Vitamin C in skincare is a big trend right now in the beauty world. And rightly so! This simple vitamin has been found to scavenge free-radical damage, helps to firm skin and even-out skin tone. But despite the promise that vitamin C brings, some vitamin C products could actually be damaging your skin.
See, the most effective form of Vitamin C is ascorbic acid. (In particular l-ascorbic acid.) This is the form of C that has been studied and found to be so beneficial. But ascorbic acid is a tricky thing. Once it's dispersed in water (or aloe, etc) it starts to degrade fairly quickly, and these products of degradation can end up damaging your skin with free radicals. To remain stable, ascorbic acid in solution needs to remain in a highly acidic state (Source) and also not exposed to air. So, while it is possible to have a stable vitamin C formula, it is difficult. (The formula will turn brown once this happens, so it's fairly apparent.)
So, formulators instead turned to ascorbyl palmitate--a form of vitamin C that's much more stable. Doesn't break down and it's oil-soluble so it's great to put in a serum. Or so we thought. Turns out, once asorbyl palmitate was actually studied, researchers found out that it didn't have the same benefits that ascorbic acid has. Ascorbyl palmitate has to be activated by enzymes in order to do its job as a vitamin, and they found that the enzymes in the skin just didn't do an efficient job of utilizing the ascorbyl palmitate. They also found that when exposed to sunlight, the ascorbyl broke down and created free radicals on the skin. So, the compound that you've been using to try to reverse damage could actually be damaging your skin! (Source)
