Sunshine & SKELETONS

Q My sister is so worried about sun exposure that she doesn’t let her children play outdoors during the day. I’ve heard that children can develop weak bones if they don’t get enough vitamin D from the sun. What do you recommend?

A DR MARETHA COMBRINK ANSWERS: Vitamin D helps your body absorb calcium to promote bone growth. The general public as well as some medical professionals share the common belief that sun exposure is the main source of vitamin D production in the human body. It has been suggested that sun exposure for approximately 15 to 30 minutes two to three times per week is sufficient to produce the required amount of vitamin D in the skin. However, there is little to no factual proof of this. Several other important aspects related to sunlight exposure (like photo-ageing, predisposition to skin cancer, cataracts, retinal injuries and autoimmune diseases) have mostly been ignored. Recent studies on vitamin D status have suggested that deficient levels are probably a reflection of dietary deficiency rather than lack of exposure to sunlight.

The amount of sun exposure required to produce adequate amounts of vitamin D depends on the type of skin, with darker-skinned people requiring almost 10 times more sun exposure than fairskinned people. Other factors to consider

include latitude of residence, season, time of day, cloud cover and surface reflectivity. Therefore, the use of deliberate sun exposure to maintain vitamin D is not recommended. Just one episode of blistering sunburn during childhood or adolescence doubles a person’s chance of developing melanoma later in life. Some studies indicate that basal cell carcinoma may also be triggered by sun exposure. Infants under the age of 6 months should not be exposed to sunlight. Special care should be taken from 10am until 3pm when the ultraviolet (UV) radiation of the sun is at its most intense. Sun protection for children should include sunscreen, avoidance of sun exposure during peak times and the use of appropriate clothing, hats and sunglasses.

Children under the age of 12 months require an estimated 400IU of vitamin D per day, and children older than a year roughly 600IU per day. Apart from supplementation, natural sources of vitamin D include egg, salmon, sardines, tuna, mackerel and shiitake mushrooms. Fortified foods include cereal, orange juice, yogurt and margarine. ●