wcelliott
1st September 2008 - 05:51 PM
The problem is that there are several mechanisms at-work, so your question doesn't have just one answer, but several.
The simplest answer involves growth hormones. When there's a problem with the pituitary gland, sometimes it generates too much growth hormone, and the condition "acromegaly" occurs, resulting in "gigantism". There's a Chinese NBA player with it, and those who've seen "The Addams Family", the old TV series, might remember "Lurch", he had it, too.
An interesting side-note is that there's a theory that says there's a hereditary "set-point" which triggers the reduction of the level of growth hormone released, and when the set-point is reached early, people as adults look "cuter" (more juvenile) than others who get bigger and closer to "acromegaly-ish". Note how many really handsome/beautiful actors are also much shorter than average.
Anyway, one of the other pieces of the puzzle involves Vitamin D, which is a precursor to a "quasi-hormone" that cells release when they get crowded by neighboring cells. (This has nothing to do with acromegaly, but everything to do with tumor growth.) There's a normal response that happens when we're injured or wounded, where cells *must* multiply faster to repair the damaged tissue or close the wound, but the signal "Enough already!" is derived from Vitamin D. When the "Enough already!" hormone is released, it tells the nearby cells to stop reproducing.
It's been recently realized that people living in colder climates have a higher rate of cancers, and it's been postulated (and demonstrated) that Vitamin D deficiencies are at least partially to blame for the higher cancer rates. (One of the sources of Vitamin D is sunlight on bare skin, the body makes massive quantities with relatively small exposures to sunlight.)
It makes sense that if someone is deficient in Vitamin D, that they can't generate enough of the "Enough already!" hormone, and cells keep multiplying, and with every replication, the chances of a cell mutation leading to cancer increases, and the rest is obvious.
The bottom line is that the Recommended Daily Allowance for Vitamin D should really be increased to about 2000IU/day. The current RDA is about 1/5th what it should be to prevent cancer. It's the cheapest and most effective way to prevent cancer, and yet the hippies that work at the vitamin/health food stores never heard of the Vitamin D deficiency-cancer link, and they usually one sell one brand, if they sell any. They can extol the virtues of dung-beetle saliva all day, but the one thing they never heard of is how Vitamin D helps prevent cancer.
Yeesh!
(Sorry, pet peeve of mine.)
http://www.msnbc.msn.com/id/19098606/"Building hope for one pill to prevent many cancers,
vitamin D cut the risk of several types of cancer by 60 percent overall for older women in the most rigorous study yet.
The new research strengthens the case made by some specialists that vitamin D may be a powerful cancer preventive and most people should get more of it. Experts remain split, though, on how much to take.
“The findings ... are a breakthrough of great medical and public health importance,” declared Cedric Garland, a prominent vitamin D researcher at the University of California-San Diego.
“No other method to prevent cancer has been identified that has such a powerful impact.”Not the link I was looking for, but this one comes close:
http://mcb.asm.org/cgi/content/abstract/16/1/318