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.
Recent figures from the Office for National Statistics suggested that around 24 per cent or 141,000 deaths each year in Britain were preventable, but most of that was due to smoking, alcohol or obesity.
But the new figures from Harvard suggest that at least 200,000 lives could be saved each year if people cut meat from their diets.
Speaking at the Unite to Cure Fourth International Vatican Conference in Vatican City, Dr Willett, professor of epidemiology and nutrition at Harvard Medical School said: “We have just been doing some calculations looking at the question of how much could we reduce mortality shifting towards a healthy, more plant based diet, not necessarily totally vegan, and our estimates are about one third of deaths could be prevented.
“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.
“When we start to look at it we see that healthy diet is related to a lower risk of almost everything that we look at. Perhaps not too surprising because everything in the body is connected by the same underlying processes.”
British-born Professor David Jenkins, of the University of Toronto, who is credited with developing the glycemic index which explains how carbohydrates impact blood sugar, also told the conference that the benefits of vegetarianism had been ‘undersold.’
Dr Jenkins said humans would do better following a “simian” diet, similar to lowland gorillas who eat stems, leaves, vines and fruits rather than a “paleo” or caveman diet, which cuts carbohydrates but allows meat.
His team recently teamed up with The Bronx Zoo in New York and travelled to central Africa to record the feeding habits of gorillas.
When they recreated the diet for humans – which amounted to 63 servings of fruit and vegetables a day – they found a 35 per cent fall in cholesterol, in just two weeks, the equivalent of taking statins.
“That was quite dramatic,” he said “We showed that there was no real difference between what we got with the diet and what we got with a statin.”
Around 17.5 million people eligible for statins to stave off heart disease, equating to most men over 60 and most women over 65. But many complain of side effects and stop taking the drugs.
Dr Jenkins added: “We’re saying you’ve got a choice, you can change your diet to therapeutically meaningful change or you can take a statin. Drug or diet.”
“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 which just aren’t in spam.”