Dr David Benton, of the department of psychology at Swansea University, who conducted the original study published in the Lancet, told the British Psychological Society conference that he was astonished by the reaction it provoked after it was publicised on the BBC programme QED. "The QED programme succeeded in emptying the shelves of vitamins," he said. "Lorry loads were coming in from the continent to replenish them, giving the world the unfortunate impression that British children were malnourished."
His study had shown that giving a supplement of 18 vitamins and minerals to children aged 12 to 13 over eight months boosted their non-verbal intelligence - the capacity for abstract reasoning and problem solving - by nine IQ points. In nine further studies, six showed a significant effect in all or some children. Closer analysis showed the supplements only helped children with blood levels of vitamins below 70 per cent of recommended daily allowances (RDA).
"Most children in Britain are well nourished and don't need vitamin supplements ... There are a minority of children whose diet is poor enough to benefit from these supplements."
Dr Benton said there were good biological reasons why improved nutrition should boost non-verbal IQ, which is associated with larger brain size. As nutrition has improved over the last 50 years, it has been reflected in increased height, larger brain size and rising IQ.
In a separate paper, Richard Lynn, Emeritus Professor of Psychology at Ulster University, told the conference intelligence had been rising by three IQ points a decade since the Thirties. "Improved diet is far and away the most important factor. We know brain size is a determinant of intelligence and it has increased in the last 60 years because of improved nutrition."
However, he said overall genetic intelligence had been declining because people lower down the social scale tended to have larger families while professional people had smaller ones. "The genetic component for higher intelligence is being passed on to fewer children," he said. This was reducing intelligence by one-half to two-thirds of an IQ point in each generation.
Professor Lynn was greeted by a handful of anti-Nazi protesters outside the conference who claimed his work was racist. He said that although environmental improvements in intelligence had outweighed the genetic deterioration, as nutrition improved to optimum levels it was possible that the genetic effects would result in a fall in intelligence in the future. There was no sign, however, that this had yet begun.Reuse content