Jayna posted an intriguing comment on our article on Osmosis Replenish, questioning why this serum would contain both niaciamide and resveratrol, since niacinamide negates the action of sirtuins (enzymes activated by resveratrol). I decided to do some digging around on niacinamide and found myself neck-deep in conflicting information on the antiaging role of niacinamide and beauty websites warning us not to use niacinamide with "sirtuins products"or to incorporate a niacinamide potion such as Olay into a regime that also includes Avon, a sirtuin cream. And then niacinamide is a liver toxin to boot. Oh dear. But before I trash my bottle of Osmosis (which I am liking very much), some Truth In Aging perspective is needed.

Niacinamide is also known as nicotinamide and nicotinic acid amide, the amide of nicotinic acid, which is vitamin B3 (also known as niacin). Topical application of Niacinamide has been shown to increase ceramide and free fatty acid levels in skin, prevent skin from losing water content, decrease hyperpigmentation and stimulate microcirculation in the dermis, according to many peer published studies. So what's not to like?

Well, there are a few controversies surrounding Niacinamide. I'll try to deal with the sirtuins issue first. For a start, there are no such thing as "sirtuins" creams, despite the best endeavors of sites such as FutureDerm to convince us otherwise. Sirtuins is not an ingredient and isn't in creams. Sirtuins are enzymes in the body that certain ingredients in creams may be able to activate.

The main role of sirtuins is to regulate the activity of the genes responsible for metabolism, cell defense and reproduction. When food is scarce, the body’s sirtuins go into self-preservation mode. What if you could activate sirtuins without starving yourself? Talk about having your cake and eating it too. A sirtuin activator has been found in the form of resveratol, found in grapes and already known to be an effective antioxidant.

The belief that niacinamide and sirtuins or resveratrol should be kept apart at any cost seems to stem from some theories about niaciamide that are far from clear cut. NAD is the abbreviation used for Nicotinamide Adenine Dinucleotide (NAD), the biologically active coenzyme form of vitamin B3 (niacinamide). It was recently discovered that sirtuins are dependent on NAD, but there seems to be confusion over whether that is a good or a bad thing.

The most cited anti-niacinamide study is one from 2005. However, it says that niacinamide/nicotinamide is a sirtuins regulator (not quite the same thing as an inhibitor). Another study from 2008, says nicotinamide is a sirtuins inhibitor, but that it also increased one of the components in sirtuins (also called SIR2) and may be helpful against Alzheimer's. In 2006, a Cornell University team wrote: "In light of their protective effects, sirtuins and NAD+ metabolism could represent therapeutic targets for treatment of acute and chronic neurodegenerative conditions" and added that we need "new insights into mechanisms by which NAD+ metabolism regulates sirtuin activities in cells'.

It seems to me that the research is very nascent and the interaction of SIR2 and nicotinamide is barely understood. At this stage, trying to eliminate vitamin B3 from your diet (as some dedicated long lifers do) or avoiding cosmetic combinations of niacinamide and resveratrol are a bit like adding two and two together and making seven.

Having got all that out of the way, is niacinamide toxic? It seems that it can damage the liver if large quantities are taken orally and that this outcome is rare. Concerns about carcinogenity seem to date back to decades-old studies and the modern consensus seems to be that niacinamide inhibits several carcinogens.

So all in all, I'll keep using my Osmosis Replenish.