It turns out vegetarians really are smarter. But maybe not because of what they eat. Bright children, evidently, are more likely to reject meat and opt to become vegetarians when they grow up, according to a study published in the BMJ (BMJ, doi:10.1136/bmj.39030.675069.55 published 15 December 2006).
Researchers from the University of Southampton who conducted the study suggest that vegetarians are more thoughtful about what they eat. But it remains unclear whether bright children choose to become vegetarians for the health benefits or for other reasons, such as a concern for animals, or as a lifestyle choice.
The scientists began investigating the link between IQ and vegetarianism because people with higher intelligence have a lower risk of heart disease, a curious observation. The benefits from vegetarianism are more obvious. A vegetarian diet is associated with a lower cholesterol level, lower blood pressure and less obesity – all risk factors for heart disease.
The study was based on more than 8,000 people born in 1970 whose IQ was measured at age 10. Now aged 36, the researchers found 366, just under one in 20, said they were vegetarians (a third of these ate chicken or fish but none touched red meat).
As well as being brighter, the vegetarians were better educated and of higher social class but the link with intelligence remained statistically significant even after adjusting for these factors. Despite their intelligence they were not wealthier and were more likely to be working for charities or in education. "It may be that ethical considerations determined not just their diet but also their choice of employment," the report said.
It report concludes: "Our finding that children with greater intelligence are more likely to report being vegetarian as adults, coupled with the evidence on the potential health benefits of a vegetarian diet, may help to explain why higher IQ in childhood or adolescence is linked with a reduced risk of coronary heart disease in adult life."