I’m a little bit angry today, in fact, I’ve been a little bit angry for a while now as there seems to be a thing going on that is not entirely helpful. That thing is this idea that for a vitamin C serum to be good it has to be colourless. I want to talk to you all about that.

The scientific hook.

Vitamin C is a powerful antioxidant but it is also pretty unstable, especially in its cheapest, water-soluble form – Ascorbic Acid. This just happens to be the biologically active form too so it is quite attractive to brand owners wanting to make a high Vitamin C content claim.

When vitamin C oxidises (goes off) it changes colour from clear to yellowy then orange finally turning to dark brown when it is all gone to hell. So yes, there is some logic to this idea of wanting your vitamin C serums and creams to be crystal clear – makes it easier for you to know if it is active or not.

Now I know that I’m mad today but turns out some of you are too, some people are angry because they think their vitamin C serums are not doing anything, that they are shonky- possibly because of ‘bad’ formulating and possibly because of something else but the net result is that people aren’t entirely happy. I think that’s fair enough.

So can crystal clear formulations solve this problem?

Maybe but maybe not.

See as a formulator I deal with lots of materials every day and many of them are colourful – browns, greens, oranges, yellow, red even. I don’t want some half-baked idea whizzing around the internet and putting a stop to both mine and my customers creativity. More than that, some of these colourful ingredients might just have a positive role to play in making these vitamin C products work well.

Here are some examples of coloured ingredients that might make it into a vitamin C product:

Rosehip Oil (natural source of carotinoids which are natures vitamin A)

Vitamin A (retinol, Retinyl palmitate – useful in an A, C and E product)

Coenzyme Q10 (very, very yellow)

Vitamin E (can be quite browny orange and may affect the colour of a formula when used at 0.5-2%)

Honey (honey coloured – can be anything from light yellow through to brown)

Seaweed (Different chlorophyls make this anything from greeny blue through to brown)

Folic Acid (very, very yellow)

Green Tea (brownish)

Calendula Oil (very yellow through to orange)

Turmeric Infused Oil (bright yellow)

Spirulina (very bluish-green)

Hemp Seed Oil (very green)

Some grape extracts (brown to purple)

Activated Charcoal (black/ grey)

Alpha Lipoic Acid (yellow)

Dragons Blood (from orange through to brown)

Sodium Phytate (A useful chelating agent to help stabilise the vitamin C – brown)

Various fruit and veg extracts including Melon, Olive Leaf, Quinoa- usually from pink to yellow to brown.

Many blended actives from manufacturers

Many essential oils

Vanilla Oleoresin.

Benzoin Tincture.

So what’s going on here.

What I think is happening here is that a couple of brands who make pretty bland (and there’s nothing wrong with bland BTW) Vitamin C serums that focus on just being vitamin C serums – nothing else- are trying to set themselves up as being somehow better (or best). I think that’s disingenuous really given that these guys give no evidence that their products are indeed better than anything else and worthy of this elevated status. As a formulator I am well aware of how hard it is to make a stable vitamin C serum or cream but I’m also aware of how some of the above ingredients and many more besides can potentially add to the efficacy of a formula and can bring other, supportive benefits to the product, thus turning a single-purpose product into something that can do so much more. That said, I am also aware that some of these other ingredients can also add to the chaos of the formula and make it even harder to stabilise. In short, it is all too complex to just brush off with a ‘if it has a colour it’s crap’ one-liner. I hate that kind of marketing, it always makes me wonder what the writer is trying to hide…..

Is colour and colour change a guarantee the product is a) crap to start with and b) oxidising out of vitamin C?

So hopefully we can see that a coloured vitamin C product does not have to mean that the formulator is trying to pull the wool over your eyes and ‘hide’ oxidation because they can’t figure out how to stop it so that leaves us with a colour change. Sure a change in colour from crystal clear to dark brown is a worry but what about a change from a light yellow to an orange or an orange to a brown? What about a product that starts off a colour because of the above? What do we do then?

While all colour changes mean that something is going on, that is not the same as saying that it’s a guarantee that the vitamin C has all gone. Colour changes can be a fairly standard part of ageing of a natural and especially an organic formula and while that does mean some chemical changes have happened it only matters if those changes mean the product will no longer work, will be irritating or will no longer meet its label promise. Let’s have a closer look at that.

A common non-critical colour changes typical in organic and natural products.

Plant extracts including many vegetable oils contain chlorophyl pigments that can break down over a product’s life span. Being chlorophyl it is a no-brainer that these pigments will be light reactive and so UV radiation will change their colour – but UV also breaks down vitamin C so most vitamin C products are protected from UV by their packaging. The most common way chlorophyl pigments break down in vitamin C formulations is by interaction with the acidity in the formula. There is more than one type of chlorophyl and some break down to become colourless and others become brown. So your vitamin C serum browning marker may potentially be skewed by little old chlorophyl. Now if chlorophyl breaks down it may increase the likelihood of the whole formula going to crap but it also may not, it depends on how much is in there and how quickly it breaks down but suffice to say the visual effect may give rise to false alarm! From a formulators perspective it may well be a good idea to avoid chlorophyl containing actives in a vitamin C serum or cream but as chlorophyll is usually present as part and parcel of a natural plant extract or active virgin quality oil that can be easier said than done. Being non-biologically active whether a cosmetic product contains chlorophyll or not is not important and will not usually affect the performance of a product. So it is possible that a product be quite brown but still contain the specified amount of vitamin C. This discussion here is quite useful.

So what can we do?

The main thing we can do is test. Sure, very few people are going to go out and buy heaps of different serums and get them assayed to see how much vitamin C is left vs what the formula says but if you REALLY REALLY want to know (i.e: you are a brand who wants to know what’s real rather than what’s just in your imagination so you can run a factually correct marketing campaign/ educational blog) then it might be worth doing.

A Vitamin C assay costs between $200-$300 each (plus GST – prices are a guide only and are dependent on provider and method used and are in AUD). The testing takes a day or so and only a few grams of product are needed. This is the sort of testing I recommend and do on my formulations and for my brands that want to make a specific claim based on a specific active being present. Not all vitamin C serum / creams are sold on a percentage of C basis, some just claim to contain Vitamin C and don’t specify the amount.

OK so we test a few products, find they fall short of their Vitamin C concentrations and get mad, but is there anything more than that to worry about?

Vitamin C WILL break down over time no matter how good the formulator is so there will be some oxidation happening eventually. In a decent formulation this breakdown of Vitamin C will be annoying but will not be much more than that. It is also worth remembering that oxidation happens over time and bit by bit, it isn’t like the vitamin C is all there one minute and not there the next. To work out whether a bit of vitamin C oxidation is going to make the product more irritating or not we have to have a look at what the vitamin C turns into.

Vitamin C degradation.

Ascorbic Acid can react with various different things to give different results. One of the most dramatic reaction pathways in terms of fast colour change is the Maillard pathway of degradation – this is the reaction that happens on an apple when you cut it then leave it – it goes brown quite fast. Ascorbic Acid is a reducing carbohydrate that reacts with amino acids, peptides and proteins in a reaction that turns brown. This means that it is a good idea to not have peptides, amino acids or proteins in your vitamin C serum – and most vitamin C serums don’t have these so this most dramatic of pathways is rarely enacted to be honest. That’s not to say that a vitamin C serum can’t go brown – I’ve had products of my own go brown before their first birthday is up – but that the pictures you often see of vitamin C turning dark brown very quickly indeed will most likely be using this Maillard pathway reaction as it looks the most dramatic.

But that isn’t the only pathway.

Oxygen can also cause a breakdown of the vitamin C but in low pH environments (typical for vitamin C products) this can be relatively slow unless there is a catalyst – some metal ions are catalysts and these may be present as contaminants in the formula (Lead>Zinc>Cobalt>Iron> Manganese>Nickel> Calcium> Magnesium). It is important to note that these contaminants may even be present in the Ascorbic Acid – it’s hard to get 100% pure anything.

Oxygen catalysed breakdown of vitamin C proceeds somewhat like this: Ascorbic Acid > Dehydroascorbic Acid (still biologically active) > Diketogulonic Acid (BROWN and not an active form of Vitamin C > HydroxyFural (BROWN and not an active form of vitamin C). So from that you can see that there can be a chemical change in the vitamin C without it changing the colour of the product immediately – Dehydroascorbic Acid is less likely to brown than Ascorbic Acid according to a 1996 study into this.

But eliminating oxygen doesn’t eliminate all of your problems as vitamin C can also break down anerobically (without oxygen). In an oxygen free environment Vitamin C can break down to form Furfural, 2-Furoic Acid and 3 hydroxy-2Pyrone. Furfural is a colourless oily liquid but it does darken very quickly when exposed to air but as we are talking about anaerobic breakdown here it may well be possible to have a critical breakdown in active vitamin C to Furfural in an airless product without seeing that reflected as a colour change. I say might because I am not sure of all the other reactions and changes that go on around this reaction – it is also possible that this reaction critically destabilises the formula. I don’t know.

On top of that UV can also break down vitamin C but again most vitamin C serums know this and are protected by their packaging and in any case, in the grand scheme of things UV is the least of our worries (according to Vitamin manufacturers DSM who rank light way below Alkalinity and oxidising agents as a potential source of degradation and put heat and humidity somewhere in the middle.

The bottom line is that colour change is just one thing that can indicate a chemical reaction in your vitamin C product. Sure it is quite dramatic and yep it might well happen but it is not really fair to say that it is the only or even main way to always tell if your product has shat its self.

As an aside you may be interested to know that your vitamin C product might release a bit of gas, change pH or start to smell different as other signs that something chemical is going on.

So what should we all do then?

What I’d like people to understand is that stabilising vitamin C into a usable and cosmetically acceptable formula is not easy and you really are trying to hold back the tide, especially if you are trying to achieve a natural or organically certified product. I’d like people to remember that colour change is not always a cause for major alarm, that a coloured product is not a sign that you are being duped and that a reduction in vitamin C potency over a products shelf life is not necessarily a show stopper. In the food world it is widely accepted that vitamin C levels will drop over time and often the stated value on the pack is the end point value (at the end of the shelf life) rather than the starting point. I found data showing ranges of between 75-97% retention after 12 months room temperature to be acceptable – it might be that this is also acceptable in a cosmetic product. The problem with cosmetics is that we have tended towards marketing what we put in (20% Vitamin C, 10% or 5% for example) rather than what we are left with. Alternatively we have brands who have chosen to limit their formulation complexity as a way of (hopefully) increasing stability. While this is totally rational and even sensible, I can’t stand by and let that hamper creativity and experimentation – we don’t know everything about vitamin C yet and it would be a shame for brands to give up just because the market has only been groomed for simplicity.

I believe it is best to market our products based on evidence gained on what the product actually does and how it actually performs rather than just opt for a simple numbers game or ‘talk down the opposition’ positioning. A simple assay or two can validate the Vitamin C content, a stability test can check for pH stability, pack compatibility and general form and function and then a patch test can do the final check to make sure any oxidation hasn’t made the formula more irritating. These simple steps will ensure that we can keep pushing the envelope with regards to vitamin C formulations while meeting consumers expectations of a good and safe product. So let’s get on with it shall we and if you want to make and/or sell an orange, pink, green or brown vitamin C product please feel free to do it!