Vitamin C for skin: why it matters, and serum or capsules?

Vitamin C has long been a favourite for skin, whether in the bathroom cabinet or in the kitchen. It does matter, though, whether you put it on your skin or take it in through food and supplements. If you’ve ever wondered whether a serum or a supplement makes more sense, this article explains what’s behind each route and how to find the one that suits you.

Why does skin need vitamin C?

Vitamin C is essential: your body can’t make it, so it has to come from food¹. For skin there is an authorised health claim, which reads: ‘Vitamin C contributes to normal collagen formation for the normal function of skin’².

Healthy skin contains a lot of vitamin C, considerably more than blood plasma³. Good food sources are fruit and vegetables such as peppers, citrus fruit, kiwi fruit and broccoli.

How does vitamin C get into the skin?

Skin is made up of two layers: the outer epidermis and, beneath it, the dermis. Only the dermis has blood vessels, so the epidermis gets its nutrients from below, from the dermis³.

From the outside, the route is harder. The outermost layer of the skin (the stratum corneum) keeps out water and many other substances. The authors of a review consider it unlikely that nutrients applied to the skin readily reach the deeper layers of the dermis. Their conclusion: the dermis is better supplied through the blood³.

Vitamin C serum: what’s in it?

Serums contain vitamin C either as pure ascorbic acid or in a modified form known as a derivative. Derivatives were developed with the aim of making vitamin C more stable in cosmetics and helping it get into the skin more easily⁴.

In an experiment on pig skin, ascorbic acid only penetrated when the preparation was very acidic, with a pH below 3.5. In this experiment, the three derivatives tested did not raise the ascorbic acid content of the skin. The authors conclude that with vitamin C applied to the skin, the formulation is what matters most⁵.

According to the review mentioned above, it’s still largely unclear whether vitamin C applied to the skin offers more benefit than a good intake from your diet³. Keep a vitamin C serum cool, dark and tightly closed, because ascorbic acid is sensitive to oxygen³.

Vitamin C from food and supplements: what matters?

Vitamin C from food and from supplements passes from the gut into the blood. Skin cells actively take it up from there and concentrate it³.

Supplements come as ascorbic acid, in a buffered form or in a liposomal form. Our article on liposomal, buffered and standard vitamin C explains the differences.

A review looked at ten human studies comparing liposomal with conventional vitamin C. In nine of them, vitamin C levels in the blood were higher with the liposomal form, although the formulations and doses varied widely¹. What was measured was bioavailability in the blood, not the vitamin C content of the skin. You can read more in our article on what the research on liposomal vitamin C shows.

Serum or capsules: how to decide

The two routes work in different places. The points below can help you choose.

• Route: a capsule supplies your body through the blood, while a serum works from the outside, on the surface of the skin.
• Skin feel: for pure ascorbic acid to get into the skin, the preparation has to be very acidic⁵. If your skin is sensitive, patch-test a new serum on a small area first.
• Effort involved: you take a capsule with the same meal every time, while a serum becomes part of your morning or evening skincare routine.
• Storage: keep capsules cool and dry; a serum needs a dark place and a cap that closes tightly.
• Combining both: you don’t have to choose one or the other.

Don’t take more than the recommended daily amount. If you take any medicines, check with your doctor first.

Frequently asked questions about vitamin C for skin