Yep I’m at the Vitamin D thingy again….but I cannot help myself Vitamin D has been linked to so many diseases including MS and despite being a sun junky since being diagnosed with MS, I am still at the lower edge of normal so how must the rest of the world be.
We think in Australia if we lead an outdoor lifestyle that we are getting enough sun but actually no and our incidence of lack of vitamin D and all its negative health effects are higher than some of the northern hemisphere countries.
Vitamin D can only be made from UVB which is only available for 11am – 1 pm from Nov to Feb in Australia. So unless you are out in this time you get ZERO healthy sun ie UVB. In March-October, i.e. now, they think the Vitamin D window is only 30 mins at midday. In Australia we have extra high UVA all day because our ozone is thicker. Ozone kills UVB. UVB is being blocked by sunscreen.
Melanoma is created from UVA only which does not burn the skin and is in the sun’s rays present all day. UVA cannot be blocked by sunscreen. UVA is only blocked by heavy (thick or dark) clothing and zinc cream.
There is a rule of thumb for healthy amounts of sun that says ‘10 minutes naked at midday’. So unless you are totally freaking out the locals you are getting no Vitamin D except for the 10 min walk to buy a sandwich at midday. They say alternatively 30 minutes of sun on arms and legs exposed at midday is enough. So buy the sandwich and sit in the sun to eat it. But if you are one of those extreme northern hemisphere redheads take your bikini with you as 30 mins may cause burning. The thing about vitamin D conversion is it takes both skin mass (cubic centimetres) and time so the more skin, the less time.
The signal that your skin is converting to vitamin D is: it is getting pink. So if you never get pink you are not converting to D. If you already have a proper tan it takes longer to start pinking and the conversion takes longer to get enough vitamin D, so back to the bikini. I get it now why solariums are still popular in Australian cities.
UVB creates tanning (and so sunburn) and UVA does not.
Tans prevent melanoma. Tans also kill skin elasticity and cause wrinkles (unattractive but maybe better than depression or MS)
UVA heats the skin and UVB does not.
So when you are out in UVA you are feeling the heat on your skin and you think you are burning. Of course the hottest time of everyday is the middle of the day when you have the very small window of vitamin D production so that is when most people are likely to put on sunscreen or stay indoors or in the shade.
There are few other interesting correlations: non elastic skin suffers with lower rates of melanoma, tanning kills elasticity, so areas that never get tanned are more supple and so more prone to melanoma, i.e. leathery tanned or just old dry wrinkled skin does not get melanoma. Smoking also kills skin elasticity but that has a whole set of other problems.
The rate of melanoma in Australia has doubled since 1970. There is a direct correlation between sunscreen strength improvements and increased melanoma.
Does sunscreen itself cause melanoma? No! Even though it is full of serious chemicals that if taken orally would be illegal. The problem is most Australians who are outside during the day are avoiding the midday summer sun and firstly not getting the protection of a normal tan and then double hit they are now over staying (compared to years gone by ) in the other times when their sunscreen offers no protection but they think that their sunscreen is working because they didn’t burn.
Finally an interesting article specifically on the links between sun and melanoma: http://www.youtube.com/watch?v=eeXtGHSt-5o&feature=related
Then using Vitamin D to cure the flu http://www.youtube.com/watch?v=bnnIfqn2c6M&feature=related
Both Youtube presentations are by US doctors