How Does Sugar Depress the Immune System?

I have taught my patients and young athletes for the last fifteen plus years that sugar depresses the immune system and increases their chances of manifesting an infection, as well as accelerating the aging process and increasing the risk of every chronic illness.  How does this happen?  There are at least a couple of known mechanisms by which sugar depresses the immune system.

First, when blood sugar rises, the pancreas secretes the hormone insulin into the blood stream.  Insulin has many effects in the body, just one of which is to stimulate the stress response, which leads to increased stress hormone (cortisol and catecholamines) production.  Stress hormones down regulate the cell mediated immune system to conserve energy needed for the response to stress.

The second mechanism has to do with the fact that the sugar molecule, glucose, and Vitamin C are almost identical.  In fact, Vitamin C is made in almost all living mammals, except humans and a couple of other species, from glucose.  The problem is that since they are so similar, they both use the same cell membrane receptors to enter the cell.  Thus, Vitamin C and glucose compete with one another to enter the cell.  Consequently, a high concentration of blood glucose, particularly from refined sugars and grains, leads to glucose taking up most of the receptor sites.  The phagocytic cells of the immune system (the ones that gobble up foreign invaders like viruses and bacteria) require high amounts of Vitamin C to work properly.  A blood sugar value of 120 reduces the phagocytic index by 75%.  One saltine cracker will cause blood sugar to go over 100, and in many people it will cause the blood sugar to go to 150 for a variety of reasons.

In case you are wondering, the answer is not to take high doses of Vitamin C supplements, which can be associated with its own set of problems.  The rational answer is to reduce the toxic levels of sugar in the diet and get adequate  amounts of Vitamin C from whole foods, which is what I teach in adopting The Innate Diet.