The most bizarre story in the media this week has to be the one suggesting that eating sweets in childhood causes violence in adults.
The story was based on a study just published in The British Journal of Psychiatry. The authors tested the hypothesis that excessive consumption of confectionery at age 10 years predicts convictions for violence in adulthood (age 34 years). Data from age 5, 10 and 34 years were used. Results showed that children who ate confectionery daily at age 10 years were significantly more likely to have been convicted for violence at age 34 years, a relationship that the authors say was robust when controlling for ecological and individual factors.
We all know that sweets aren’t very good for us. The evidence supporting the high consumption of sugars and sweets as a causative factor in dental caries is overwhelming. It has also been suggested that the additives used in brightly coloured sweets may be linked to hyperactive behaviour in children. However, the idea that eating sweets can induce violence is one I haven’t heard before.
Studies linking diet and behaviour are not new. The Oxford Durham study, published in 2005, found that supplementing the diets of children with developmental coordination disorder with fish oils produced significant improvements in reading, spelling and behaviour after 3 months of treatment. The magnitude of the differences between the placebo and treatment groups were, however, small.
There has also been recent interest in the diets of prisoners and the effects of supplementing such diets with extra nutrients. The Wellcome Trust in the UK is currently funding a three-year project into nutrition supplementation and behaviour among prisoners, following a pilot study in 2002 among 231 prisoners, which found that violent incidents while in custody were cut by around a third among those given supplements.
The trouble with behaviour is that there are multiple factors that can have an effect — genetics, social environment, and upbringing, to mention a few. There is also the fact that, of course, a correlation does not prove cause and effect – just because people who ate sweets as children were more likely to have been convicted for violence at age 34, does not mean that eating sweets caused the violence.
There may be some effects of diet on some aspects of behaviour but these are likely to be small and research into this is ongoing.
I’ll be watching with interest for more fascinating research into this whole topic.
Moore SC, Carter LM and van Goozen SHM (2009) Confectionary consumption in childhood and adult violence, British Journal of Psychiatry, 195: 366-367