How does vitamin C protect us from cancer?
Compounds known as Michael acceptors are potentially dangerous to living organisms. This is because they undergo conjugate addition: By this mechanism, Michael acceptors attack enzymes, particularly DNA polymerase, which is vital in DNA replication. Any compound that is good at conjugate addition is probably toxic and carcinogenic. Most Michael acceptors damage the DNA replication process unselectively. However, we are protected from this by glutathione, a compound present in most tissues: Glutathione is a tripeptide. The thiol (SH) group of glutathione scavanges carcinogenic compounds by conjugate addition: If glutathione, which is naturally abundant in the body, is removed by oxidation and can no longer scavenge toxins, then the organism is in danger. Vitamin C removes stray oxidising agents therefore protecting the supply of glutathione. This is one reason why vitamin C is so beneficial to humans.
