Monday, February 1, 2010

Polyphenols: Coumarins

Coumarins - found as coumaric acid - are very powerful anti-oxidants that smell like either vanilla or freshly mown hay (it's what smells nice after clover is cut). Because of this lovely smell, it's often used in perfumes and fragrance oils.

Coumarins are good anti-inflammatories, and they reduce both oedema and redness on our skin. They are anti-bacterial and may offer anti-fungal activity. Some studies have shown promise using coumarins to treat Candida albicans, although "more study needs to be done" (in other words, they're not sure).

Coumarins are an interesting addition to sunscreens. They block out the short wave radiation (280 to 315 nm) but allow the longer wave radiation that allows us to get a nice tan.

But coumarin has a dark side. It is suggested we don't ingest more than 0.1 mg per kilogram of body weight due to possible liver damage. It's not known if coumarin applied to the skin can enter the blood stream, but just to be safe the EU requires labelling for any product containing more than 10 ppm (leave on) and 100 ppm (rinse off). And it has been banned as a food additive in most countries - it happened in 1978 in the US. Why? Because is is a powerful anti-coagulant - it's the drug Warfarin - and it can be used as a rodent killer by making the poor animals bleed out and fail to process Vitamin K.

This doesn't mean we should avoid coumarins in our diet or our products. Coumarins are found in coconut oil, lavender, liquorice, Tonka beans (hence the vanilla scent), apricot, cherries, strawberries, and cinnamon. They offer anti-fungal, anti-inflammatory, and anti-oxidizing properties. They can reduce water retention and reddening of the skin, and may protect from UV damage.


Anonymous said...

I love the scent of coumarin, and I've bought a dried form of it with the idea of using it in my syndet. But, comments on the Internets seem to caution against its use.

Is it safe? What are the issues?

Thanks for any sound advice...

p said...

Hi Susan, what is the link between furocoumarin and the coumarin you're discussing in this post? Is coumarin actually a class of molecules, of which furocoumarin is one type?

I know that the reason that bergamot essential oil (and lime and lemon oils) are not recommended for leave-on products is that their furocoumarin content makes them phototoxic. Which leads me to wonder, is coumarin in general phototoxic? I made a lovely lovely tonka bean tincture that makes an awesome base for perfume, but I'm concerned about the user spraying it on skin that gets exposed to the sun. Yet from what you wrote, it sounds like coumarin could actually offer some sun protection? Fascinating and confusing! Can you shed some light on furocoumarin's phototoxicity, and how it connects to coumarin?

Thanks as always for generously sharing your knowledge!

Kim said...

In this post, you write that coumarins "can reduce water retention" Did you mean increase water retention? If it does decrease water retention, should we not be using ingredients that contain this?

Susan Barclay-Nichols said...

HI Kim. As I mentioned in the other post in which you posed this question, it means water retention in the sense of feeling bloated. I consider this to be a good thing.