A supermarket' s dream perhaps, but a consumer' s nightmare. Although there appears to be no residual radiation on irradiated foods, the process itself creates highly reactive oxygen molecules - oxidants that are known to be at the root of heart disease and cancer. What' s more, irradiating food has also been shown to reduce its vitamin content by as much as 96 per cent, and make the essential fats in foods such as vegetable oils and nuts go rancid.