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Thursday, April 05, 2007

Am I exposing myself to cancer risk?

"Dear Gary
I live in Mississippi, age is 56 and I am very active. If I am forced to be out doors between 1000-1400 for any length of time, I use sunscreen.
Outside these hours, I will not use sunscreen. However, before and after these hours, I like to go out twice a week for 30 minutes, to expose as much skin to the sunlight as I can. I usually only do this when the weather is warmer.
During the cooler months, just my face and hands get the sunlight, whenever I just happen to be outside.
Considering the above, any problems with overexposure, cancer risks?"
Gary Moller comments:The purpose of getting daily sunlight is twofold:

  1. To ensure vitamin D levels are at optimum for health and fitness
  2. To set the body clock which is again essential for health
You first need to establish your current status:
  1. Determine vitamin D by a simple blood test through your Dr and then compare your results with recommendations for optimum health by going here.
  2. Complete this simple assessment to determine how well your circadian cyle is synchronised and abide by the guidelines for exposure to full spectrum light.
How much sun you require for optimum vitamin D is determined by:
  1. How deficient you are, if at all
  2. Your skin type
  3. Where you live
I have seen no evidence that incidental exposure of the face and hands or even the arms is sufficent to maintain healthy D levels. Read this. To boost vitamin D levels you need to expose large expanses of skin to the sun. If skin has been damaged by repeated sunburn over the years then it is less efficient at producing vitamin D.
If you are deficient, as determined by a blood test, then you need to expose your skin to sunlight 2-4 times a week and only for suffient to get the slightest pinking of the skin. No burning! Sunscreen prevents production of vitamin D and should only be applied to damaged or sensitive parts of the skin, or better still, covered over.
If you are highly prone to freckling or very fair then you must take great care and may only require 5 minutes of full body exposure to the midday sun. If you are olive skinned then you may require 10-15 minutes. If you have very dark skin, your needs may be 40 or 50 minutes - get the idea?
If you over-expose and get a dark tan then the time you need to spend in the sun becomes longer, so excessive tanning is counter-productive and potentially damaging to the skin, so stick to the minimalist approach according to your skin type.
A big factor is where you live, time of day and the season of course! If you live in New Zealand, then your exposure needs are less due to the Ozone Hole over our country allowing in more UV radiation which is the light that produces vitamin D but also causes skin cancer. If you live in a place with high air pollution levels, your exposure time will have to be longer since the pollution filters out the UV. The best time for exposure is midday because that is the time of highest UV. Set an egg timer for 5 minutes and then roll over for the other side and then cover up. Take note of how your skin is several hours later and increase or decrease the exposure accordingly.
I have discussed the matter of skin cancer with a skin specialist and can pass on the following. First of all, if you are olive or dark-skinned like a Polynesian or African, then your statistical odds of developing sun-caused skin cancer are very low, to the point of being negligible. If you are fair, red-headed, and/or freckly then you are at high risk and must take great care not to suffer sunburn.
The best time to measure D levels by a blood test is during Spring and then with the onset of Autumn. These will give your seasonal highs and lows and will show how effective you have been over summer at building your stores of D. I measured my levels in Spring and had a dissapointing 68nmol. I am due to have the test repeated now it is almost Autumn and I expect it be be much higher. Got the idea? Over winter, you work on a D rich diet to maintain the body's vitamin D stores as best you can then repeat the test next Spring.
If you develop a cancer like melanoma then you must take measures to reduce the possibility of developing secondary cancers within the body. One of your best protections against secondary cancer is high vitamin D. So you know what I will be doing if I develop a melanoma - Yes! I will be getting a blood test to assess my current D status.

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