With Vitamin C products – which are most effective?
Glad you asked this! This is a little hard to explain so hang in there with me. Stability is important but better quality Vitamin C products sold now are stable. Stability is not actually a measure of how well Vitamin C versions act in the skin as an antioxidant.
What is more important is how well the product protects your skin which depends on it being absorbed well into the skin and cells (bioavailability). As far as I know, no company has refuted the studies that showed that Vitamin C has the greatest antioxidant potential in skin when it is pHed to 3.5 and the concentration is about 15-20%.
Most Vitamin C esters in creams/lotions don’t meet those requirements. Also, L-ascorbic acid is harder to stabilize and that’s why it’s more expensive but it’s also easier to get a pH of 3.5 and the correct concentration. You’ll notice many companies market 10% or 15% but not 20%. At 20%, the preparations tend to be too irritating. Many with sensitive skin can’t use Vitamin C preparations at all.
In my opinion, companies try to confuse consumers with substandard products by marketing the product on stability when it’s not really the issue. Notice how they don’t talk about the pH or the concentration. Hope this makes sense. Dr. I
Read Dr. Irwin’s article on Skincare Terms & Ingredients.
Learn about Dr. Irwin’s Skin Care Regimen.