Poor diet and mental health problems linked in teenagers: Study

By Dr. Ananya Mandal, MDSep 26 2011

Teenagers who eat healthy diets including fruits and vegetables have lower rates of mental health problems, a study shows. A study of 3,000 adolescents has found that those who had poor diets filled with junk and processed foods were more likely to suffer mental health problems such as depression and anxiety.

One in five Australian adolescents has some form of mental health problem. Genes and environmental factors such as stressful events in early childhood are already known to play a role.

While other studies have shown links between diet quality and mental health disorders in adults, the new research is the first to demonstrate the link in adolescents. Dr Felice Jacka, from Deakin University's Barwon Psychiatric Research Unit, said the finding suggested it could be possible to stop some mental health problems developing in adolescents by ensuring they ate healthy diets. Dr Jacka's study was published on Thursday in the journal PLoS One.

“The results of this study are consistent with what we have seen in adults but we think it could be more important because three quarters of psychiatric illnesses start before adulthood and once someone has depression they are likely to get it again,” Dr Jacka said. “If you can prevent it before it starts in childhood and adolescence you are shutting the gate before the horse bolts. Having good nutrition-rich foods is really important for adolescents because it's a time when they are growing rapidly and it's essential they have adequate nutrition.”

In her study Dr Jacka analyzed data from more than 3,000 Victorian adolescents aged 11 to 18. The participants filled in questionnaires about their diets and psychological symptoms in 2005 and again in 2007. Those who ate healthy diets in 2005 were found to have fewer mental health problems than those with poor diets. Those who improved their diets by eating more healthy foods between 2005 and 2007 also had better mental health than those who had an unhealthy diet during that period.

Other factors that could be associated with diet quality and mental health - such as the adolescent's socio-economic status, age, gender, exercise levels and weight - were also taken into account but were not found to have any effect on the results.

Dr Jacka said parents could protect children against mental health problems by following national guidelines for eating two serves of fruit and five serves of vegetables a day, as well as sticking to whole grains and lean meats while avoiding junk food. But she said it was also vital for government restrictions on the access to and marketing of junk foods. “We know depression and anxiety have a very early age of onset and they are common in adolescents and it looks like quality of their diets could be linked to a risk of mental health problems,” she said.

“The results suggest we shouldn't just be looking at obesity as a potential outcome of poor diet, we need to look at mental health and physical health as potential outcomes,” she concluded.