Causes of Vitamin D Deficiency

Vitamin D is formed in the skin when the skin is exposed to direct sunlight.

When ultraviolet rays from the sun strike the skin of our bodies, the skin cells in our body called keratinocytes trigger vitamin D synthesis. The endogenously made as well as vitamin D obtained from food are biologically inert (called vitamin D3). D3 is the major circulating form of Vitamin D and is what gets measured in the lab tests. D3 must be metabolized further in the liver and in the kidney to yield activated forms of D called calcidiol and calcitriol, respectively.

Without vitamin D, the body cannot form calcium-binding protein needed for the absorption of calcium from the intestines. Without adequate amounts of calcium, the body becomes prone to conditions like cancer, autoimmune diseases, depression, rickets, osteomalacia, osteoporosis, convulsions and muscle twitching. Vitamin D can be a deterrent for swine flu too.

The Food and Nutrition Board that sets U.S. nutrient recommendations currently recommends 2000 IU of vitamin D per day as a safe upper limit dosage for anyone over one year old.

Many people are deficient in this vitamin. What causes this widespread deficiency that people have to correct with supplements?

Causes for Vitamin D deficiency

• Dark complexion: People who are dark have more melanin or pigment in their skin that makes it harder for the body to absorb and use the sun’s ultraviolet rays to synthesize vitamin D.

• Age: As we grow older, our ability to synthesize and absorb vitamin D decreases.

• Living in high altitudes: If you live in a region above latitude 40, then the sun is only strong enough between May and September to trigger the vitamin D conversion.

• Breast-fed babies: Breast milk is poor in vitamin D and babies who are beast-fed need to receive supplementary vitamin D.

• Kidney or liver damage: This can greatly impair your body’s ability to activate circulating vitamin D.

• Use of sunscreen : Use sunscreen very discreetly (use only for long exposure and only if you’re prone to getting burnt). 

• Body disorders and genetic conditions : Vitamin D is a fat soluble vitamin. Certain disorders prevent the bodies from absorbing fat.

People with Crohn’s disease or colitis have frequent diarrhea caused by inflamed lining of the digestive tract, especially the bowels. The body cannot therefore adequately absorb nutrients and vitamins.

Cystic Fibrosis : This genetic condition blocks the pancreas with a thick and sticky mucus that interferes with the secretion of the enzymes needed to absorb nutrients from food.

Lupus is a condition where the body is sensitive to light and erupts into a rash when exposed to sun. The inflicted persons are therefore advised against prolonged exposure to sunlight. Without enough exposure to the sun’s UV rays, the body cannot synthesize vitamin D.