Winter light can’t meet vitamin D needs
Weak winter sunlight fails to provide enough vitamin D, experts warn
India gets plenty of sunlight, but vitamin D deficiency is still very common, especially in cities. Many people believe that simply standing in the sun is enough to meet their vitamin D needs, but this is not true. Sunlight is important for making vitamin D, but exposure to sunlight and the actual vitamin D your body produces are not the same thing.
According to Dr Pranav Ghody, Consultant Endocrinologist at Wockhardt Hospitals in Mumbai, winter makes it even harder to maintain good vitamin D levels. Several factors, including the weather, lifestyle, and environmental conditions, reduce the body’s ability to make enough vitamin D, even on sunny days.
Vitamin D is produced in the skin when UVB rays from the sun reach it. The body cannot make vitamin D without this specific type of sunlight. Dr Ghody explains: “Sunlight alone doesn’t guarantee enough vitamin D. What really matters is UVB exposure, which depends on the angle of the sun, the time of day, skin type, and pollution levels.”
Most urban Indians face challenges in getting enough UVB exposure. Work hours, indoor lifestyles, and clothing limit skin exposure during peak UVB hours, which are generally between 10 am and 2 pm. Many people stay indoors during this time, meaning the skin does not get the rays it needs to make vitamin D.
Why winter sun is weaker and what affects vitamin D production
Winter sunlight may feel warm, but it provides much less UVB radiation. The sun sits lower in the sky, and more UVB rays are filtered by the atmosphere before reaching the ground. This makes it difficult for the body to produce enough vitamin D naturally during winter.
Two other issues make the situation worse. First, people wear more clothing during colder months, covering most of the skin. Second, pollution is often higher in winter, especially in big cities, and pollution blocks or scatters UVB rays. Even spending 20–30 minutes outside may not generate sufficient vitamin D during this time.
Skin tone also affects how much vitamin D your body can make. Melanin, the pigment that gives skin its color, acts as a natural sunscreen. People with medium or dark skin need much more sun exposure to produce the same vitamin D as people with fair skin. During winter, when UVB is already weak, this makes it especially hard for darker-skinned individuals, indoor workers, or people living in polluted areas to get enough vitamin D from sunlight alone.
For mild deficiency, sunlight can help, but in most urban settings, winter sun alone is rarely enough. Dietary sources like fortified milk, eggs, mushrooms, and fish can support vitamin D levels, but they provide only a small portion of daily requirements. For people who already have low vitamin D, supplements may be necessary. These should be taken under medical supervision because too much vitamin D can be harmful.
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Dr Ghody recommends simple strategies to maintain vitamin D in winter:
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Get brief sun exposure between 10 am and 2 pm on clear days.
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Include vitamin D-rich and fortified foods in your diet.
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Discuss supplements with a doctor if you have a history of deficiency.
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Monitor for signs of low vitamin D, such as fatigue, muscle weakness, bone pain, or low immunity.
In winter, vitamin D naturally drops. Planning is important to prevent problems caused by deficiency. Sunlight is everywhere in India, but usable vitamin D is not. Winter sun is weaker, pollution is higher, and daily habits like staying indoors or wearing covered clothing during peak UVB hours reduce vitamin D production.
The key is not to chase sunlight obsessively, but to adopt a smart strategy. Combining brief sun exposure, a vitamin D-friendly diet, and, if necessary, medical supplementation ensures your levels stay healthy. Maintaining vitamin D is not about more sun, but about using sunlight effectively and supporting your body in other ways.
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