Further analysis of the results showed those who were brainiest as children were more likely to have become vegetarian as adults.
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.
However, these differences were not reflected in their annual income, which was similar to that of non-vegetarians.
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.