
Originally Posted by
ChloeTheRed
Regarding Retin-A:
Your skin, like virtually every other tissue in your body, has specialized stem cells. For example, your liver has liver-specific stem cells. Every time they divide in order to replace a dead cell, it gives one liver cell and one liver-specific stem cell. This can happen many times (70 or more), but after a stem cell has divided many many times, the division results in two liver cells and no stem cell. If the liver is abused, the pool of stem cells will eventually start to get smaller, which will contribute to disease. We replace liver cells naturally throughout our life, as well; some will die for any number of reasons that have nothing to do with something we did wrong. No matter how terrifically you take care of yourself, your pool of stem cells may start to shrink well before you die of old age (in many organs/organ systems, this contributes to the various diseases of aging).
We slough off dead skin all the time, and skin stem cells divide to produce new skin and replace it. When people get very old, their skin gets thin and fragile, and wounds take longer to heal. This is partially due to the fact that their pool of skin stem cells has shrunk substantially.
Retin-A artificially stimulates the skin cells to divide, producing more younger skin cells (hence that lovely glowing look you get when you've been using it). Unfortunately, there's nothing to indicate that long-term use of Retin-A doesn't result in what is basically a speeding up the aging process. To my knowledge, there have been no studies on what Retin-A use does to skin condition ten and twenty years down the road. There's no evidence that it will make you look 20 when you're 30 but then 60 when you're 50. Still, there's no evidence that it won't; personally, I'm not willing to take that risk.
I guess what it comes down to is that there is a limit to what you can do to your skin before the damage starts to show. That's why I don't like tanning and I'm very wary of Retin-A.
EDIT: I bet this is probably clear as mud to anybody who isn't a Biology Major. Sorry, that's why I've got a long way to go before I can be a professor. Just ask questions if you have any and I'll do my best to explain better.
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