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Nutraceuticals and Nanoparticles
Posted: August 28, 2007
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But let’s assume for a moment that we already have a yoghurt on the market containing the skin-essential molecules linoleic and/or linolenic acid. As the daily volumes of yoghurt consumed are bigger than that of a cosmetic cream, its dose has been reduced to 0.1%, but with a 125-ml pot, still 125 mg enters her body if we assume a specific density of 1 g/ml.
Uptake of essential elements from food is much higher than that percutaneously absorbed; I assume 50%, but it could be much higher. That would mean that 62.5 mg of linoleic acid penetrates into the bloodstream. If only 10% of that goes to the skin and the typical adult body is 1.8 m2 in surface area, this would equate to a level of 6.25 mg/18,000 cm2, which is 0.347 µg/cm2--substantially lower than the 100 µg/cm2 we found in the skin following topical application. But of course, I had to make quite a few assumptions. Even in the best-case scenario (100% uptake into the body, and 100% ends up in the skin), the answer is still only 12.5 µg/cm2--still eight-fold less than delivered via the topical route from a nonoptimized formulation.
Of course, you could increase the level of linoleic acid to 1% in the yoghurt in an attempt to beat the cream, but I think this example shows that if you apply your chemical to where it is needed most, you have a higher probability of success and that targeted application works to your benefit.
Topically applying a formulation is a form of targeted delivery. And nanoparticles are all about delivery, aren’t they? They have become a bit of a hype and every marketer wants to be able to claim the four letters N-a-n-o somewhere on the bottle--and for good reasons, by the way, because these little things have really shown that size does matter. They are small but their actions are large, if not immense. They seem to be able to do everything.
But unlike nutraceuticals, nanoparticles are not completely unknown to the public at large. Media have indicated that they are dangerous and should be handled with care. They have shown to penetrate skin--of course, otherwise they would not work--but the risks are actually minimal. A solid penetrates at a rate 10,000-fold slower than a dissolved molecule. So, what is the risk?