I’ve been a loyal reader of your blog for quite some time and enjoy the reliable advice you give as a professional. Therefore I would like your opinion on something that has been bothering me for a while.
I’m an avid user of fake tan (wear it basically all the time) and lately I’ve seen more and more formulas containing DMI (dimethyl isosorbide) as an “accelerator” or skin penetration enhancer. This promotes the absorption of DHA into the skin.
Now my question is whether this DMI also takes the DHA deeper into the skin and possibly even into the bloodstream. The reason I’m asking this is the fact that there have been a few scientific studies that have shown a link between DHA and free radicals or DNA damage. This worries me a bit and makes me wonder whether I should avoid fake tan products containing DMI.
Thanks a lot and keep up the good work!
Hope to hear from you soon,
Hello Charlene. This question took me on a trip down memory lane. I once had the job of transferring a pharmaceutical product from the US to the European market. This had a patent on the use of DMI to reduce irritation. It worked by slightly dissolving the anti-acne ingredient on the skin which made it less likely to cause the skin to be damaged. I remember spending many hours looking down a microscope trying to get impressive looking pictures of crystals dissolving to prove the point.
As part of the same project we ended up as the first people who submitted a drug application to the health authorities containing DMI. We had to put together a huge pack of data to demonstrate its safety. I can therefore very easily put my hand on my heart and say that this material is safe. It would surprise the average chemist if it had turned out to be a problem. It is a simple sugar molecule slightly modified, so even without studying it carefully you’d be inclined to imagine it is safe enough.
But your question was to do with its effect on the penetration of DHA into the skin and possibly the bloodstream. I would be very surprised indeed if this were the case, if only for the fact that DMI does indeed seem to have the effect of enhancing the tanning effect of DHA. I am not entirely convinced of the explanation that it does so by enhancing the skin penetration. Enhancing skin penetration is not at all an easy thing to do. This is particularly true of a molecule like DHA which is very reactive. You have two problems here, getting it through the skin and stopping it from reacting while it is going through.
The tan is produced by the DHA reacting in the skin. As soon as it does so it is no longer available to get through the skin. If you are getting more tanning in the presence of DMI I would say that this indicates that the DHA is being slowed down in its progress through the skin rather than speeded up. If it is has caused a tan, it can’t be getting through.
But even if DMI does lead to more DHA getting through the skin I doubt very much it would do very much harm when it got there. Free radicals are generated in most chemical reactions, and the body has plenty of defences against the damage caused by free radicals. The biggest source of free radicals in the skin is exposure to light, and your body fights a continual battle against this source, a battle which requires it to generate antioxidants and deploy them where they are needed. That is why a third of the vitamin E in the body, which is its workhorse antioxidant, is found in the skin.
Compared to that huge daily burden dealing with the small quantity of DHA that gets through the skin from self tans is a trivial matter.