Vitamin D is a fat-soluble vitamin available as a dietary supplement and is naturally present in very few foods. This is the only vitamin which can also be produced by the sunlight when it strikes the skin and trigger vitamin D Synthesis. Vitamin D produced by the sunlight is biologically inert therefore it has to undergo for two hydroxylations in the body for activation.
Vitamin D is very important for our body as it helps in absorption of calcium in the gut and to maintain serum calcium and phosphate concentrations which prevents hypocacemic tetany. It is also be used by our body for bone growth and it’s remodelling by osteoblasts and osteoclasts. Other than this vitamin D blocks the release of parathyroid hormone. This hormone is responsible for reabsorption of bone tissue, which makes bone brittle and thin.
There are reference intake values for vitamin D given by Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of The National Academies (formerly National Academy of Sciences). The reference values are as follows-
- Recommended Dietary Allowance (RDA): Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals.
- Adequate Intake (AI): Intake at this level is assumed to ensure nutritional adequacy; established when evidence is insufficient to develop an RDA.
- Estimated Average Requirement (EAR): Average daily level of intake estimated to meet the requirements of 50% of healthy individuals; usually used to assess the nutrient intakes of groups of people and to plan nutritionally adequate diets for them; can also be used to assess the nutrient intakes of individuals.
- Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects.
The level of vitamin D should not be less than 12ng/ml as it indicates Vitamin D deficiency. The level of 20ng/ml to 50 ng/ ml is considered to be adequate for healthy people.
Groups which are at risk of vitamin D Deficiency are-
- Breastfed Infants
- Older adults
- People with limited sun exposure
- People with Dark skin
- People with Inflammatory Bowel disease and other conditions causing Fat Malabsorption
- People who are obese or undergone gastric bypass surgery
Diseases caused by vitamin D deficiency are-
- Getting Sick or infected often
- Tiredness or fatigue
- Bone and Back pain
- Impaired wound Healing
- Bone Loss
- Hair loss
- Muscle pain