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Ascorbic acid in the daytime
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farawayspices



Joined: 26 Jun 2009
Posts: 14

PostPosted: Tue Jun 30, 2009 5:06 pm    Post subject: Ascorbic acid in the daytime Reply with quote

Since ascorbic acid can oxidize when exposed to sun, it is safe to use if used with a sunscreen? I'm confused because I want to use it as an antioxidant during the day, but I don't want to harm my skin because it oxidizes when exposed to light (or water). thanks!
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drtodorov
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Joined: 10 Dec 2004
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PostPosted: Tue Jun 30, 2009 11:13 pm    Post subject: Reply with quote

The net effect of ascorbic acid and sun has not been studied much but might be positive even if some oxidizes. But due to insufficient data, it may be more prudent to apply it in the evening.
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farawayspices



Joined: 26 Jun 2009
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PostPosted: Wed Jul 01, 2009 12:06 am    Post subject: Reply with quote

Thanks for your reply Dr. Todorov. What confuses me is that I've been using a topical ascorbic acid product in the daytime under my sunscreen in order to prevent free radical damage. If I switch to nighttime use wouldn't it no longer provide this benefit? What should I be using in the daytime instead? I currently use a retinol product in the evening on alternate nights with an alpha hydroxy product on the other nights. Thanks again.
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drtodorov
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PostPosted: Wed Jul 01, 2009 12:23 am    Post subject: Reply with quote

If you use a really good sunscreen, it should block out most UVA+UVB anyway. Also, once absorbed, ascorbic acid stays in the skin a relatively long time, so even a nighttime application will provide above baselines skin levels of ascorbate during the day
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farawayspices



Joined: 26 Jun 2009
Posts: 14

PostPosted: Wed Jul 01, 2009 12:41 am    Post subject: Reply with quote

Can I use vitamin c at night along with the alpha hydroxy acid or retinol product?
I read somewhere (forgive me, I forget where) that sunscreen can actually be harmful to your skin if not used with an antioxidant. I figured I would be ok since I was using an ascorbic acid powder product (Philosophy's Turbo Booster) in my sunscreen. Since this might not be a good idea, what might be good to use in the am instead?
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drtodorov
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PostPosted: Wed Jul 01, 2009 9:17 am    Post subject: Reply with quote

The potential problem with C is that it becomes pro-oxidant when oxidized and some other antioxidants, like E, do not have this problem. That said, yes, it is not a bad idea to combine sun-blocking ingredients and antioxidants (as long as they do not interact negatively with each other). Some commercial sunscreens already combine sunblocks and antioxidants.
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farawayspices



Joined: 26 Jun 2009
Posts: 14

PostPosted: Wed Jul 01, 2009 10:32 am    Post subject: Reply with quote

Would a few drops of green tea tincture in my zinc/titanium dioxide sunblock be a good idea?

How about if I do ascorbic acid and water as a wash and then rinse it off in the morning - would that give some benefit without leaving behind too much to oxidize

thank you so much Dr Todorov, I love learning about these things...thanks for sharing your knowledge :D
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drtodorov
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PostPosted: Wed Jul 01, 2009 11:08 am    Post subject: Reply with quote

It may be better to apply something like green tea or pomegranate before applying sunscreen, not to mix and store them together.

A bit of ascobic acid may be ok but since it is acidic it may affect the stability of sunscreens more than other antioxidants, so it may vary depending on a sunscreen.
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farawayspices



Joined: 26 Jun 2009
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PostPosted: Wed Jul 01, 2009 4:04 pm    Post subject: Reply with quote

Or, would it be a good idea to do the l ascorbic acid wash and leave it on, then to use the retinol? So confusing, thanks for your help Dr. Todorov!
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drtodorov
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PostPosted: Wed Jul 01, 2009 5:09 pm    Post subject: Reply with quote

Retinol may increase sun sensitivity, not as much as Retin A, but somewhat. So, if using retinol and going in the sun, make sure to use sunscreen.
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farawayspices



Joined: 26 Jun 2009
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PostPosted: Wed Jul 01, 2009 5:59 pm    Post subject: Reply with quote

I was thinking of using vitamin c in water then retinol at night - is it ok to use these two together? thanks again!
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drtodorov
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PostPosted: Wed Jul 01, 2009 6:12 pm    Post subject: Reply with quote

Yes, that's ok.
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Barefootgirl



Joined: 05 Feb 2006
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PostPosted: Sun Jul 05, 2009 10:48 pm    Post subject: Reply with quote

This is the first time I've read that Vitamin C serums can become pro-oxidative on/in the skin...so I tried to look into this a little further and found this from the Linus Pauling Institute:

"Does vitamin C promote oxidative damage under physiological conditions?"

Vitamin C is known to function as a highly effective antioxidant in living organisms. However, in test tube experiments, vitamin C can interact with some free metal ions to produce potentially damaging free radicals. Although free metal ions are not generally found under physiological conditions, the idea that high doses of vitamin C might be able to promote oxidative damage in vivo has received a great deal of attention. Widespread publicity has been given to a few studies suggesting a pro-oxidant effect of vitamin C (46, 47), but these studies turned out to be either flawed or of no physiological relevance. A recent comprehensive review of the literature found no credible scientific evidence that supplemental vitamin C promotes oxidative damage under physiological conditions or in humans (48). Studies that report a pro-oxidant effect for vitamin C should be evaluated carefully to determine whether the study system was physiologically relevant, and to rule out the possibility of methodological and design flaws."

Can you please point me to further studies which show that Vitami C can oxidize in the skin when exposed to sun or light?

Thank you! BF

I have been using it under my sunscreen for years and now I am concerned!
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drtodorov
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PostPosted: Sun Jul 05, 2009 11:10 pm    Post subject: Reply with quote

Physiological conditions mean, for example, typical blood levels of vitamin C after ingesting physiological doses. Whether topically applied serum qualifies is unclear. I am not sure pro-oxidative potential of topical vitamin C under certain conditions has been sufficiently studied. At this point the concern is largely theoretical and on-balance prudently used topical vitamin C is a lot more likely to be beneficial, especially considering its good track record in skin care. Still, it may be wise to avoid situations that might precipitate potential pro-oxidative effect, such as co-applying with copper-containing creams, or intense exposure to direct sunlight (the latter is harmful in itself anyway).
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farawayspices



Joined: 26 Jun 2009
Posts: 14

PostPosted: Sun Jul 05, 2009 11:31 pm    Post subject: Reply with quote

I sometimes use this product, just realized that it has ascorbic acid and a copper ingredient:

turbo booster c powder: ascorbic acid, panthenol, zinc pca, copper pca, camellia oleifera leaf juice, dipotassium glycyrrhizate, arginine, cysteine, aloe barbadensis leaf juice.

should I be concerned??
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