Let the Sun Shine?

admin | 10:27 am | March 8, 2010 | Uncategorized

A summer holiday invariably involves some basking in the sunlight, but the warnings regarding the dangers of UVA and UVB radiation have made us a little more cautious about how much time we spend exposing our sensitive skins to the sun. Although the sun’s radiation can cause skin cancer, a lack of sunshine can contribute to certain cancers too. So do we bask or do we cover up? The answer is a little bit of both.

According to scientists at SUNARC (Sunlight, Nutrition and Health Research Center) in San Francisco, California, we may be doing ourselves more harm then good by staying out of the sun. We have always known that the sun helps us produce a vital nutrient- vitamin D, but until more recently we did not know just how important vitamin D might be to our health, especially in the prevention of cancer.

According to a position paper presented by SUNARC in April 2008, Vitamin D associated cancers include colon, gastric, rectal, pancreatic, bladder, kidney, prostate and breast. A study published in the June 2007 American Journal of Clinical Nutrition looked at vitamin D, calcium and cancer risk in post-menopausal women in Nebraska in the U.S. They found that all-cancer incident for women over age 55 was reduced by 77% in women who received a supplement containing calcium and vitamin D compared to a placebo. An epidemiological study conducted on Ontario Canada Considering 759 cases and 1,135 controls from a case-control study; found that higher intakes of vitamin D were associated with a reduced risk of both estrogen receptor and progesterone receptor breast cancers.

A Harvard cohort study in the 2006 April Journal of the National Cancer Institute, found inverse correlations with vitamin D intake (from sunlight and food) for many cancers including colon and rectal and estimated from the findings that male cancer death rates could be reduced by 29% for an intake of 1500IU of vitamin D per day.

So, if vitamin D can prevent cancer, should we be enjoying the sun guilt-free? Definitely not! In order to synthesise enough vitamin D, we only really need 20-30 minutes of direct skin contact with the sun, without SPF (Sun Protection Factor inhibits vitamin D absorption). So lying in your bikini for 5 hours getting a tan, is far exceeding what you need for your daily dose of vitamin D, and could be putting you at risk for skin cancer. The amount of vitamin D we get from the sun is self-regulating. According to CANSA (Cancer Association of South Africa), the amount of sun needed to make enough vitamin D is always less than the high amounts that cause tanning or sunburn. You don’t need to spend hours in the sun to feel the benefits of sunlight, explains CANSA. In fact, extra time in the sun doesn’t mean you keep on producing more vitamin D. When your body has healthy levels of the vitamin any excess is just broken down

The main reason we have been urged by medical professionals to stay out of the sun, is because of the risk of skin cancer (basal cell carcinomas, squamous cell carcinomas and melanomas). Melanomas tend to be the more dangerous type as they can more easily metastasise (spread). According to CANSA, sunburn doubles the risk of skin cancer. The back is more prone to melanoma in males while the lower legs are a more common site in females. Certain skin types are more prone to melanoma. Skin is graded 1 through 6 depending on the colour. Type 1 skin is very light, burns easily and never tans. This type of skin is most prone to melanoma. Type 6 skin, which is very dark and never burns, does not usually require any sunscreens and skin cancers due to sun damage are unlikely. The more tanned you are too, the more protected you are from skin cancer. So if a tan is what you are after, gradually and slowly is the way to go.

We can also get Vitamin D from food, although sources are rare. The only other significant natural source of vitamin D is fatty fish (like salmon, mackerel, pilchards and sardines) and fish oils. Most margarines and dairy products are now fortified with Vitamin D. Vitamin D supplements are also a consideration for people who are unable to get maximum UVB exposure or who do not get enough vitamin D from dietary sources.

(a version of this post also appeared in Business Day Health News)