FRIDAY, Sept. 7 (HealthDay News) -- In an aqueous setting, ascorbic acid in the stomach's gastric juice helps prevent the generation of carcinogenic N-nitroso compounds, which develop when nitrate in the saliva encounters the acidic stomach environment. However, when ascorbic acid is in the presence of a lipid in the stomach, it promotes nitrosation, research published online Sept. 4 in Gut suggests.
Emelie Combet, of the University of Glasgow in Scotland, and colleagues created a laboratory model of the gastroesophageal junction containing an aqueous phase, to which sodium nitrite was added, as well as a lipid at a ratio of 10:1 aqueous to lipid.
The investigators found that when lipid wasn't present, ascorbic acid converted nitrosating species to nitric oxide, reducing nitrosative stress. But "when 10 percent lipid was present, ascorbic acid increased the amount of N-nitrosodimethylamine, N-nitrosodiethylamine and N-nitrosopiperidine formed by approximately 8-, 60- and 140-fold, respectively, compared with absence of ascorbic acid," the report indicates.
"The lipid phase is able to convert the influence of ascorbic acid from one that protects against nitrosation to one that promotes it. This effect is likely to be due to the ability of the nitric oxide formed by ascorbic acid within the aqueous phase to regenerate nitrosative species by reacting with oxygen within the lipid phase," the authors write. "The transforming role of lipids is likely to be relevant to the in vivo situation as lipid is present in the proximal stomach for a considerable time after eating and is also an important component of the epithelial membranes."
Abstract
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