Tuesday, June 01, 2010
Sunscreen 101: Anti-Oxidants and Photoprotection
If you read my giant post yesterday on anti-oxidants, you likely noticed that I kept bringing up photoprotection and how anti-oxidants helped repair sun damage. So, what is all that about? Can you use anti-oxidants instead of sunscreen? Are they an adjunct?
When your skin is exposed to UV radiation, free radicals are induced. They start to go around in your skin, creating their damage. Luckily for all of us, our skin has its own anti-oxidant protection system at the ready, able to absorb those free radicals and protect our skin from damage. But there are problems. First, your own existing anti-oxidants are often not enough if the sun exposure is prolonged. The free radicals overwhelm the system, so to speak. The cells in the skin respond by making more anti-oxidants, but this takes time. The lag results in time for the free radicals to create sun damage.
So, there is an anti-oxidant production lag. Could you overcome this with exogenous (aka, not made by your body) anti-oxidant? Yes, you definitely could. In fact, you probably should. You have a choice of taking something in by mouth or applying it to your skin. By mouth is recommended by many dermatologists for several reasons. First, since the anti-oxidants are circulated by your circulation, you know they will get down to all layers of your skin. Second, you don't need to worry about rubbing something off. However, topical does have the advantage of immediate gratification. No need to plan ahead and take something that your body needs to absorb and then circulate to your skin. However, note that since you are trying to negate that lag time, you need to apply before sun exposure, not after.
So, which anti-oxidant should you use? There are studies out there for pretty much every anti-oxidant possible that show protection from UV damage associated with anti-oxidant use. Vitamin A (and its retinoid derivatives), beta-carotene, green tea extract, you name it and there is a study. So, you can use your anti-oxidant of choice.
Keep in mind that with topical applications, those anti-oxidants can actually backfire on you. True story, the topically applied ones can be hit by the UV radiation and become free radicals themselves. I haven't found out yet if this is true of the ones you take by mouth, but it definitely is known to happen to topically applied ones. It isn't a universal problem, and it does depend on the anti-oxidant and the formula. (For those of you that have been reading the news over the past week or so, this is likely the cause of the retinyl palmitate issues when exposed to sun increasing tumorgenesis. It's likely not a problem always with that ingredient, but rather in certain formulations.)
Finally, what about anti-oxidants acting as sunscreens? It's true, Retinyl esters (so, compounds related to Vitamin A) have been found to actually absorb some UV radiation, with peak absorption at about 325 nm (that's short range UVA if you're wondering). However, the overall effect is not broad spectrum and is to a lesser extent than the current FDA approved sunscreen ingredients. I'd stick with sunscreens for that purpose.