The original study, published last year, was "inaccurate and misleading", and may have influenced health policy decisions, and had a negative impact on patient welfare.
Dr Peter Garrard of the Cardiovascular and Cell Sciences Research Institute at St George's, University of London, said that taking B vitamins lowers blood levels of homocysteine, which is a risk factor for dementia. He said there was "first-rate scientific evidence" for the benefits of taking B vitamins, especially in people over the age of 70 who had noticed a decline in their cognitive abilities.
Researchers from Oxford University also criticised the original study, which had relied on data about vascular disease prevention rather than dementia, and had failed to match cognitive decline in untreated patients.
(Source: American Journal of Clinical Nutrition, 2015; 101(2): 414)