Vitamin C mechanisms, so the presence of large quantities of sugar in the intestine can slow absorption. Ascorbic acid is absorbed in the body by both active transport and simple diffusion. Sodium-Dependent Active Transport—Sodium-Ascorbate Co-Transporters (SVCTs) and Hexose transporters (GLUTs)—are the two transporter proteins required for active absorption. SVCT1 and SVCT2 import the reduced form of ascorbate across plasma membranes. GLUT1 and GLUT3 are glucose transporters, and transfer only the dehydroascorbic acid (DHA) form of vitamin C. Although dehydroascorbic acid is absorbed in higher rate than ascorbate, the amount of dehydroascorbic acid found in plasma and tissues under normal conditions is low,
Vitamin C an article by Linus Pauling. Briefly, his position was that for optimal health, humans should be consuming at least 2,300 mg/day to compensate for the inability to synthesize vitamin C. The recommendation also fell into the consumption range for gorillas - a non-synthesizing near-relative to humans. A second argument for high intake is that serum ascorbic acid concentrations increase as intake increases until it plateaus at about 190 to 200 micromoles per liter (µmol/L) once consumption exceeds 1,250 milligrams. As noted, government recommendations are a range of 40 to 110 mg/day and normal plasma is approximately 50 µmol/L, so 'normal'