You got it.You hit the nail on the head.You enjoy being cancer free,so do I.And if you actually were to look at the real data you would see that the canadian cancer society recently upped it's recomended daily value of vit d requirement to 1,000 iu's...not the glass of milk you reffer to.
The reason for this is that numerous ,numerous studies are showing that those who have the highest levels of vit d in the bloodstream have the lowest levels of deadly cancers and many other dieases.It is estimated that 200-500 people die from too little sun in comparision to too much sun.
The cdn gov't is the only country in the world currently looking at swine flu insulation thru increased vit d in the bloodstream.Viroligist for a long time have been pointing out a link.Ever notice when flu season occurs? All over the world...in wintertime,when vit d levels fall.
5-30 minutes once or twice a week is woefully inadequate.Our ancestors spent almost all of their time outdoors and would have been producing up to 10,000 iu's a day.So why do we just need.never mind 200,or even a 1,000 iu's.Rheinhart Veith,who is a major vit d researcher right here in Toronto says upwards of 4,000.
200 UI was just for adequate intake..or around the minimum
I am not really up on my Vitamin D research however there is no debate as to the benefits of vitamin D. So i did a little:
The research is clear.
One (of many) such publications:
Holick MF, Sunlight, UV-radiation, vitamin D and skin cancer: how much sunlight do we need?Adv Exp Med Biol. 2008;624:1-15
An the one that got some notoriety in the Global Mail and others:
Heaney RP et al, Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J of Clin Nut, Vol. 85, No. 6, 1586-1591, June 2007
http://www.ajcn.org/cgi/content/abstract/85/6/1586
In terms of the daily requirements required to reduce the cancer risk the research is ongoing. Realize that is is a fat soluble vitamin therefore toxicity is a problem.
However,
The issue in this thread is the effects of suntanning.
Exposure to the skin does cause skin cancer. no doubt.
Now, Whether or not the vit-D generated during that sun exposure will prevent that cancer is at this point unlikely.
"Laboratory and animal evidence as well as epidemiologic data suggest that vitamin D status could affect cancer risk. Strong biological and mechanistic bases indicate that vitamin D plays a role in the prevention of colon, prostate, and breast cancers. Emerging epidemiologic data suggest that vitamin D has a protective effect against colon cancer, but the data are not as strong for a protective effect against prostate and breast cancer, and are variable for cancers at other sites. Studies do not consistently show a protective effect or no effect, however. One study of Finnish smokers, for example, found that subjects in the highest quintile of baseline vitamin D status have a three-fold higher risk of developing pancreatic cancer."
Davis CD. Vitamin D and cancer: current dilemmas and future research needs. Am J Clin Nutr 2008;88:565S-9S.
Davis CD, Hartmuller V, Freedman M, Hartge P, Picciano MF, Swanson CA, Milner JA. Vitamin D and cancer: current dilemmas and future needs. Nutr Rev 2007;65:S71-S74.
That article that was posted in the globe and mail, inspired by recent research, also which includes some of the information Underdice presented:
http://www.theglobeandmail.com/life/article756975.ece
contains this paragraph:
"Only brief full-body exposures to bright summer sunshine — of 10 or 15 minutes a day — are needed to make high amounts of the vitamin. But most authorities, including Health Canada, have urged a total avoidance of strong sunlight or, alternatively, heavy use of sunscreen. Both recommendations will block almost all vitamin D synthesis."
In summary,
Vit-D good. Get some
Sun exposure (UV rays..as in suntanning beds) exposure is not you only way of getting some, and is not safe.
The risks out weigh the benefits