India sits between 8° and 37° north latitude. Most of the country receives strong, direct sunlight for the majority of the year. By any reasonable calculation, Indians should be among the least vitamin D deficient populations on earth.
Instead, an estimated 70–90% are deficient. The number cuts across urban and rural populations, across income levels, across age groups. A 2025 report by the Indian Council for Research on International Economic Relations found deficiency rates reaching 80–90% in elderly populations, with nearly half of children under ten showing signs of rickets-related bone disease in some studies.
The paradox is real. The explanation is not simple — and understanding it matters for how to actually address the problem.
What Vitamin D Is and Why It Matters
Vitamin D is not really a vitamin in the traditional sense. The body produces it when skin is exposed to UVB radiation from sunlight — making it closer to a hormone than a dietary nutrient. Once synthesised in the skin, it undergoes two further transformations: first in the liver, then in the kidneys, before becoming the biologically active form that the body can use.
Its roles extend well beyond bone health, though that is where most people’s awareness begins. Vitamin D regulates calcium and phosphate absorption, supports immune function, modulates inflammation, and plays a role in muscle function. Deficiency in its most severe forms causes rickets in children — soft, deformable bones — and osteomalacia in adults. In less severe but still clinically significant forms, it is associated with bone density loss, muscle weakness, fatigue, and increased susceptibility to infection.
The consequences of widespread, persistent deficiency in a population of 1.4 billion people are not trivial.
Why Sunlight Alone Is Not Solving It
The intuitive assumption — more sunlight equals more vitamin D — is not wrong in principle. It simply fails to account for several factors that determine how much vitamin D a given person actually synthesises from a given amount of sun.
Skin pigmentation is the primary factor. Melanin, the pigment that gives skin its colour, acts as a natural sunscreen. It absorbs UV radiation — which is precisely why darker skin evolved in high-sunlight environments. But that same protection reduces the skin’s ability to convert sunlight into vitamin D. For Indian skin tones, research estimates that a minimum of 45 minutes of direct daily exposure of bare face, arms, and legs to peak-hour sunlight is required to produce adequate vitamin D. The widely cited “15–20 minutes three times a week” recommendation was derived predominantly from research on lighter-skinned European populations. It does not translate directly to Indian skin.
Urban lifestyles remove the exposure. The majority of urban Indians spend their working hours indoors — offices, schools, factories, homes. The hours when UVB radiation is strong enough to trigger vitamin D synthesis (roughly 10 AM to 3 PM) are precisely the hours when most people are inside. By the time they step outdoors in the evening, UVB levels are too low to be effective.
Air pollution blocks the rays. UVB radiation does not penetrate smog effectively. In cities like Delhi, Mumbai, and Jammu during winter months, pollution levels are high enough to significantly reduce the UVB reaching street level — even on days that appear sunny. A person walking outdoors in a heavily polluted city may receive far less vitamin D-producing radiation than the clear skies suggest.
Clothing and cultural practice. A significant proportion of the Indian population, particularly women, covers most of their skin for cultural or religious reasons. Less exposed skin means less synthesis, regardless of how much sun is available.
Diet fills almost none of the gap. Unlike in many Western countries, Indian dairy products are largely unfortified with vitamin D. The natural dietary sources — fatty fish, egg yolks, liver — are either not consumed or consumed infrequently by a large share of the population, particularly vegetarians. Phytates found in high-fibre Indian diets may further reduce absorption.
The result is a population living under abundant sunshine with almost no effective pathway to adequate vitamin D.
The Honest Complication: Are The Numbers Even Right?
This is the part of the conversation that is rarely had — and it is important.
A 2024 systematic review published in PMC, analysing randomised controlled trials, meta-analyses, and observational studies from 2010 to 2024 specifically in the Indian context, raised a question that challenges the conventional framing: are the vitamin D deficiency thresholds being applied to Indian populations appropriate for Indian biology?
The standard global threshold for sufficiency is 20 ng/mL (50 nmol/L) — below which a person is classified as deficient. This threshold was established largely through research in Western populations. The review found that despite India reporting very high rates of biochemical deficiency using this cut-off, the corresponding disease burden — fractures, rickets, osteomalacia, metabolic complications — appears lower than the numbers would predict if the deficiency were as clinically significant as it appears biochemically.
The authors propose that a threshold of 12 ng/mL may be more physiologically valid for Indian populations, citing differences in sunlight exposure patterns, skin pigmentation, dietary calcium intake, and parathyroid hormone sensitivity. They conclude that mass screening and blanket supplementation in asymptomatic Indians should be discouraged.
This does not mean vitamin D deficiency in India is not a real problem. It means the scale of the problem — and who genuinely needs intervention — may be more nuanced than the headline prevalence figures suggest. Treating a blood test result rather than a patient is a clinical error regardless of what the numbers show.
Who Actually Needs Assessment and Supplementation
The clearest clinical indications for vitamin D testing and supplementation are symptoms and specific risk groups — not routine screening of healthy adults.
Symptoms that warrant testing: Persistent fatigue and low energy without clear cause, bone or muscle pain particularly in the lower back and legs, frequent infections suggesting immune dysfunction, and hair loss or mood changes that do not respond to other explanations. These are non-specific and may have many causes — but vitamin D deficiency is worth excluding when they are present.
Risk groups where proactive assessment is warranted: Elderly individuals, particularly those with limited mobility or who are largely housebound. Children, especially infants who are exclusively breastfed without supplementation. Pregnant and breastfeeding women. People with darker skin tones living in low-sunlight or high-pollution urban environments. Individuals with chronic conditions including kidney or liver disease, which impair the conversion steps. Those with obesity, as vitamin D is fat-soluble and becomes sequestered in adipose tissue.
On supplementation: Vitamin D3 (cholecalciferol) is the recommended form. Dosing should be guided by blood test results and clinical assessment — not self-prescribed based on popular recommendations. Excess vitamin D is toxic. Hypervitaminosis D, while uncommon, causes hypercalcaemia with symptoms including nausea, weakness, and in severe cases kidney damage. Supplementation without testing is a practice the evidence does not support as a population-level default.
The Bottom Line
India’s vitamin D crisis is genuine — but it is not the result of a lack of sunshine. It is the result of a systematic mismatch between the sunlight available and the sunlight that actually reaches human skin in sufficient quantity, at the right time, in the right conditions.
The fix is not simpler sun exposure advice. It requires understanding skin pigmentation, urban reality, air quality, dietary gaps, and the genuine complexity of what it means to get enough of a nutrient that most of the world was supposed to get for free.
And before reaching for a supplement, a conversation with a doctor about actual symptoms and individual risk factors is the more useful starting point.
The sun is there. The biology is not as straightforward as it looks.
📚 References:
Ritu G, Ajay Gupta. Nutrients, 2014.
Aparna P et al. Journal of Family Medicine and Primary Care, 2018.
Arora P et al. ScienceDirect, 2025. (children & adolescents meta-analysis)
Shetty S et al. PubMed Central, 2024. (population-specific thresholds systematic review)
ICRIER Report on Vitamin D & B12 Deficiency in India, 2025.
For assessment of vitamin D status and related metabolic concerns, SDDM Hospital’s Internal Medicine and Preventive Health teams are available at +91-191-2464637 or sddm.hospital.
This article is for general educational purposes and does not constitute medical advice. Please consult a qualified healthcare professional for individualised assessment and guidance.
SDDM Hospital, Jammu Multi-Specialty Care | Internal Medicine | Preventive Health 📍 Channi Himmat, Jammu | 📞 +91-191-2464637 | 🌐 sddm.hospital
