A lack of THESE micronutrients could contribute to bad behaviour in boys
New research has found that a deficiency of iron and vitamin B12 in young boys around age 8 could be linked to behaviour problems later in childhood.
Led by the University of Michigan School of Public Health, USA, the new study set out to assess whether levels of iron, blood concentrations of zinc, folate, vitamins A and B12, and anemia were associated with behaviour problems in 1,042 children age 5-12 in Bogotá, Colombia.
The researchers looked at both internalising behaviours, such as anxiety and depression, and externalising behaviours, such as being aggressive and breaking rules.
The team took blood samples to measure levels of the micronutrients and conducted an in-person follow-up assessment with around one-third of the participants after six years, using a questionnaire to assess behaviour.
After taking into account other factors such as age at the start of the study, time spent watching television or playing video games, and socioeconomic status, the results showed that iron deficiency, anemia and low plasma vitamin B12 levels in boys at around age 8 were associated with 10% higher mean scores on the questionnaire for externalising behaviours, with iron deficiency also related to a 12% higher score for internalising problems.
"Iron deficiency is still highly prevalent in many regions worldwide," commented senior author Eduardo Villamor. "There is less data on vitamin B12 deficiency but available evidence also suggests it may be a substantial public health problem in certain populations."
Villamor added that the findings could also be relevant to other populations and that fortunately, correcting a deficiency may not always be complicated.
"In our study population, for example, we showed before that a school snack programme increased vitamin B12 blood levels after three months."
Previous research on infants has also found a link between iron deficiency and subsequent behaviour problems, however no known research had studied the effects of these micronutrient deficiencies in older children.
As to why the deficiencies may affect behaviour, Villamor explained that some parts of the brain develop during childhood, and as these brain regions respond to environmental conditions at different life stages they could be involved in the development of behaviour problems.
The researchers found no associations among girls, with Villamor commenting that "we don't have a clear explanation of why there were sex differences, although we knew it was important to study boys and girls separately because they may differ in the timing of development."
"Studies in rats have found that some micronutrient deficiencies affect male and female brains differently but it is not clear exactly why this may also be the case in humans."
The results can be found online in the Journal of Nutrition.