Absorption of vitamin C from the human buccal cavity.

1. Ascorbic acid was absorbed across the mucosa of the human mouth. 2. Omission of sodium ions from the medium decreased the absorption of ascorbic acid. 3. The presence of D-glucose, or 3-O-methyl-D-glucose, increased the absorption of ascorbic acid but D-fructose had little effect and D-mannitol had no effect. 4. Calcium ions also increased ascorbic acid absorption probably by a secondary effect on "Na+ fluxes. 5. Buccal mucosa was also permeable to dehydroascorbic acid and D-isoascorbic acid.