Dr. Courtney Rubin, our Chief Medical Officer, weighs in on your most pressing skincare questions.
The answer depends on the vitamin in question and what the desired outcome is. For example, retinoids (vitamin A derivatives) have a multitude of beneficial effects when applied to the skin topically, including boosting collagen production, evening skin tone, preventing clogged pores and others. Taking an oral vitamin A supplement does not have these effects on the skin.
Another example: vitamin C has a multitude of beneficial effects when applied topically to the skin, including increasing collagen production, evening skin tone and protecting the skin from photodamage. Taking vitamin C supplementation orally does not have the same effects on the skin because oral supplementation does not increase the concentration of vitamin C in the skin as much as topical application does.
On the other hand, if you want to prevent a severe form of nutritional deficiency called pellagra, which comes from a deficiency of vitamin B3 (niacinamide aka nicotinamide) and can lead to death, you have to get vitamin B3 in your diet. Topical application of vitamin B3 would not have the same effect.