Absorption of vitamin C from the human buccal cavity

Abstract

I . 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-~-ghcose, increased the absorption of ascorbic acid but 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 D-fructose had little effect and D-mannitol had no effect.Investigations using in vitro techniques have revealed sodium ion-dependent active transport of L-ascorbic acid from the small intestine of the guinea-pig (Stevenson & Brush, 1969) and the human (Stevenson, 1974). Both species have a nutritional requirement for vitamin C.Transport of certain food sugars across human buccal mucosa in vivo shows stereospecificity. For the natural isomers D-glucose and D-galactose the transport is at least partly sodium-dependent (Manning & Evered, I 976).It was the purpose of the present study to investigate the buccal absorption in vivo of L-ascorbic acid and compare it with the results obtained from small intestine. Other workers have already shown that buccal mucosa is permeable to ascorbic acid (Odumosu & Wilson, 1971.L-Ascorbic acid, analytical grade (Fisons Scientific Apparatus Ltd, Loughborough, England), dehydroascorbic acid (INC Pharmaceuticals Inc., Cleveland, Ohio, USA) and D-isoascorbic acid, Na salt (British Drug Houses Ltd, Poole, Dorset), were dried overnight over desiccant under vacuum. Other compounds used were analytical grade when available.Buccal absorption was measured as follows: 25 ml sample of the ascorbic acid solution prepared in appropriate buffer solution was preincubated at 37" for 5 min. Then the solution was circulated inside the mouth by the tongue and cheeks about once a second for 5 min. The solution was expelled into a beaker and the mouth rinsed for 5 sec with 10 ml of preincubated buffer without added ascorbic acid. This was expelled into the same beaker and the volume made up to 50 ml with buffer solution. After mixing a portion was then centrifuged at 3000 g for 10 min to remove insoluble material. At the beginning of each experiment a buccal blank, consisting of 25 ml of buffer solution at 37" but without ascorbic acid, was circulated in the mouth for 5 min then treated as before. Modified Krebs-Ringer buffer at pH 6 in mM concentrations: NaCl, 118.5; KCl, 4.7; KH,PO,, 1.2; MgSO,, 1.2; sodium citrate, 1.8; Na,HPO,, 6.2. For experiments with sodium-free buffer the sodium salts were substituted by potassium salts. Calcium ions were omitted otherwise calcium phosphate was precipitated. For experiments in which calcium was added (2.6 mM) the KH,PO,, Na,HPO, and sodium citrate were omitted and glycylglycine (1.8 mM) added (Evered & Sadoogh-Abasian, 1979). L-Ascorbic acid, dehydroascorbic acid and D-isoascorbic acid were determined colori-

Ascorbic Acid a Universal Supplement that Mitigates Road Transportation Stress in Ruminants: A Review

“…Ascorbate anion is only 1.6% unionized at pH 6, this was the pH at which the buccal cavity was at the experiments when performed (Sadoogh and Evered, 1979). Furthermore, ascorbic acid is very soluble in water and poorly soluble in lipid.…”

“…It was also shown that the process was not stereo specific since the natural form, L-ascorbic acid, and unnatural D-isomer were transferred across buccal mucosa at similar rate. The absorption of the vitamin is not sex dependent and the absorption of ascorbic acid did not reach a maximum with increasing concentration of up to 20 M (Sadoogh and Evered, 1979). The transportation of vitamin C across the buccal mucosa was found to be enhanced by glucose; it was then taught that glucose provides an energy metabolite (Sadoogh and Evered, 1979).…”

“…The absorption of the vitamin is not sex dependent and the absorption of ascorbic acid did not reach a maximum with increasing concentration of up to 20 M (Sadoogh and Evered, 1979). The transportation of vitamin C across the buccal mucosa was found to be enhanced by glucose; it was then taught that glucose provides an energy metabolite (Sadoogh and Evered, 1979). It was subsequently observed that ascorbic is amongst the compounds absorbed from the human buccal cavity, in a similar way to absorption from the small intestine (Sadoogh and Evered, 1979).…”

Impact of Buccal Glucose Spray, Liquid Sugars and Dextrose Tablets on the Evolution of Plasma Glucose Concentration in Healthy Persons

“…Transcellular route (passing through the cell): The transport of food sugars across human buccal mucosa shows proven stereospecifity. For the natural isomers D-glucose and D-galactose the transport is at least partly sodium-dependent 8,9 . The presence of a specialized sodium ion dependent transport mechanism for D-glucose was found in the dorsum of the tongue and (with slower absorption) from the ventral surface of the tongue 10,11 .…”

Vitamin C

“…When dealing with oral mucosal tissues, vitamin C is easily absorbed by passive diffusion through the buccal mucosa [14]. It was found that the absorption of the ascorbic acid through the buccal mucosa and small intestine is nearly equal [120].…”