Difference Between NAD+, NADH and NADPH


What is NAD+?

NAD+ is the abbreviated symbol for Nicotinamide Adenine Dinucleotide. It is a coenzyme present in biological systems. NAD+ is involved in the metabolism specifically in redox reactions. NAD+ contains a positive charge and, therefore, has the ability to oxidize other biological compounds. It accepts electrons from other molecules and become reduced. This reaction is called an electron transfer process and could be shown as below;

NAD+   +    H+    +    2e          →              NADH

NAD+ has been found to be a substrate to enzymes that add or remove functional groups from proteins. This nature is exploited in research related to drug discovery. In organisms,  NAD+ is synthesized from starting materials aspartate and tryptophan (Trp). It is also synthesized by modifying the more complex compounds such as niacin taken through the diet. Sometimes NAD+ is converted to NADP+ and once this transformation is done the metabolic role changes.

What is NADH?

NADH is the reduced form of NAD+. Similar to NAD+, NADH also participates in metabolic processes when reduction is necessary. When NADH reduces a compound, it gets oxidized to NAD+. The alternating oxidation and reduction of these two compounds is observable in many metabolic pathways such as citric acid cycle. In diet, NADH is rich in animal proteins. Therefore, vegetarians may sometimes have to take NADH supplements.  NADH is a cofactor of the alcohol dehydrogenase enzyme. It helps protect liver from alcohol damage.  NADH also lowers cholesterol and blood pressure. NADH has also found to enhance immunity and improve memory. However, its main biological role is to act as a coenzyme.

What is NADPH?

NADPH stands for Nicotinamide Adenine Dinucleotide Phosphate. It was also known as TPN back in times which stood for triphophopridine nucleotide. NADPH is a coenzyme which is used in anabolic reactions. It is used in lipid and nucleic acid synthesis as a reducing agent. This differs from NADH due to the additional phosphate group at 2nd position of the ribose ring in the adenine moiety. Pentose phosphate pathway is the main generator of NADPH. In mitochondria, NADPH is made from NADH using NADH kinase enzyme. In plants,  NADPH is produced by ferrodoxin-NADP+ reductase in the last step of light reaction of photosynthesis.

What are the differences between NAD+, NADH and NADPH?




     Oxidized form of NADH

     Reduced form of NAD+

     Contains an additional phosphate group than the NADH

     Acts as an oxidizing agent

     Acts as a reducing agent

     Acts as a reducing agent

     Participates in catabolic reactions

     Participates in catabolic reactions

     Participates in anabolic reactions

     The additional phosphate group is a bio-label that helps to identify that this should be used for anabolic reactions

     Involved in electron transfer    processes

     Involved in electron transfer processes

     Involved in lipids and nucleic acid synthesis

     Produced by Starting materials tryptophan and aspartic acid

     Produced by aspartic acid and tryptophan as starting material

     Produced by Pentose phosphate pathway, NADH phosphorylation, and in light reaction in plants

  • jules105

    Should I buy NADH or NAD+ supplement for improved health and anti-aging? Is it true that NADH supplements are almost ineffective? Thank you.