Vitamin D is a fat soluble vitamin. It is the only vitamin that you can synthesize from exposing your skin to sunlight. But, that does not mean expose your skin to sunlight for long time. To synthesize vitamin D from sunlight, you need to expose your skin for less, but at accurate time of day. That time duration of sun exposure varies according to your skin type. Lets discuss all that in detail.

Vitamin D can be synthesized from sun exposure. That is reason why it is called sunshine vitamin. Vitamin D is synthesized in skin by UVB rays of sunlight. UVB rays synthesize vitamin D from cholesterol present in skin. UVB rays provide energy for that synthesises.

Know how to get dose of vitamin D from sunlight-

1) Get vitamin D from sunlight at right time of day-

Vitamin D is synthesized from cholesterol present in skin with help UVB rays of sunlight. But, that does not mean you can sit in any time of day, when sunlight is there.

There is one particular time of day, in which, if you sit in sunlight that lead to synthesises of more vitamin D. Whereas sun exposure at other times of day, lead to synthesises of less vitamin D.

What time of day is that? 

That time of day is midday. At that time of day, if skin is exposed to sunlight, it will synthesize more vitamin D. Whereas skin exposed to sunlight at other times of day synthesize less vitamin D. Not, only that if you expose skin to sunlight after midday, then you will suffer from skin aliments caused by sunlight. For example, sunburns, heat stroke and skin cancer.

2) Sit in sunlight for accurate time duration, according to your skin type-

For vitamin D synthesis, sitting at right time of day in sunlight is important. Same way, sitting for accurate time duration, according to skin type is also important. 

For example- 

• If you have light skin, then you need to sit in sunlight for just 10 to 15 minutes for synthesises of vitamin D.
• Whereas if you have dark skin, then you need to sit for 30 minutes to 3 hours to synthesize vitamin D. For summers time duration is 30 minutes, whereas for winter time duration is 1 to 3 hours.

Why dark skin people need more sun exposure? 

This is because of extra melanin production in dark skinned person. That extra melanin in dark skinned people act as a barrier. This barrier does not let UVB rays of sunlight, to reach to cholesterol present in skin, for vitamin D synthesises. 

3) Sunscreen also act as a barrier in synthesis of vitamin D-

Sunscreen also block UVB rays, just like extra melanin in dark skinned people do. Sunscreen above 30 SPF does not let UVB and UVA rays to reach cholesterol present in skin surface. That results in either decreased or no production of vitamin D from cholesterol in skin. Because of this reason do not wear sunscreen for 30 minutes of sun exposure. You can wear sunscreen after 30 minutes of sun exposure.

4) Time duration for sitting in sunlight, varies according to location of earth-

If you reside in location near to equator of earth, there you won’t get much UVB rays in winter. There sitting for long duration won’t help you as much, as sitting in other areas of earth. The reason for that is UVB rays there are blocked by ozone layer. So, when UVB rays are blocked there, sitting in sunlight exposure won’t synthesize vitamin D. This is because without UVB rays, vitamin D is not synthesized in skin from cholesterol. There only consumption of vitamin D supplements will help. 

5) Some areas of your body synthesize more vitamin D than other areas-

Your head, face and eyes synthesize less vitamin D on sun exposure. Therefore, you can cover them either with cloth or sunscreen while exposing your skin to sunlight. Whereas skin area of rest of body can synthesize more vitamin D on sun exposure.

Best advice-

You can cover your skin with sunscreen after sun exposure of 10-30 minutes, not before that. Time duration of exposure varies from person to person. Therefore, you can stop sun exposure to skin, as soon as burning sensation starts in skin. That is indication of exposure beyond required limit. Do not over expose your skin to sunlight. Because excessive exposure to sunlight has harms. For example-

• Sunburns
• Damage of retina of eye
• Aging of skin
• Freckles and moles in skin
• Heat stroke