This is a different angle on Vitamin C I had never thought about. As the molecule is very close to glucose, vitamin C could take on the properties of glucose and be used by the body for energy as needed by our immune system to counter pathogens. On this alone, I have a newfound respect for vitamin C that goes beyond its usual association to being an antioxidant.
I have been monitoring my oxygen saturation every night for 3 years already, and I follow with interest the nightly spO2 charts (at 4 second intervals), and see the effects of phagocytosis by neutrophils and macrophages using respiratory burst, which consume plenty of oxygen that lead to sharp temporary drops in spO2. Even eosinophils consume large amounts of oxygen to produce ROS that spewed at larger pathogens. Energy is needed for these white blood cells to protect us from pathogenic insults, and it is plausible that vitamin C does as much as glucose does to provide an emergency boost to strengthen our immune system.
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