased during pregnancy.