Vitamin D in a sunny country: why deficiency is common in India and what to do about it

India gets more usable sunlight than most of the world and has one of the higher reported rates of vitamin D deficiency. Indian studies and meta-analyses put deficiency somewhere around two thirds of the population, with several urban samples reporting considerably more. The paradox has ordinary explanations.

Why the sun is not enough

• Melanin is a natural sunscreen. Deeper skin tones need substantially longer exposure to make the same amount of vitamin D.
• Indoor work and indoor leisure. Skin that never meets midday sun does not synthesise anything.
• Clothing that covers most of the body, which is the norm in much of the country.
• Air pollution, which scatters the UVB wavelengths responsible for synthesis - a real effect in Indian cities.
• Sensible sun avoidance for skin health, which works against vitamin D synthesis by design.
• A largely vegetarian diet: the significant food sources are oily fish, egg yolk and fortified products.

The ICMR-NIN RDA is 600 IU (15 micrograms) a day for most age groups, and the 2024 dietary guidelines emphasise adequate sun exposure alongside diet.

When testing is worth it

The test is 25-hydroxy vitamin D. It is not a test everybody needs, and routine population screening is not recommended - but it is worth doing when there is a reason.

• Persistent bone or muscle aches, proximal muscle weakness, or unexplained fatigue.
• Osteoporosis, a fragility fracture, or long-term steroid use.
• Malabsorption conditions - coeliac disease, inflammatory bowel disease, after bariatric surgery.
• Chronic kidney or liver disease.
• Pregnancy, or an infant not receiving recommended supplementation.
• Before starting a high-dose regimen, so there is a baseline to measure against.

Weekly 60,000 IU sachets are prescribed widely in India and are appropriate for treating a diagnosed deficiency for a defined period. Taking them indefinitely without monitoring is how people reach toxicity - which causes high calcium, nausea, kidney stones and worse. Correction and maintenance are different doses for different durations.

The forms, briefly

Sun, sensibly

For most people, short midday exposure on arms and legs a few times a week contributes usefully, with the required duration longer for deeper skin tones. Glass blocks the relevant UVB, so sitting by a window does not count.

This has to be balanced against sun damage and pigmentation, which are the reasons dermatologists recommend protecting the face specifically. A workable compromise many people land on: protect the face daily, let forearms and lower legs take brief regular exposure, and supplement rather than seek out burning.

Food sources in an Indian context

• Fatty fish - rohu, sardines, mackerel - are the best natural sources available here.
• Egg yolk contributes modestly.
• Fortified milk, fortified oils and some fortified atta carry the +F logo and contribute a little.
• Mushrooms exposed to UV contain D2, and sun-drying mushrooms at home genuinely increases it.
• No plant food is a reliable primary source, which is why supplementation is commonly needed by vegetarians here.

Vitamin D is one of the few supplements with a genuine population-level case in India. It is also one where a test, a defined correction course and a maintenance dose beat indefinite self-medication - so get the number, then decide.