In recent years there has been a movement in the online skincare and general beauty community away from buzzword-based DIY/natural/organic ingredients and products, to a more science-based approach to looking after your skin. The popularity of skin care brands such as The Ordinary have a huge role to play in this movement – naming your products by the main ingredients (“niacinamide 10% + Zinc 1%”, “mandelic acid 10% + HA”) while being at a relatively affordable price, forces consumers to read into the ingredients they use on their skin. Which is of course a positive development, you would think. Even opening the skincare page on Boots leads you to different Vitamin C products, retinols, “anti-pollution” products and micellar waters. It seems beauty companies are responding to the demand in products targeting specific issues for specific skin types, but there comes a point where we as consumers need to stop and take a step back; what started as a self-education and interest has led to the same marketing ploys and a new set of buzzwords.
Topical use of vitamins (retinol (A), niacin (B3), ascorbic acid (C), B12) have been incredibly popular, despite it being well established that they are important for healthy skin when ingested. What a lot of marketing fails to mention is how successful these actually are on your skin, or get away with vague language that easily wash over us. Vitamin C and its derivatives are a great example of this. The rationale behind using vitamin C topically is that it is important for many cellular functions, stimulates collagen synthesis and is a great antioxidant protecting against UV-induced damage (different from sunscreen which absorbs UVA and UVB rays!). However, the use of vitamin C as a topical treatment in skincare is actually poorly understood.
Unlike Vitamin A (retinol, retinaldehydes, tretinoins), there isn’t a huge body of work that would support the claims about vitamin C made by [insert major cosmetic brand], more specifically randomised human clinical trials. Our skin seems to contain a lot of vitamin C compared to other tissues, despite studies showing high variability, probably due to handling the tissues and very little control across studies over the skin location and age of the donor. Most of the vitamin C in your skin is transported there from the blood into the cells in all layers of the skin, where specific transporters for ascorbic acid are found. When there is enough vitamin C in your diet, you won’t find increasing levels in the skin, as with most vitamins there is an optimum concentration. Lower vitamin C content has been correlated with photo-aging, caused by radiation, pollution and other environmental factors. Topical applications of the antioxidant may have potential, in that case, to restore levels particularly in the stratum corneum (the outermost layer).
Vitamin C, at neutral pH can’t actually penetrate through the skin to target deeper layers, suggested by in vitro studies showing removal of the stratum corneum increasing delivery. Despite having a small molecular weight, chemically it still has difficulty. At a low pH, the uncharged version of vitamin C, ascorbic acid, is formed and penetration into the skin can occur according to studies based on laboratory animals. Whether or not it can penetrate through the stratum corneum in humans is yet to be known, and these pH levels are too acidic for consumer usage. Another issue with ascorbic acid now, is its instability. In terms of day-to-day application, you wouldn’t want an ingredient that degrades on exposure to oxygen (or heat and light) and renders itself useless before it even has the chance to penetrate your skin.
The challenge has been producing a derivative that is stable and stores well, while being able to penetrate the skin into the relevent layers, AND THEN being able to convert into its most biologically active form. Ascorbate phosphate, for example, is a synthetic derivative that is more stable than ascorbic acid, but doesn’t penetrate or function as well. The issue with these derivatives also, is that there is not enough evidence to confirm their bioactivity.
The functions of vitamin C in the skin are widely studied for health reasons, since its deficiency comes in the form of scurvy. Besides being a very effective antioxidant, it also regulates collagen biosynthesis which can affect wrinkles and elasticity, as well as having a role (yet to be fully established) in wound healing and hyperpigmentation. The best way to get vitamin C for these functions, is your diet – bell peppers and citrus fruits as the obvious culprits. Interestingly, because of its antioxidant nature the vitamin can however be used to help the formulation of a skincare product, preventing oxidation of oils in the formula and supporting other antioxidants; vitamin E is often used for formulation enhancement too.
There are other products and ingredients in the market that work better and have more evidence (through human clinical trials) supporting them. For antioxidant effects, retinols as well as reservatrols are good contenders. Retinol is also widely used with success for anti-aging purposes.
Vitamin C does have a place in skincare and with most skincare trends can be fun to try out, but is it worth investing in it for its supposed properties? Probably not until there is more time, energy and money put into its research and product formulation.
Extras
“The Roles of Vitamin C in Skin Health” – open access extensive review article for interest
Vlogger called Kenna who does great videos on biochemistry and skincare, here’s a link to their video on vitamin C
pasteursflask 