Fat intake may cut vitamin C benefits for the stomach

The research, performed by Emilie Combet and co-workers at the University of Glasgow, used a bench-top model of the human stomach to investigate the effect of vitamin C on the acidification of nitrite in the stomach, a process that can ultimately lead to the production of potentially carcinogenic N-​nitroso compounds. Presenting her findings at the annual main meeting of the Society for Experimental Biology, Combet revealed that vitamin C inhibited this conversion by approximately 99.7 per cent, thereby offering potential protection from stomach cancer-causing compounds. The image of vitamin C supplements with consumers is already strong. According to Frost & Sullivan, the US market generated $151.7m (€127.4m) in 2005. In Europe, revenue was calculated at $160.3m (€134.6m) for 2005, and is expected to grow to $192.5m (€161.6m) by 2011. However, when lipid (10 per cent) was also added to the gastric mix, the protective effects of vitamin C were blunted, and N-​nitrosamine was formed. "The generation of nitric oxide by the ascorbic acid and its rapid diffusion to the lipid compartment, where it reacted with oxygen to form [the nitrosative species] N2O3, which triggered the formation of N-nitrosamines,"​ stated Combet. "These results indicate that the presence of lipid can markedly alter the protective effects of antioxidants with respect to potentially carcinogenic nitrosative chemistry occurring in the human stomach, and illustrate how a diet rich in lipid can directly influence gastric biochemistry,"​ she said. According to the European School of Oncology, stomach cancer is the fourth most frequent cancer worldwide, with 800,000 new cases diagnosed every year. Japan and Korea are reported to have the highest rates. Source: The Annual Main Meeting of the Society for Experimental Biology​ 2 April 2007, Talk number CSS24 - Antioxidants and Ageing "Diet, gastric nitrosation and stomach cancer" ​Authors: E. Combet, S Paterson and K.E.L. McColl