Vitamin D is produced naturally in our skin when exposed to the rays of the sun. It has an important role in taking the calcium from the food we eat into the body. Calcium is necessary to make our bones strong, our muscles contract, and also helps our body fight against infections, among other things.
Children and adults who have little exposure to sun or are not consuming enough vitamin D and calcium begin to remove calcium from their bones to make up for the deficit. If this goes on for a long time there can be pain in the bones and they become very weak, meaning that they can become fractured easily.
We could get enough vitamin D from the sun, but during winter the days become short and often we are on our way to school or work when it is still dark and return home when the sun has already set. An increased awareness of the effect of sunlight on ageing and skin cancer has made us use umbrellas, hats, and sunscreen on sunny days. So the rays that would have touched our skin are stopped by these physical or chemical barriers before they are able to create vitamin D in our skin.
An additional factor is air pollution, it creates a shield which decreases the amount of sun that reaches our skin. Also, on polluted days we tend to choose indoor activities to avoid breathing “outdoor” air.  On the good air days we should make a special effort to walk or play outdoors in the early morning or late afternoon sun because exercise, sunlight.
Vitamin D is found in salmon, tuna, and vitamin D enriched juices or dairy products. Make sure to check and confirm if products contain vitamin D before thinking they may be supplying your daily needs.
How do I know if I need to take a vitamin D supplement?
It is important for everyone to take vitamin D daily during the winter season, sometimes all year round. D3 vitamin D has the best absorption, and since it is a fat-soluble vitamin it is best if you take it in oil form after a meal. This can be in drops for children or soft gel capsules for adults.
There are special conditions when you need higher doses of vitamin D. For example if you are pregnant or breastfeeding, if you are growing or have asthma, if you have bone pain, feel very tired all the time, or have had fractures that were hard to explain.  You may have vitamin D deficiency and you should check your vitamin D levels to see what daily dose is appropriate for you.
On the other hand a few people who suffer from kidney stones or have special health problems may have too much calcium in their body and should check their calcium and vitamin D levels before they begin taking the supplement.

Need more info?
Dr. Dorothy Dexter is a family medicine physician at Beijing United Family Hospital. She has several years of clinical experience, and speaks English and Spanish. Contact her at dorothy.dexter@ufh.com.cn

This article originally appeared on page 19  of the November/ December issue of beijingkids magazine. Click here for your free online copy. To find out how you can obtain a hard copy, contact distribution@truerun.com.

“The risk of children suffering from flu can be halved if they take vitamin D, doctors in Japan have found. The finding has implications for flu epidemics since vitamin D, which is naturally produced by the human body when exposed to direct sunlight, has no significant side effects, costs little and can be several times more effective than anti-viral drugs or vaccine.

“Only one in ten children, aged six to 15 years, taking the sunshine vitamin in a clinical trial came down with flu compared with one in five given a dummy tablet. Mitsuyoshi Urashima, the Japanese doctor who led the trial, told The Times that vitamin D was more effective than vaccines in preventing flu.

Vitamin D was found to be even more effective when the comparison left out children who were already given extra vitamin D by their parents, outside the trial. Taking the sunshine vitamin was then shown to reduce the risk of flu to a third of what it would otherwise be.”

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