A guide to vitamin c

I know #vitaminc is a topic I talk about a lot on social media but there’s a good reason for this. It is really difficult for a consumer to choose the correct products based on what is actually in a product and find reliable evidence. Skincare marketing is clever (we’ve all seen those adverts claiming 99% of women are happy with the results - based on 4 women) and the product claims can be tricky to navigate, unless you are armed with accurate information.

There are different forms of vitamin c but generally, brands will just state the ingredient as ‘vitamin c’ because anyone with an interest in their skin will be aware of the wonders of this ingredient. The purest form of vitamin c is l-ascorbic acid (LAA) and this is the only type of vitamin c which is beneficial to skin improvement. LAA comes in various percentages but generally 10-20% is standard and quantities over 20% have not been demonstrated to provide a bigger benefit. It will only irritate the skin. LAA has clinically proven benefits in vivo (living human tissue); it promotes neocollogenasis (collagen production), photo protection (works fantastic under an SPF to reduce free radical damage to the skin DNA and UV damage) and is a mild tyrosinaise inhibitor (reduces brown pigmentation marks). Although this sounds like a wonder ingredient, there is a very good reason that a lot of brands do not use it. It is unstable. This means to use LAA in a formulation which doesn’t oxidise (essentially go off) quickly, is a suitable pH around 3-3.5 and is aesthetically pleasing to use, costs the manufacturer a fair whack which is kindly passed on to you, the consumer.

Now, there are derivatives of LAA such as 3-0- Ethyl ascorbate (EAC) and Magnesium Ascorbyl Phosphate (MAP). There is evidence that EAC is absorbed, however, this was in an animal ex vivo (outside of a living organism) study, rather than human. There are promising elements, in that it has been shown to improve pigmentation in vivo, however there is no data to demonstrate that it helps to promote collagen production to help with anti-ageing and promote photo protection. The lack of proven benefits could be due to the EAC not having the ability to convert to LAA in the skin.

Looking at MAP now, there seem to be some more benefits compared with EAC. One feature of MAP is its ability to work in the absence of an acid pH, which may be good for very reactive skin, however, 10% LAA is likely to give better results. With regards to absorption, MAP has demonstrated a limited absorption and only had animal testing ex vivo which leaves us questioning what the absorption rate would be like in humans and does not demonstrate a greater stability within a product. The benefits of MAP, however, outweigh EAC. MAP has demonstrated an ability to convert to LAA and promote collagen production but only in in vitro studies (artificial testing). Additionally, MAP has also demonstrated the ability to improve pigmentation in human in vivo tests but currently there is a lack of data with regards to photo protection.

Simple right? LAA is currently the only type of vitamin c which our skin can utilise to provide all the benefits available. I would always recommend Obagi Professional-C 10-20% LAA where possible, especially for the collagen boosting benefits, however, there may be other options depending on your budget and skin concern.

Contac Leah if you need advice on your skincare regime or skin concerns.


Pullar JM, Carr AC, Vissers MCM. The Roles of Vitamin C in Skin Health. Nutrients. 2017;9(8):866. Published 2017 Aug 12. doi:10.3390/nu9080866

Stamford, N.P.J. (2012), Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives. J Cosmet Dermatol, 11: 310-317.

8 views0 comments

Recent Posts

See All