The most prominent role of vitamin C is its immune-stimulating effect, e.g., important for defence against infections such as common colds. It also acts as an inhibitor of histamine, a compound that is released during allergic reactions. As a powerful antioxidant it can neutralize harmful free radicals and it aids in neutralizing pollutants and toxins. Thus it is able to prevent the formation of potentially carcinogenic nitrosamines in the stomach (due to consumption of nitrite-containing foods, such as smoked meat).
Importantly, vitamin C is also able to regenerate other antioxidants such as vitamin E. Vitamin C is required for the synthesis of collagen, the intercellular "cement" substance which gives structure to muscles, vascular tissues, bones, tendons and ligaments. Due to these functions, vitamin C – especially in combination with zinc – is also important for the healing of wounds.
In addition, vitamin C contributes to the health of teeth and gums, preventing haemorrhaging and bleeding. It also improves the absorption of iron from the diet. vitamin C is also needed for the metabolism of bile acids which may have implications for bloodcholesterol levels and gallstones. Moreover, vitamin C plays an important role in the synthesis of several important peptide hormones, neurotransmitters and carnitine.
Vitamin C is also a crucial factor in the eye's ability to deal with oxidative stress, and can delay the progression of advanced age-related macular degeneration (AMD) and vision-loss.
In a nutshell, the main functions of vitamin C are: