Is topical vitamin C truly an effective ingredient in skincare, or is it better to just eat it?
A hero ingredient touted by cosmetic companies as a skin saviour, vitamin C indeed has many super powers. It helps to protect skin from UV damage, promote collagen synthesis and the formation of stable collagen molecules in the skin, fade scarring, brighten the complexion, while also reducing hyperpigmentation, wrinkles, redness and breakouts. It improves skin hydration, protects from damaging free radicals (generated due to exposure to ultraviolet light from the sun) and increases skin elasticity. Studies have shown that topical vitamin C preparations not only improve skin appearance by reducing fine lines and wrinkles but it is also good for wound healing. Plus, it protects from or lessens the severity of sunburn.
So if a product says it contains vitamin C, that’s great right? Not necessarily. How it gets into the skin, and how it is made is quite a complex story.
Getting it into the skin
We know skin contains vitamin C in quite high levels, suggesting it is required there and that there are various functions in the skin for which it is key. There are quite a number of other biological roles we are beginning to understand as well, all together suggesting that vitamin C is really important to the skin, says Juliet Pullar, research fellow, Department of Pathology and Biomedical Science, University of Otago.
“As vitamin C researchers, we tend to think the best way to get vitamin C into skin is to eat it, and
that can be via wholefoods, drinks or tablets,” says Pullar. “The lower layer of skin has blood vessels and the nutrients we eat can make their way from the gut to the blood and then into the tissues, including skin. Because humans can’t make vitamin C, unlike most other animals, we need to eat a regular source to maintain our tissues at optimal levels. So if you eat well with lots of fruit and vegetables, your skin, at least theoretically, should have high levels.”
Because topical vitamin C can only penetrate so far, in order to get the maximum benefits of vitamin C it’s important to include dietary sources, too, agrees Sarah Quilter, founder of Tailor Skincare.
“Topical vitamin C is also important because the epidermis does not have a reliable blood supply, making it unlikely that dietary forms of vitamin C will reach the epidermis,” says Quilter. “Similarly, including foods rich in vitamin C into your diet is very important because it’s unlikely that topically applied vitamin C will make its way past the epidermal layers and into the dermis. The dermis has a reliable blood supply therefore it has access to dietary nutrients carried into the skin from the blood.”
This is one reason why the cosmetic industry is interested in modifying it – to increase its ability to penetrate the epidermal layer, explains Pullar. However, you also need to keep the part of the molecule that is involved in its biological activity working.
Fundamentally, the function of vitamin C is to donate electrons to other molecules and in the process it becomes oxidised and inactive. Vitamin C is very unstable and it can become easily oxidised in aqueous solutions or cosmetic formulations, in which case, it will no longer be active in the cosmetic formulation. For example, exposure to air or heat can cause vitamin C to become oxidised, forming dehydroascorbate, which is an inactive form of vitamin C. Therefore it is really important for the cosmetic industry to have stable formulations, which maintain its activity, for applying it to the skin.
“Vitamin C is highly water-soluble, which tends to suggest it won’t cross the top layer of skin,” says Pullar. However, vitamin C exists in different forms depending on the pH. At low pH, it is present as ascorbic acid (an uncharged form), whereas at neutral pH (7) almost all is present as the ascorbate anion, which is a charged form. The charged form, ascorbate, is very poor at crossing the top layer of skin. Whereas ascorbic acid is slightly better and you will get some vitamin C penetrating the skin in this form.
“Therefore sometimes vitamin C is formulated at low pH, for example below pH 3.5 to increase its ability to penetrate into skin. This also aids its stability,” she says.
Natural versus synthetic
While ascorbic acid (most common form of topical vitamin C) is naturally occurring, its unstable nature when exposed to oxygen means it has to be stabilised to have any of the benefits, and this is often achieved by producing a synthetic version.
“Ascorbic acid may be obtained from plant sources, or more commonly by a combination of fermentation/enzymatic processes and chemical modification,” says Dr Andrew McLeod, manager Global Derm and NZ Medical at Douglas Pharmaceuticals. “The decision on whether it is good or bad might come from the impurity profile – what else is in the material that may be a by-product from the method of manufacture. And the user’s perception – naturally sourced may be perceived as being safer.”
From a scientific point of view there is no difference between a synthesised version or a natural version of vitamin C. “They are the same chemical, and from our previous work, they are absorbed absolutely equally. The body is unable to distinguish between them,” says Pullar.
Synthetic ascorbic acid, however, such as that from petrochemical origin in nature-identical form, is not permitted by the provisions of the NATRUE standard. NATRUE* do, however, sanction ascorbic acid as an approved ingredient if it is “either natural or derived natural”. “Fermentation is quite often the means to produce ascorbic acid nowadays since the industrialised biotech approach of this substance from microorganisms is quite a common [one],” says Dr Hana Mušinović, regulatory and scientific manager of NATRUE.
Natural cosmetic brand Trilogy, which is NATRUE certified, has recently released a Vitamin C Booster Treatment, which includes a unique dispensing mechanism, which pops with freshness when vitamin C powder (ascorbic acid) is released into a hyaluronic acid concentrate. The fresh activation ensures the vitamin C potency levels are at an optimum if used daily for two consecutive weeks.
Tailor Skincare also uses naturally derived ascorbic acid in its Gold Dust product, but as Quilter explains, “it’s not as simple as rubbing vitamin C powder on your face to get the desired benefit”.
The science and formulations
According to Vanessa Ngan of DermNet NZ a correctly formulated topical vitamin C preparation is a costly process. Many companies claim skin benefits but have no rigorous scientific testing to back them. And many topical vitamin C preparations do not penetrate the skin sufficiently to make any difference.
“The truth is many of the available formulations contain very low concentrations of antioxidants that are not well absorbed by the skin. Vitamin C is an antioxidant, which when manufactured into a stable topical formulation, is proven to be effective in protecting against photoageing of the skin,” says Ngan.
A stable formulation can be achieved by converting ascorbic acid into a more stable derivative, e.g., sodium ascorbyl phosphate, ascorbyl glucoside, magnesium ascorbyl phosphate and ascorbyl palmitate; and adding antioxidants to protect the ascorbic acid from oxidation, explains McLeod. Wunderbalm Vitamin C Serum contains 10 per cent sodium ascorbyl phosphate, a naturally occurring water-soluble derivative of vitamin C. “It has a salt molecule attached to it, allowing it to easily penetrate the skin’s lipid barrier,” says Wunderbalm’s Caterina Schiffers. The penetration of ascorbyl phosphates into the skin have been demonstrated in studies**; and in promoting collagen formation demonstrated in an in-vitro study**.
And, because of its wide spectrum of action, sodium ascorbyl phosphate is suitable for a wide range of skincare products. It is also the perfect companion to vitamin E acetate, a common oil-soluble equivalent. Being coated in a lipophilic substance such as vitamin E will help with epidermal delivery. In other words, increase absorption into the skin.
Can vitamin C be naturally occurring in a product?
Yes, for example, kiwifruit and rosehip flesh are both known to contain vitamin C (ascorbic acid), so including these materials in a product would bring that into the formulation. However, due to the unstable nature of vitamin C in its natural form they are likely to have a minimal effect on the skin. “If it is a lipid soluble plant extract, it is unlikely to have any vitamin C present in the first place,” says Pullar.
However, Australian natural skincare brand Biologi has found a way to bottle 100 per cent active, pure plant extracts – Australian natives finger lime, kakadu plum, Davidson’s plum and quandong.
Biologi founder Ross Macdougald, a formulation chemist and owner of Plant Extracts (an independent manufacturer and supplier), has spent many years studying plant science and skin science, which he says led him to understand how vitamin C is produced in a plant, how it is kept stable and active within the plant and most importantly how it is delivered to plant cells. “Nature has created a way not only to keep plant nutrients stable, such as vitamin C, but to move it within itself without affecting its potency and finally delivering it to the cells that require the nutrients. Human cells act in a very similar way to plants, and also need many nutrients that plants produce, such as vitamin C,” Macdougald says.
This led him to create an extraction method that mimics the internal mechanism of a plant. This means that what is extracted is not only the nutrients but also the “liquid matrix with the plant that keeps the nutrients stable along with the activator that delivers the nutrients directly into the cell”. It’s believed to be a world-first technology that allows, for the first time, the delivery of natural vitamin C to the skin along with many other phytonutrients.
Vitamin C and the sun
The antioxidant effect of ascorbyl phosphates in protecting the skin against UV damage has also been demonstrated in a number of studies. A study done by Farris et al found a UV protective effect by vitamin C. Using an application of 10 per cent vitamin C showed a statistically significant reduction of UVB induced erythema at a rate of 52 per cent along with sunburn cell formation by 40-60 per cent. This further emphasises the benefit of post-sun topical application of vitamin C, says Quilter.