What low vitamin D in winter really looks like
Even in a country bathed in sunshine, vitamin D deficiency is alarmingly common, and winter only exacerbates the problem. Here's why your daily dose might be falling short, and what can help
By Sara Hussain
19 December 2025
Representative image. Instagram.com/mrunalthakur
When winter arrives in India, a familiar fatigue creeps in. You sleep more, wake feeling less rested, and your skin and hair may act up in ways that feel inexplicable. Some of this is seasonal change, but part of it has a biochemical basis: our vitamin D levels tend to fall during the colder months. For a nutrient made mostly through sun exposure, winter presents unique challenges. And in India, where vitamin D deficiency is already widespread.
Vitamin D is often called the sunshine vitamin because it is primarily produced by the body when the skin is exposed to ultraviolet B radiation from sunlight. Despite abundant sunshine in most parts of the country, deficiency is common across age groups and regions. According to research, an estimated 70% to 90% of Indians have suboptimal levels of vitamin D. The reasons are multiple and overlapping.
Nicole Linhares Kedia, a sports nutritionist and integrated health coach, highlights how modern living plays a role. “Urban lifestyles, indoor work, clothing coverage, sunscreen use and pollution reduce vitamin D synthesis even in summer,” she says. For many people, the sun they see on a brief walk or balcony tea break is not the same sun that will meaningfully raise their vitamin D.
With winter’s shorter days and weaker sunlight, the situation changes further. The Earth’s tilt means UVB rays, the ones that trigger vitamin D production in skin, fall at a shallower angle. The result is less effective vitamin synthesis.
Most discussions around low vitamin D in winter focus on weaker sunlight, but in many Indian cities there is a second, more man-made factor at play: pollution.
Dr Varshini Reddy, founder and chief dermatologist at Glow Clinic, explains that air quality affects how much sunlight actually reaches the skin. “UVB is filtered through the atmosphere, and pollution blocks it even further. So despite spending time outdoors, effective synthesis doesn’t occur,” she says.
In dense urban centres, winter often brings smog when fog combines with traffic and industrial emissions. This airborne haze scatters and absorbs UVB rays, leaving less radiation to interact with your skin. Even midday sun exposure may be insufficient if the air is thick with particulate matter.
Vitamin D and skin health
What about sunscreen? It is a common concern, especially for readers focused on skin health. Dr Reddy acknowledges that sunscreens block some UVB, which can reduce vitamin D production. But she is cautious about advising people to skip sun protection. “Managing pigmentation, photo-ageing and inflammatory skin conditions becomes extremely difficult without proper sun protection,” she says. She points out that the potential long-term harm from sun damage can outweigh the benefits of unprotected sun exposure, especially in a climate where UV intensity and smog vary widely.
For many people, especially those with pigmentary conditions or those undergoing active dermatological treatments, strict sun avoidance or partial coverage is a necessary part of their routine. In such cases, relying on sunlight alone to maintain vitamin D levels is neither practical nor safe.
“Conditions like eczema and psoriasis worsen during winter, as vitamin D supports skin barrier proteins that help retain moisture and reduce inflammation,” she says. She also points out that vitamin D plays a role in regulating skin growth and inflammation, meaning dryness, flaking and scaling can become more prominent in winter.
Hair fall is another common complaint. Vitamin D interacts with hair follicle cycling, and some forms of hair shedding can be exacerbated when levels drop. Seasonal pattern hair shedding in the winter months may reflect this interplay.
Kedia also notes the effect on broader wellbeing. “Limited sun exposure affects your circadian rhythm and may lower melatonin levels, impacting sleep quality,” she says. That explains why sluggishness, poor sleep, and low energy often cluster together as the days get shorter.
Can diet and supplements bridge the gap?Vitamin D is present in a few foods. Natural sources include egg yolks, fatty fish such as salmon, liver, and mushrooms exposed to sunlight. In India, fortified foods like milk, curd and some cereals contribute more reliably than natural sources alone.
“Vitamin D is difficult to obtain from food alone, which makes adequacy challenging through diet alone,” Kedia says. She stresses that diet can support but not fully replace sun exposure and supplementation when needed.
Absorption is not as simple as swallowing a pill. “Vitamin D3 is fat-soluble, so it should always be taken with a meal containing healthy fats,” Kedia explains. That means taking supplements alongside foods like nuts, ghee, eggs or avocado to improve absorption. She also emphasises the importance of gut health and magnesium, both of which influence how well vitamin D is utilised by the body. Addressing magnesium or chronic gut issues can improve outcomes for people who supplement but see little change in blood levels.
Crucially, she cautions against blind supplementation. “Excess vitamin D can cause toxicity, so a blood test is essential before starting or modifying any supplementation,” she says. This reflects a growing consensus among clinicians that personalised dosing, based on measured levels, is safer and more effective than generic intake.
A practical approach for the colder months
If you suspect that you have low vitamin D in winter, a midday walk with arms and legs safely uncovered can help when pollution levels allow, but this alone is often insufficient. Prioritising foods with vitamin D, pairing supplements with healthy fats, and addressing gut health and magnesium status are also part of a comprehensive strategy.
Understanding why winter affects vitamin D, especially in polluted urban conditions, helps demystify symptoms that many dismiss as “just winter fatigue.” With the right mix of science and practical steps, you can manage your levels more effectively and support your overall health throughout the year.
Disclaimer: This article is for educational purposes only. Please consult your healthcare provider to find a treatment plan that works best for your needs. |
