Question of the Week
June 14, 2004


Summer is here.
We have all been warned about the dangers of skin cancer and too much sun, but the sun is not all bad!
How could the sun possibly be good for a person's health? Even help FIGHT cancer?

"How can sunlight also protect against cancer? The answer lies in a vitamin that may play a role in controlling the production of cells - vitamin D. Vitamin D is manufactured in the skin when it is exposed to sunlight and it is this vitamin that may have a protective effect against certain cancers by preventing the overproduction of cells."

Vitamin D: "...this vitamin that may have a protective effect against certain cancers..."

In addition, "A diet rich in vitamin D may reduce the risk of developing rheumatoid arthritis and multiple sclerosis. Two studies involving more than 200,000 American women have highlighted the vitamin's benefits....Both conditions are thought to occur when the body's immune system turns against itself. Vitamin D may work by calming overactive immune cells, speculates Kenneth Saag from the University of Alabama, Birmingham, who led the arthritis study.... Vitamin D is a steroid hormone that helps the body absorb and retain calcium. Too much can be toxic, while too little causes brittle bones."

Yes, Vitamin D. Before you get too excited and trade your sun screen for hours of unprotected sun exposure:

"Vitamin D is called the 'sunshine vitamin' because it is formed in the skin by the action of ultraviolet rays from the sun. For fair skinned individuals, 15 minutes of sunlight will produce enough Vitamin D to last for several days, even when wearing light clothing. However, it takes 3 hours or more for this to happen with dark-skinned people."

Times ranging from 15 minutes to 3 hours? (Please note that these times are not recommended for everyday. Just a few times a week is plenty.) Why such a broad spectrum?

"Different people have different amounts of melanin in their skin. Those with a Northern European background tend to have less melanin and be rather pale, whereas people with dark brown or black skin, like many people from Africa, have more. Based on these differences, dermatologists have come up with six skin types, ranging
from a Type I (fair skin, blonde or red hair, and always burns in the sun) to a Type VI (black skin and usually
doesn't get sunburned). People who are a Type V or VI have more natural protection against the sun than those who are a Type I or II, but that doesn't mean they should ignore warnings about sun exposure."

Even those with Type V or VI need to be careful. Three or more hours of sun exposure is needed if there are no other sources of Vitamin D (like from one's diet). Even so, this is the total amount of time needed for several days worth of Vitamin D. A total of about forty-five minutes a day in the sun: walking to and from school, waiting for the school bus, driving with the windows rolled down, walking between classes, and the list goes on. It is not hard to get 3 hours of sun over the course of a few days. For those who need only fifteen minutes, it seems as though it would be difficult not to get more.

"But workaholism and legitimate fear of skin cancer -- sunscreen blocks D production -- limit how much Americans produce even in summer. Winter sunlight is not intense enough at most U.S. latitudes to produce any, Holick says."

So how much is enough? Too much?

"Holick and others argue that instead of the 200 to 600 international units a day that current recommendations suggest, most people should be getting at least 1,000 units a day. In a controversial new book, 'The UV Advantage,' Holick recommends exposing the hands, face, arms and legs to the sun for five to 15 minutes a day a few days a week, which he says would be enough to generate that amount without increasing the risk for skin cancer. Many people are not getting even that amount of sun exposure on a regular basis, Holick and others say. 'There's no question that chronic, excessive exposure to sunlight and sunburning incidents markedly increases your risk for skin cancer. But there's little evidence out there that if you practice safe
sun exposure, it would increase your risk for skin cancer or wrinkling,' Holick said."

Yes, wrinkles.

"To get a good idea of the effects of sunlight, look at your parents' skin and see how different it is from yours. Much of that difference is due to sun exposure and only a small part is due to the fact that your folks are actually older than you are. In the worst-case scenario, too much sun can cause skin cancer, lead to problems with your eyes, or weaken your immune system, making it harder for you to fight off diseases. Skin cancer is epidemic in the United States. Although the numbers of new cases of many other types of cancer are falling or leveling off, melanoma, the most serious (and most frequently fatal) type of skin cancer, is the fastest-growing type of tumor in the United States in terms of new cases. In fact, dermatologists are seeing patients in their twenties with skin cancer these days - in the past, skin cancer mostly affected people in
their fifties or older."

The need is still there to be safe in the sun.

"Although overall, men are more likely than women to develop skin cancer, women under the age of 40 comprise the fastest growing group of skin cancer patients."

There is such a thing as too much of a good thing.

"There is a high health risk associated with consuming too much vitamin D. Vitamin D toxicity can cause nausea,
vomiting, poor appetite, constipation, weakness, and weight loss. It can also raise blood levels of calcium, causing mental status changes such as confusion. High blood levels of calcium also can cause heart rhythm abnormalities. Calcinosis, the deposition of calcium and phosphate in soft tissues like the kidney can be caused by vitamin D toxicity. Consuming too much vitamin D through diet alone is not likely unless you routinely consume large amounts of cod liver oil. It is much more likely to occur from high intakes of vitamin D in supplements. The Food and Nutrition Board of the Institute of Medicine considers an intake of 25 mcg (1,000 IU) for infants up to 12 months of age and 50 mcg (2,000 IU) for children, adults, pregnant, and lactating women to be the tolerable upper intake level (UL). A daily intake above the UL increases the risk of
adverse health effects and is not advised.

While "Multivitamin supplements commonly provide 200-400 IU of vitamin D daily. He says a light-skinned person wearing a swimsuit at the beach will have absorbed about 20,000 IU of vitamin D in the time it takes their skin to get lightly pink...'The trick is getting just enough sun to satisfy your body's vitamin D requirement, without damaging the skin,' he says. 'It is difficult to believe that this kind of limited exposure significantly increases a person's risk of skin cancer.'"

Questions of the Week:
Think about the life you lead, what type of skin you have, and where you live. What is a healthy amount of sunlight for you? How does this differ from what might be a healthy amount for someone else? What do you need to do in order to work this healthy balance into your busy life?

Please email me with any ideas or suggestions.
Note: Due to increasing amounts of SPAM sent to this account, please include "QOW" in the subject line when sending me email.

I look forward to reading what you have to say.

Health Community Coordinator
Access Excellence @ the National Health Museum

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