Poor diet could be a risk factor for mental health problems in adolescence, say Deakin University health researchers.
In a study of 3000 Australian adolescents, published in the journal PLoS One
, the Deakin researchers revealed that diet quality predicted mental health in adolescents over time, suggesting that it might be possible to use diet to prevent mental health problems developing in the first place.
"We found that diet quality and mental health were linked, with healthier diets associated with better mental health in 2005 and also predicting better mental health in 2007. This relationship even persisted when mental health at the starting point was taken into account," said Dr Felice Jacka from Deakin University's Barwon Psychiatric Research Unit based at Barwon Health, who led the study.
"Three quarters of psychiatric illnesses begin before the age of 25 and the average age that depressive illnesses start is only 13 years old. Once an individual experiences depression, they are more likely to experience it again. We believe that diet may be an important environmental factor influencing the development of mental health problems during adolescence, when rapid growth makes good nutrition particularly important.
"This new evidence suggests that it might be possible to prevent some cases of depression developing in the first place by ensuring that the diets of adolescents are sufficiently nutritious."
For the study, the researchers analysed data collected from over 3000 Australian adolescents in 2005 and again in 2007.
Participants filled in detailed questionnaires about their normal diets and their psychological symptoms. Other factors which may be associated with both diet quality and mental health, such as the socioeconomic status of the family, age, gender, physical activity levels, dieting behaviours and weight, were also taken into account.
"Importantly, we found that changes in diet quality over time were linked to changes in mental health," Dr Jacka said.
"On average, adolescents whose diets improved over the two year period also experienced an improvement in mental health over that time, while those adolescents whose dietary quality deteriorated over a two year period experienced an associated deterioration in mental health. This wasn't explained by changes in physical activity levels or weight."
The researchers also noted that the relationship didn't seem to work the other way.
"We also examined whether the relationships that we saw could be explained by 'reverse causality'; that is, was diet quality in adolescents a response to mental health symptoms rather than the other way around? We tested this idea, but did not find any evidence that this was the case," Dr Jacka said.
The results of the study can be found in the latest issue of the journal the journal PLoS One.