I do not wish to get into a moral discussion about the rights or wrongs of eating animal produce, or to offend people who have strong ethical convictions against the consumption of animal products. I am speaking as a gastroenterologist, of 25 years experience. If you have a gut problem such as irritable bowel syndrome (IBS), then vegan diets can prove very problematic, vegetarian diets less so. Evidence also shows that vegan diets are not...