From a brief article at Barry Groves’ Trick and Treat blog:
Scientists at the Department of Physiology, Anatomy and Genetics, University of Oxford, have discovered that going veggie could be bad for your brain – with those on a meat-free diet six times more likely to suffer brain shrinkage.
The study involved tests and brain scans on community-dwelling volunteers aged 61 to 87 years without cognitive impairment at enrolment, over a period of five years. When the volunteers were retested five years later the medics found those with the lowest levels of vitamin B12 were also the most likely to have brain shrinkage. It confirms earlier research showing a link between brain atrophy and low levels of B12.
Vegans are the most likely to be deficient because the best sources of the vitamin are meat, particularly liver, milk and fish.
This study confirms other findings, covered in Trick and Treat, which shows that overall human brain sizes have reduced by an average 11% since we adopted an agricultural diet based on cereal grains rather than the meat-based diet of our Palaeolithic ancestors.
Vogiatzoglou A, et al. Vitamin B12 status and rate of brain volume loss in community-dwelling elderly. Neurology 2008; 71(11): 826-32.