Why sunny India is still deficient in ‘sunshine vitamin’

We live in a country blessed with abundant sunshine. Despite that, vitamin D deficiency continues to affect millions of Indians. Dr Ravinder Goswami, endocrinologist and professor at AIIMS Delhi and recipient of the Shanti Swarup Bhatnagar Prize, tells TOI why this paradox exists, who are most at risk, and why supplements should never be taken casually.He says vitamin D, often called the “sunshine vitamin”, is far more than just a nutrient for healthy bones. “Without the skeletal system, we cannot even stand. Vitamin D is essential because it helps the gut absorb calcium, and calcium is involved in thousands of functions — from muscle contraction and gut motility to reproduction.”

The Indian paradox

However, the irony is that modern Indian lifestyles have kept people indoors even though there’s plenty of sunshine to bask in.

“Our skin is designed to make vitamin D when exposed to UVB rays. But if we spend our days inside offices, homes or cars, we miss that opportunity,” rues Dr Goswami.Watch the video hereWhen ultraviolet B (UVB) rays strike the skin, they trigger the production of cholecalciferol, an inactive form of vitamin D. The liver and kidneys then convert this compound into its active form as needed. “This is why sunlight remains the best and safest source of vitamin D, but timing is everything,” he says.

The doctor points out that one of the biggest misconceptions is that early morning sunlight is enough. “For vitamin D, the ideal exposure is when the sun is at its peak, generally between 10 am and 3 pm, under cloud-free skies. Sitting beside a sunny window doesn’t help because glass blocks UVB rays.”Fortunately, since India is a tropical country, we don’t need to expose more of our bodies for a bit of sun, unlike the West.

“Sunshine on the face and arms for about half an hour daily is usually sufficient,” he says.Watch the podcast hereFood, however, can only do so much. Fatty fish such as salmon and cod liver contain vitamin D, while UV-exposed mushrooms offer a vegetarian alternative. Fortified milk also contributes, but none of these can meet the body’s entire daily requirement. “We fortify foods to reduce severe deficiency, not to replace sunlight,” explains Dr Goswami.

Why being outdoors matters

Dr Goswami’s landmark research in the late 1990s challenged the belief that Indians could not possibly be vitamin D deficient. His team found that doctors working indoors had surprisingly low vitamin D levels, while traffic police, hawkers and street vendors — people who spent hours outdoors — had adequate levels without supplements.“It wasn’t the food,” he says. “It was sunlight.”The research also highlighted that while higher melanin levels in Indian skin protect against intense sunlight, it also slows down vitamin D synthesis.

So, those with darker skin need significantly longer sun exposure than lighter-skinned populations to produce equivalent amounts of vitamin D. For most healthy people though, sensible sun exposure remains the most effective source.Supplements do play an important role, but Goswami cautions against self-medication. “Injectable vitamin D should generally be avoided unless there is a genuine absorption problem,” he says, noting that large doses can raise calcium levels excessively, increasing the risk of kidney stones and kidney calcification.He also advises against routinely taking active forms of vitamin D or expensive nano formulations: “For most people, standard vitamin D works perfectly well. More is not always better. And supplements should be taken under medical guidance, not as a shortcut to good health.”

Other talking points

Listen to the full podcast on vitamin D here: