There have only been a couple/three formal dose-response studies, so it is difficult to determine the optimal dose. Because of this, we are currently comparing 10 vs. 20 mmol (as KNO3) in HF patients and 0.15 vs. 0.30 mmol/kg (from concentrated BRJ) in healthy older men and women.

In general, though, it seems that the standard "take two shots of Beet It! and call me in the morning" approach works just fine.

On a related note, despite what you might read various places there really isn't much, if any, good evidence that supplementing for multiple days provides any significant benefit. IOW, at least at this stage it seems to simply be an acute effect (in humans, anyway...rats could be different, but their nitrate/nitrite/nitric oxide metabolism is considerably different from that in people, making extrapolation of such studies to humans questionable).