Despite abundant sunlight year-round, South India leads the nation with more than 50% of its population showing vitamin D deficiency highlighting the surprising paradox that geography alone doesn’t guarantee nutritional wellness.
Glimpse:
A comprehensive analysis of over 2.2 million vitamin D tests from across India revealed that South India had the highest deficiency rate at 51.6% with states like Kerala, Tamil Nadu and Puducherry exceeding the 50% mark. Factors such as indoor lifestyles, darker skin pigment, limited sun exposure and low dietary/fortified vitamin D intake combine to thwart vitamin D synthesis even under bright skies.
It may seem counter-intuitive, but the sunniest regions of India are registering some of the highest rates of vitamin D deficiency. A large-scale study by Metropolis Healthcare Limited, based on more than 2.2 million serum 25-hydroxyvitamin D tests collected between 2019 and early 2025, found a national deficiency rate of 46.5%, while another 26% had insufficient levels. Regionally, South India stood out with the highest deficiency proportion at 51.6%.
This trend is particularly stark given the expectation that ample UVB exposure from sunlight should support adequate vitamin D synthesis in tropical regions. Multiple smaller studies reinforce this finding: for example, one study among antenatal women in Chennai found about 62% had levels < 20 ng/mL.
Key drivers behind this paradox include:
Indoor lifestyles: Urbanisation and office-based jobs limit sun exposure.
Skin pigmentation: Higher melanin levels in darker skin reduce vitamin D production from sun exposure.
Clothing/cultural practices: Extensive body coverage and avoidance of direct sun further reduce UVB exposure.
Limited dietary/fortified sources: Many Indian diets lack vitamin D-rich foods and food-fortification is still slow.
Sedentary or shaded lives: Time outdoors is limited for many, meaning actual UVB exposure may be minimal despite sunshine.
The health implications are broad: low vitamin D is linked to reduced bone mineralisation, osteomalacia, and may contribute to generalised muscle weakness, fatigue and possibly wider metabolic and immune consequences. Experts argue that recognising the deficiency as a public-health issue (rather than an individual issue) is crucial, especially in India’s southern states where the numbers are alarming.
“The irony is striking: despite abundant sunlight, over half of individuals in South India still show deficiency. It’s a wake-up call that sun alone doesn’t guarantee vitamin D sufficiency.”
By
HB Team
