In laboratory experiments, a team at the University of Glasgow simulated what happens in the human stomach. They found vitamin C (ascorbic acid) mopped up potential cancer-causing compounds that are made when saliva and food mixes with stomach acid. But when they added fat to the mix, the ascorbic acid could no longer convert the hazardous compounds into safe ones. Antioxidants like ascorbic acid protect against the formation of (carcinogenic) nitrosocompounds by converting the nitrosating species into nitric oxide. However, when fat is present, it reacts with the nitric oxide to reform nitrosating species, the scientists found. Bridget Aisbitt, nutrition scientist for the British Nutrition Foundation, said: ... "This research is interesting. She said fat-compatible antioxidants in the body, such as beta-carotene, could also neutralise the nitrosocompounds. This is another reason to underline the importance of a healthy balanced diet where meals high in fat should not be frequent and five portions of fruit and vegetables - our main source of vitamin C - are eaten each day.