Natalie wrote: Sorry, Limehouse. I know what a "healthy" diet is supposed to consist of. What I wanted to know was how the experts determined that it was the poor diet causing the poor performances and not the other way round, ie the poor performers tending to have poorer diets (perhaps because they lacked the earning capacity to afford sufficient nutritious food, or they may not have known or cared enough about eating sensibly).
There has been quite a lot of research done in this field recently. When a child in school is performing poorly and behaving badly enough to be examined by an educational psychologist, an IQ test often reveals a higher than average IQ that is not being nurtured either intellectually or nutritionally. A change in diet from sugar-rich foods to protein-rich foods seemed to imrpove concentration and performance. Of course, their are other factors that must be taken into account such as whether improved performance is related to the child being given more attention or more challenging work to do. I think there is convincing evidence to suggest that not everyone performs to the level of their measured IQ due to a variety of factors, including poor diet.
For more information, this website id very helpful: