Calcium and vitamin D are the two main elements that build and keep bones strong. While calcium is obtained through the diet, vitamin D is a must for its absorption in the intestine.
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Calcium and vitamin D are the two main elements that build and keep bones strong. While calcium is obtained through the diet, vitamin D is a must for its absorption in the intestine. If vitamin D is lacking, bone loss cannot be prevented even with a calcium-rich diet
It’s one of the most frequent health premises — that a quick walk early in the morning, when the sun is out, is sufficient to strengthen your bones and elevate your vitamin D levels. However, experts raise the point that this widely held belief might be false. The timing of your sun exposure is absolutely crucial for calcium absorption and bone health — and according to research, it is actually afternoon sunlight that has the most beneficial effects.
Sunlight and calcium absorption
Calcium and vitamin D are the two main elements that build and keep bones strong. While calcium is obtained through the diet, vitamin D is a must for its absorption in the intestine. If vitamin D is lacking, bone loss cannot be prevented even with a calcium-rich diet.
The skin produces vitamin D when it is exposed to ultraviolet B (UVB) rays from the sun. The vitamin D produced then serves to help with calcium absorption. And these UVB rays needed for the production of vitamin D are at their strongest between 12 p.m. and 3 p.m, when the sun is at its hottest.
Morning sunlight, between 6 a.m. and 7.30 a.m. is mostly made up of UVA rays, which do not stimulate vitamin D production in the skin. Early morning sunlight being enough, therefore, is a myth. To produce vitamin D, the body requires UVB rays, which come from the sun at and after noon.
Therefore, if your intention is to get some sun in the morning to boost vitamin D production, you may not be benefiting.
How much is needed?
The recommendation is, in moderate weather, to expose the arms, face and legs, for 20 to 30 minutes, without sunscreen/SPF lotion, two or three times a week. This is usually enough for the body to get healthy levels of vitamin D. However, long and unprotected exposure to a very hot sun increases the risk of sunburn and, in some cases, skin cancer or other skin damage, so caution is required.
Balance is essential: being in the right type of sunlight for a few minutes is good for the body, but overexposure is not recommended.
Why this matters
Osteoporosis, a condition where the bones become weak and prone to fractures, is often seen in elderly people. In women, it is common after menopause. Of late, however, vitamin D insufficiency and early bone loss has been detected in young women as well. A lack of physical activity, an indoor lifestyle, an unhealthy diet, and barely any exposure to sunlight are mainly responsible for this phenomenon.
In the case of younger adults, lack of vitamin D leads to osteomalacia — a condition that softens and makes the bones fragile. The trend being seen now is of IT workers and urban women who spend most of their times indoors, being affected the most.
What about supplements?
Although vitamin D and calcium supplements are quite easy to obtain, self-medicating is not recommended. Vitamin D alone may not be enough; calcium may also be required. It is best to get tested and then taken supplements, if prescribed, under a doctor’s supervision.
If you have been aiming to get your body its daily dose of sunshine in the morning, it is perhaps time to change plans. One of the easiest and most reliable methods to prevent your bones from giving in to premature wear and tear is to expose yourself briefly and safely to afternoon sunlight, while being on a well-balanced diet and ensuring regular physical exercise.
So if you want your daily dose of sunshine, make sure you get it when the sun is cooperating with you.
Dr. Harsha G N,
Consultant- Orthopaedics, Aster Whitefield Hospital, Bengaluru.