Even though India is blessed with bright sunshine throughout the year in most places, the prevalence of vitamin D deficiency is rather common. One of the reasons for this is that timing, duration, and skin exposure to the sun all matter in order to produce enough vitamin D in the body.
Table of Contents
- Reason for Vitamin D Deficiency Despite Sunlight in India
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Best Time of the Day for Synthesis of Vitamin D
- Sun Exposure Duration Required for Sufficient Vitamin D
- Factors Influencing Vitamin D Synthesis in Indian Conditions
- Regional and Seasonal Variations in India
- Striking a Balance Between Vitamin D and Skin Protection
- When Sunlight Alone Isn't Enough
- Key Takeaways
- Conclusion
- FAQs
Reason for Vitamin D Deficiency Despite Sunlight in India
These are some of the reasons for the apparently contradictory phenomenon:
- Coverage by clothes, which inhibits skin exposure to UVB radiation required for vitamin D production
- Indoor living conditions, especially in cities where people have to work for long periods inside
- Usage of sunscreen, although important for skin health but hinders the entry of UVB radiation
- Presence of air pollution, which can block a certain amount of UVB radiation in highly polluted cities
- Darker skin color, which is predominant among Indians and necessitates greater exposure to the sun in order to generate similar levels of vitamin D as people having lighter skin, due to more melanin concentration
- Exposure timing to the sun, as many individuals get sun exposure at times that are less effective for vitamin D production
Best Time of the Day for Synthesis of Vitamin D
The best possible period for synthesis of vitamin D, for most parts of India, is typically from 11 a.m. to 1 p.m. when the sun is at its highest point and the UVB rays, which are responsible for synthesis of vitamin D in the skin, are most intense. This might be a little contradictory, as people usually avoid the sun during these hours owing to the hot climate and higher UV rays, but this period has the highest concentration of UVB rays in relation to the exposure time required.
The earlier and later periods of the day, despite being more comfortable, have lower concentrations of UVB rays in comparison to the UVA rays.
Sun Exposure Duration Required for Sufficient Vitamin D
In case of a moderate skin type, exposure of limbs or back without any sunscreen for about 15-30 minutes several times in a week from 11AM-1PM is usually considered enough for producing sufficient quantities of vitamin D although it depends upon the following factors:
- Skin colouring (the more tanned the skin, the more exposure will be required)
- Amount of skin exposed
- Latitude in India
- Season
- The amount of air pollution at a particular place
Factors Influencing Vitamin D Synthesis in Indian Conditions
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Skin tone - Due to higher levels of melanin in darker skin, this skin acts as an inherent sunscreen which implies that darker individuals need more time of sun exposure to produce the same quantity of vitamin D as a person with light skin.
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Latitude - The northern regions in India, like Kashmir or Himachal Pradesh, receive less UVB rays as compared to other parts of India, especially in the winter season.
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Urban air pollution - The level of urban pollution may reduce UVB penetration in some cities of India.
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Altitude - Locations located at a high altitude receive more UVB rays because the atmosphere is thinner there.
Regional and Seasonal Variations in India
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South India and coastal India (Kerala, Tamil Nadu, and coast of Karnataka) regions usually have fairly consistent levels of year-round availability of UVB due to proximity to the equator.
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North India regions (Delhi, Punjab, and Kashmir) tend to show significant variation of UVB depending on seasons, especially showing weak availability in winter months even at noon.
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The monsoon season, covering most of India, shows reduced direct sun availability due to clouds; this should be considered for supplementation during the season.
Striking a Balance Between Vitamin D and Skin Protection
Although the window of 11 AM to 1 PM is the best time to synthesize vitamin D from sun, this time period is also risky in terms of getting sunburn and skin cancer. For this reason:
- Have short sessions of sun exposure (15-30 minutes) rather than prolonged ones.
- Sun expose smaller parts of your body (legs and arms) rather than whole body.
- Do not use this method if you have a history of skin cancer or photosensitivity or have been medically advised to avoid sun exposure.
When Sunlight Alone Isn't Enough
As a result of the delicate balance required between sufficient production of vitamin D and skin protection, along with various lifestyle factors that prevent regular midday sun exposure, food sources and supplements may be a useful complement in the case of:
- Individuals who have no or limited exposure to the outdoors due to their work hours
Residents of the north during winters
- People with dark skin requiring much more exposure time
- Deficient individuals as determined by blood test, where supplement intake is needed to address the deficiency.
Key Takeaways
- The time period of 11 AM to 1 PM represents the best option for exposure to UVB in order to produce vitamin D in most areas of India, although midday sun exposure is avoided by many Indians.
- Dark skin, pollution in the air, and lack of outdoor exposure lead to a high rate of deficiency in spite of plentiful sunshine.
- 15-30 minutes a few days a week is sufficient in many cases, although individual requirements may vary widely.
Conclusion
While achieving sufficient intake of vitamin D through sunlight in India is absolutely doable, it will require more strategic timing than what many may think - that nice, comfortable early morning or late afternoon sun that people usually prefer is much less effective than taking short sunbath during midday hours. And for many people, especially with restricted opportunities to spend time outdoors or who have risk factors for being deficient, a combination of proper sunlight intake and dietary intake is the best way to get enough vitamin D.
