Vitamin D Deficiency: Why It Is So Common in India

A Sunny Country With a Deficiency Problem

India gets more usable sunlight than almost anywhere in the world, and yet study after study finds that between 70 and 90 per cent of the population is vitamin D deficient. It is the paradox we explain most often in clinic. The sunlight is there; what has changed is how much of it reaches our skin, and how well our skin converts it.

Vitamin D is not really a vitamin. It behaves as a hormone, and its main job is to let the gut absorb calcium. Without enough of it, calcium is pulled out of bone instead, and the parathyroid glands work overtime to hold blood calcium steady — which is where the aches, the fractures and the fatigue come from.

Why Deficiency Is So Widespread Here

• Indoor lifestyles. Office and school hours cover exactly the window — roughly 10 am to 3 pm — when UVB rays are strong enough to make vitamin D at all.
• Skin pigmentation. Melanin is a natural sunscreen. Darker skin needs three to five times longer in the sun to produce the same amount.
• Clothing and sunscreen. Full-cover clothing and daily SPF, both entirely reasonable choices, block almost all vitamin D synthesis.
• Air pollution. Particulate haze over most Indian cities scatters UVB before it reaches street level.
• Diet. Very little vitamin D occurs naturally in a predominantly vegetarian diet, and food fortification here is limited compared with the UK, US or Europe.
• Body weight. Vitamin D is fat-soluble and gets sequestered in fat tissue, so requirements are higher in obesity.
• Medical causes. Coeliac disease, inflammatory bowel disease, bariatric surgery, chronic kidney or liver disease, and medicines such as anti-epileptics and steroids all reduce levels.

Sitting behind glass does nothing at all — window glass blocks the UVB wavelengths entirely. Neither an office window seat nor a car commute counts as sun exposure.

Symptoms That Are Easy to Dismiss

Mild deficiency is often silent. As it deepens, the pattern is characteristic but non-specific:

• Persistent tiredness and low stamina
• Aching bones, especially the lower back, hips, pelvis and shins
• Muscle weakness — difficulty climbing stairs or rising from a squat
• Muscle cramps and, when calcium falls, tingling around the mouth and in the fingers
• Low mood and disturbed sleep
• Hair fall and slow wound healing
• Frequent infections
• Fractures from minor falls, or a bone density scan showing osteoporosis

In children, severe deficiency causes rickets — bowed legs, delayed walking and delayed teeth. In adults the equivalent is osteomalacia, which is frequently mislabelled as fibromyalgia or arthritis for years before anyone tests for it.

The Right Test and What the Numbers Mean

The correct test is serum 25-hydroxy vitamin D, written as 25(OH)D. The active form, 1,25-dihydroxy vitamin D, is not a screening test and is often normal even in significant deficiency — ordering it wastes money and gives false reassurance.

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Where deficiency is severe or recurrent we also check serum calcium, phosphate, alkaline phosphatase, parathyroid hormone and kidney function, because the deficiency is sometimes a symptom of something else rather than the whole diagnosis.

Correcting It Properly

Sunlight

Twenty to thirty minutes between 10 am and 3 pm, on the arms, legs and back rather than the face alone, three to four times a week. Darker skin needs longer. This maintains a level far more easily than it corrects a deficiency, so it is the follow-up strategy, not usually the treatment.

Diet

Fatty fish, egg yolk, fortified milk and cereals, and mushrooms exposed to sunlight are the practical sources. In a vegetarian diet, diet alone will not correct a deficiency, which is why supplementation is the mainstay here.

Supplements

Deficiency is usually corrected with a weekly loading dose of cholecalciferol (D3) for six to eight weeks, followed by a maintenance dose. Adequate dietary calcium must accompany it, otherwise you are opening a door with nothing behind it. Levels are rechecked after about three months — not sooner.

Vitamin D is stored in fat, so more is not better. Very high doses taken indefinitely without monitoring cause high calcium, kidney stones and kidney damage. This is one of the few deficiencies where self-medication genuinely causes harm. Our bone and calcium disorders service manages replacement alongside bone density and parathyroid assessment.

When to See an Endocrinologist

Book a review if your levels stay low despite supplementation, if you have bone pain or a fracture from a minor fall, if your calcium or parathyroid readings are abnormal, if you have had bariatric surgery or a malabsorption condition, or if you have osteoporosis on a DEXA scan. Vitamin D deficiency often coexists with thyroid disease and diabetes, and is worth reviewing together with them.

Conclusion

Vitamin D deficiency in India is not caused by a shortage of sun — it is caused by indoor hours, covered skin, pollution and a diet with almost no natural source of it. That is why it affects office workers, homemakers and the elderly alike.

The fix is straightforward: test the right marker, correct it with a proper loading course rather than a random weekly capsule, keep calcium intake adequate, and recheck at three months. Done properly, the aches and fatigue usually improve within a few weeks.

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