Why winter sunlight often fails to prevent vitamin D deficiency in Indians

Vitamin D is essential for bone health, immunity, and overall wellbeing. From a young age, we are told that sunlight is the best source of this vitamin. However, many Indians remain deficient in vitamin D during winter, even if they spend time outdoors. Experts explain why winter sunlight alone often fails to maintain adequate vitamin D levels and why supplementation is necessary for many people.

During winter, the sun appears lower in the sky, and the atmosphere blocks a significant portion of UVB rays, which are crucial for vitamin D production in the skin. Dr Monika Sharma, Senior Consultant in Endocrinology at Aakash Healthcare, explains, “The winter sun in India creates a deceptive sense of security. People assume that daily sunlight is enough to maintain vitamin D levels, but the seasonal decline in UVB strength makes that almost impossible.” Even if people spend long hours outdoors, their skin does not receive enough UVB exposure to produce sufficient vitamin D.

Another factor is skin color. Melanin, the pigment responsible for darker skin, naturally reduces the skin’s ability to make vitamin D. Dr Sharma notes, “People with darker skin need longer sun exposure to generate the same amount of vitamin D as lighter-skinned individuals. This becomes especially difficult in winter when UVB rays are already weak.” This means that even outdoors exposure for a short time may not be effective for many Indians.

Urban lifestyle, clothing, and diet worsen deficiency

Urban living further reduces meaningful sunlight exposure. Most people spend their days indoors, commuting in cars, or staying in shaded areas. Even outdoor activities in cities may not help, because air pollution absorbs and scatters UVB rays. “Pollution can significantly reduce the effectiveness of sunlight,” says Dr Sharma. This is why people living in cities often remain deficient despite apparent exposure to sunlight.

Clothing habits during winter also limit vitamin D production. Thick sweaters, coats, and scarves cover most of the skin, leaving little area for sunlight to reach. Dr Sharma adds, “Sunlight needs exposed skin to work, not just being outdoors. Winter clothing compounds the problem.” Cultural and lifestyle habits, like avoiding early morning or late afternoon sun, further limit the potential for vitamin D synthesis.

ALSO READ: 150 years of Vande Mataram: BJP, Congress clash over missing stanzas

ALSO READ: Government expands crackdown by banning 23 organisations under UAPA in five years

Diet alone is not enough to fill the gap. Traditional Indian diets are naturally low in vitamin D, and fortified foods are not consistently available across the country. “Even with a healthy diet, most Indians cannot rely solely on food to meet their vitamin D needs during winter,” explains Dr Sharma. This makes supplementation a safe and reliable solution, especially for people already deficient or at high risk, such as older adults, people with obesity, and those with chronic illnesses.

Experts recommend periodic testing to monitor vitamin D levels. Personalized supplementation can help maintain optimal levels, even when natural sunlight is insufficient. In addition, small lifestyle adjustments, such as spending time in the sun during peak hours and using open areas rather than shaded spaces, can improve vitamin D production. However, for many urban Indians, supplementation remains the most practical and effective solution during the colder months.

Winter sunlight may seem sufficient, but the combination of reduced UVB rays, darker skin tones, air pollution, indoor lifestyles, clothing habits, and low dietary intake explains why vitamin D deficiency persists. Dr Sharma emphasises, “Supplementation is not just a precaution. For many, it is the only reliable way to maintain healthy levels of vitamin D through the winter season.”

In conclusion, while sunlight is an important source of vitamin D, winter in India brings multiple challenges that make natural production difficult for most people. Awareness about these factors, combined with regular monitoring and supplementation, can help prevent deficiency. Maintaining adequate vitamin D is crucial not just for bone health but also for overall immunity, energy levels, and long-term wellbeing. By understanding the limits of winter sunlight, individuals can take proactive steps to stay healthy throughout the season.