Each of the twenty patients that is randomised to L-arginine will be given a tin containing 1 kilogram of the food supplement L-arginine. They are to take a spoonful (three grams) of the L-arginine and dissolve it in a glass of sugar free cold drink of their choice such as orange or lemon squash. They are to take it before food three times a day. The twenty patient randomised to placebo will receive a tin containing one kilogram of placebo and the instruction is as for the L-arginine group.