Vitamin C is made naturally in almost all living animals except humans, primates and guinea pigs. Dogs and cats produce their own vitamin C from ingested food that have metabolized into glucose. Humans must consume vitamin C from its food sources, or they risk severe health problems. There is an intimate relationship between glucose and vitamin C that has a dramatic impact on immunity and overall cellular health.
Most animals and plants are able to synthesize their own vitamin C. This is done through a biochemical pathway that depends on 4 key enzymes which convert glucose to vitamin C. In mammals, the glucose is extracted from stored sugar (glycogen) and the transformation into vitamin C is produced in the liver.
Humans lack the L-gulonolactone oxidase enzyme that is critical for the last step of vitamin C synthesis. Humans require a good amount of vitamin C in order to build healthy tissue collagen and promote strong immune function.
When low levels of vitamin C are present, the body makes due by recycling the oxidized version of vitamin C. This redox cycling is performed by the master anti-oxidant glutathione. As long as enough glutathione is present, the vitamin C redox cycle can continue.
In the 1970's, Dr. John Ely discovered the Glucose-Ascorbate-Antagonism (GAA) theory. Glucose and vitamin C (ascorbate) have a very similar chemical makeup. This theory proposes that elevated glucose levels compete and effectively restrict vitamin C from entering cells. Both glucose and vitamin C depend upon the pancreatic hormone insulin and its signaling effects in order to get into cells.
The GLUT-1 Receptor
There is an important receptor called the Glut-1 receptor that activates in response to insulin to allow both glucose and vitamin C to enter the cell. However, glucose has a greater affinity for the insulin receptor. This means that the greater the content of circulating blood sugar the less vitamin C will enter the cell.
White blood cells have more insulin pumps than any other type of cell and may contain 20 times the amount of vitamin C as other cells. They also need 50 times more vitamin C inside the cell than in the blood plasma in order to handle the oxidative stress that occurs when they encounter a pathogenic substance.
Elevated Blood Sugar Hinders Phagocytic Ability
When white blood cells encounter pathogenic bacteria and viruses, they must ingest or phagocytize these organisms in order to neutralize them. The phagocytic index measures how effective a particular white blood cell is at destroying viruses, bacteria & cancer cells. Elevated blood sugar impairs this phagocytic index. In fact, a blood sugar of 120 reduces the phagocytic index by 75%.
Glucose and ascorbic acid also work on the hexose monophosphate (HMP) shunt. The HMP is a biochemical pathway that produces NADPH. White blood cells need NADPH to create superoxide and other reactive oxygen species that oxidize and destroy pathogens. Vitamin C not only helps produce NADPH, but also regulates quantities so the white blood cell does not create too much oxidative stress in its attempt to protect the body.
Vitamin C activates this important shunt while glucose inhibits it. This HMP shunt also produces ribose and deoxyribose, which provide important raw materials for the formation of new white blood cell RNA/DNA. When the immune system is under attack, it needs to quickly produce new immune cells. If blood sugar is high enough to turn off the HMP shunt, it will reduce the quantity of RNA/DNA and the amount of new immune cells formed.
About the author: Dr David Jockers is a Maximized Living doctor and owns and operates Exodus Health Center in Kennesaw, Georgia where he specializes in functional nutrition, functional medicine and corrective chiropractic care to get to the underlying cause of major health problems.
His website features great articles on natural health and incredible recipes. He is the author of the best-selling book SuperCharge Your Brain - the complete guide to radically improve your mood, memory and mindset. He has over 36,000 active followers on his social media and email newsletter and is a big influencer in the Primal Health movement.
Dr. Jockers is also available for long distance consultations and health coaching to help you beat disease and reach your health goals. For more information got to www.drjockers.com