Vitamin C is essential for life, and humans obtain this nutrient exclusively through the diet. It functions inside the cells in our bodies, where it plays an important role in supporting many essential processes. In the past decade, we have learned a great deal about the myriad of biological roles assigned to this micronutrient and this information has given us new insight and understanding of its vital importance to health maintenance and disease prevention.
The bioavailability of vitamin C to the tissues is determined by absorption through the gut, active uptake into the tissues via the circulation and clearance from the kidneys. Tissue saturation is achieved with plasma vitamin C levels of around 80 µM, which is similar to the levels maintained in animals that are able to synthesise the vitamin. Recent evidence suggests that tissue saturation best supports a number of important cell functions, including the regulation of oxidative metabolism, cell stress responses, hormone synthesis, epigenetic regulation, and life and death signalling pathways.