THE NAD+/NADH TEST

NAD detection is based on an enzymatic reaction that is coupled to a color change, which is measured photometrically. The NAD+ and NADH molecules extracted from the blood sample and stabilized separately are mixed with NAD-dependent enzymes. In addition to the concentrations of NAD+ and NADH in the blood, the ratio of oxidized to reduced NAD is also calculated.the NAD+/NADH ratio regulates glucose and fatty acid degradation via NAD+-dependent enzymes in glycolysis in the cytosol and the citric acid cycle in the mitochondria and the subsequent NADH-dependent energy production in the mitochondria. It is speculated that the activity of sirtuins may also depend on the balance of the redox pair, as they are only fully active above a certain amount of NAD+ and are inhibited by extremely high NADH concentrations. In resting cells, which obtain their energy mainly from oxidative metabolism, the NAD+/NADH ratio is relatively high. It decreases both with an NAD+ deficiency and with an NADH excess, with both conditions being detrimental to health. NADH accumulates when the mitochondrial respiratory chain is impaired or oxygen is missing as an end electron acceptor. This occurs, for example in diabetes, when the mitochondria are overloaded by the high amounts of glucose. Cancer cells that switch to anaerobic energy production also have a low NAD+/NADH ratio. The accumulation of NADH blocks the citric acid cycle via a feedback mechanism, inhibits nucleotide and protein synthesis and thus impairs cell growth.