Most people are deficient in Vitamin D. Vitamin D can be found as vitamin D2 (“ergocalciferol” or pre-vitamin D) (produced in plants and fungi) and vitamin D3 (“cholecalciferol”) (animals, including humans). Both D3 and D2, the precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), which is the non-active ‘storage’ form, and 1,25-dihydroxyvitamin D (1,25(OH)2D) (also called as calcitriol), the biologically active form that is controlled / regulated by the body.
Sunlight (Ultraviolet Light)
The body makes vitamin D, when the skin absorbs the ultraviolet B (UVB) rays of the light spectrum. The further away from the Equator, the less UVB light reaches the earth’s surface. The Pollution in the air diminishes the UVB rays. Overdose on UVB, increasing their risk of malignant melanomas and other skin cancers. (image courtesy : https://www.grassrootshealth.net/document/sunshine-calendar/)
Most dietary supplements are manufactured by exposing a plant sterol to UV energy, thus producing vitamin D2. Because their function is almost identical, D2 and D3 are lumped together under the name vitamin D — but neither will function until the body works its magic. A meta-analysis of randomised controlled trials that compared the effects of vitamin D2 and D3 supplements on blood levels found that D3 supplements tended to raise blood concentrations of the vitamin more (image courtesy : https://www.grassrootshealth.net/document/sunshine-calendar/)
Dietary Sources (from Food)
Diet can help, but it’s very hard to approach the goal with food alone. Fish and shellfish provide natural vitamin D (oily fish are best), but you would have to consume a lot for the daily requirement itself. Some fortified products like milk, yogurt, orange juice, cereals are available. But in general, a serving will provide only about 100 IU.
Desk jobs, sunscreen, pollution, unhealthy eating have changed a lot of things. This had made vitamin D a dilemma of modern life.
So, a modern solution: eating fish and/ or drinking some low-fat fortified milk, along with judicious doses of vitamin D supplements and 10 – 30 mins of exposure to UVB (refer to the image).