But now it seems they may have the last laugh, with research showing vegetarians are more intelligent than their meat-eating friends.

A study of thousands of men and women revealed that those who stick to a vegetarian diet have IQs that are around five points higher than those who regularly eat meat.

Writing in the British Medical Journal, the researchers say it isn't clear why veggies are brainier - but admit the fruit and veg-rich vegetarian diet could somehow boost brain power.

The researchers, from the University of Southampton, tracked the fortunes of more than 8,000 volunteers for 20 years.

At the age of ten, the boys and girls sat a series of tests designed to determine their IQ.

When they reached the age of 30, they were asked whether they were vegetarian and their answers compared to their childhood IQ score.

Around four and a half per cent of the adults were vegetarian - a figure that is broadly in line with that found in the general population.

However, further analysis of the results showed those who were brainiest as children were more likely to have become vegetarian as adults, shunning both meat and fish.

The typical adult veggie had a childhood IQ of around 105 - around five points higher than those who continued to eat meat as they grew up.

The vegetarians were also more likely to have gained degrees and hold down high-powered jobs.

There was no difference in IQ between strict vegetarians and those who classed themselves as veggie but still ate fish or chicken.

However, vegans - vegetarians who also avoid dairy products - scored significantly lower, averaging an IQ score of 95 at the age of 10.

Researcher Dr Catharine Gale said there could be several explanations for the findings, including intelligent people being more likely to consider both animal welfare issues and the possible health benefits of a vegetarian diet.

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