At least one-third of early deaths could be prevented if everyone moved to a vegetarian diet, Harvard scientists have calculated. Dr Walter Willett, professor of epidemiology and nutrition at Harvard Medical School said the benefits of a plant-based diet had been vastly underestimated. Looking at the question of how much could we reduce mortality shifting towards a healthy, more plant based diet, not necessarily totally vegan ... our estimates are about one third of deaths could be prevented," [he said]. "That's not even talking about physical activity or not smoking, and that's all deaths, not just cancer deaths. That's probably an underestimate as well as that doesn't take into account the fact that obesity is important and we control for obesity." Dr Neal Barnard, president of the Committee for Responsible Medicine also said people need to wake up to the health benefits of vegetarianism and veganism. "I think we're underestimating the effect," he told delegates. "I think people imagine that a healthy diet has only a modest effect and a vegetarian diet might help you lose a little bit of weight. But when these diets are properly constructed I think they are enormously powerful. A low-fat vegan diet is better than any other diet I have ever seen for improving diabetes. With regards to inflammatory diseases like rheumatoid arthritis we are seeing tremendous potential there too. Partly because of things we are avoiding and cholesterol but also because of the magical things that are in vegetables and fruits."