We believe that the most important topical vitamins in skincare are vitamin C and A.
Vitamin C (L-ascorbic acid) is multifunctional and essential for maintaining healthy, beautiful skin. It can neutralize reactive oxygen species, regenerate vitamin E, stimulate collagen production, reduce collagen degrading enzymes, and help protect our skin against sun and pollution damage.
Many skincare formulations claim to use vitamin C in their products. However the ingredient is notoriously unstable and difficult to formulate in meaningful concentrations (sometimes formulators have a vitamin C ‘dusting’ with too low concentrations, just so that they can mention the ingredient). Looking at studies, the optimal concentration of vitamin C in skincare seems to be 10-20% (above 20%, the benefits seem to actually go down).
Often you will find less effective derivatives such as ascorbyl palmitate are used instead of pure vitamin C, so make sure to ask your cosmetic dermatologist for an evidence-based product recommendation.
With regards to vitamin A, there are different derivatives (also known as retinoids) available over-the-counter. However, only tretinoin itself (i.e. vitamin A acid, or retinoic acid, a prescription strength vitamin A derivative) fits the cell receptors, so all derivatives need to be converted into tretinoin before they can exhibit any effects. Three of the most well known non-prescription retinoids (vitamin A derivatives) are retinol (vitamin A), retinaldehyde (retinal) and retinyl palmitate (an ester of vitamin A). Conversion takes place from retinyl palmitate via retinol and retinaldehyde to retinoic acid (tretinoin).
Retinyl palmitate is the most commonly used vitamin A derivative, as easiest to formulate, but also my least favourite one. Both retinol and retinaldehyde are highly effective over-the-counter alternatives to prescription tretinoin and I often recommend them to my patients. They support collagen production, reduce sun damage, lighten pigmentation and soften lines and wrinkles.
Vitamin A derivatives are one of the best-investigated anti-ageing ingredients on the market and ideally everybody over the age of 30 years should be using one of these to support collagen production. However, vitamin A derivatives can be irritating, so should be introduced gradually and used as tolerated. Everybody is different and some people might just tolerate them once or twice per week (best to be used in the evening), which is fine.
So there you go – my top two topical vitamins are vitamin C and vitamin A!