NADH is a coenzyme that the body makes from vitamin B3 (niacin). As their name suggests, coenzymes help enzymes work properly; enzymes are proteins that act as catalysts to change other substances in the body, such as changing food into energy.
NADH is used by the brain to make certain neurotransmitters and stimulates the production of ATP, which helps release energy in cells. Since some researchers believe an ATP deficiency contributes to fibromyalgia, NADH has been suggested as a supplement that may lessen fatigue and boost energy [a Georgetown University Medical Center study showed that NADH significantly boosted energy levels in CFS patients].
(Source: Natural Treatments for Fibromyalgia: An A to Z Guide, by Kenna Simmons. An official publication of the Arthritis Foundation. To purchase, visit www.arthritis.org.)