In a previous post (which garnered a little interest), Nicotinamide as anti-inflammatory and workout recovery supplement, I discussed the anti-inflammatory properties of nicotinamide (a form of vitamin B3) and the possibility of using it to help exercise recovery.
However, after delving a bit further I'm not so sure. The concentration of nicotinamide used in the referenced study ranged from 2 to 40 mmol/l (that's millimoles per liter). This concentration was used in human blood, so-called ex vivo - that is, the blood was from humans, but in a test tube.
The molar weight of nicotinamide is 122 g. (Source.) I referred to the use of 500 mg of the vitamin, so that equals about .004 mole (4 millimoles). As you can already see, we have a problem.
We assume that B3 will diffuse across the total body water. A 70 kg man has about 40 liters of body water. (Source.) So a 500 mg dose of nicotinamide will result in a concentration of around 100 micromolar, i.e. not even close to the amount the researchers used to dampen inflammation. You'd need about 20 times more to reach the experimenters lowest concentration of 2 millimolar. (And that concentration could very well be toxic.)
So maybe whatever effect 500 mg had was in my imagination.