"Junk" foods may affect aggressive behaviour and school performance

October 4, 2005

Dr. Stephen Schoenthaler, a Professor of Criminal Justice at the California State University in Stanislaus, has long argued that there is a link between a healthy diet and decreased aggressive behaviour, as well as with increased IQ and school performance.

Dr. Schoenthaler is well-known for a youth detention center study where violations of house rules fell by 37% when vending machines were removed and the cafeteria replaced canned food by fresh alternatives. He summarizes his findings by saying that “Having a bad diet right now is a better predictor of future violence than past violent behaviour.” In a very large test, Schoenthaler directed a study in meals at 803 New York City schools, in low-income neighbourhoods, finding that the number of students passing final exams increased by 16%.

Critics have questioned some of Dr. Schoenthaler findings, due to the lack of placebo control groups. However, more recent work by Dr. Bernard Gesch, a physiologist at the University of Oxford, has placed some of the work on a more scientific footing. Dr. Gesch found that nutrition supplements produced a 26% drop in violations of prison rules over a placebo, and a 37% decrease in violent offences. The Netherlands has embarked on a wider scale dietary research program in 14 prisons.

The short term behaviour consequences of ingesting sugar are well understood: an initial burst on energy, followed a sugar low in which your body produces adrenalin, which makes you irritable and explosive. However, Schoenthaler and Gesch suggest that there are long term impacts over and above the short term consequences of blood sugar variations.