Posted Aug 28, 2009
The Western diet is associated with mental health issues among teenagers, a study published in Preventative Medicine has found. While the idea is hardly new, the research examined 1600 Western Australian teenagers, the first time that the whole diets of teenagers have been assessed against their mental health.
Lead author Dr Wendy Oddy of the Telethon Institute for Child Health Research acknowledges that many questions remain unanswered. One of these is the direction of causation – do people eat bad food because they are depressed, or depressed because they eat badly? “We can’t answer that with this data, but we have a grant to follow up the sample group over time,” Oddy says.
Likewise there is a strong relationship between obesity and mental health issues, but as yet the data do not reveal which comes first. However, Oddy says that “nutrients affect brain function, so it is biologically plausible this is from energy-dense foods pushing nutrients out of the diet”.
Participants in the study were asked to rate how often they ate certain foods, and to estimate helping sizes. The 212 foods were grouped into 38 categories and tested against a range of mental health indicators.
Foods considered healthy, such as fresh fruit, vegetables and wholemeal cereals, were associated with lower rates of mental illness symptoms, although in many cases the associations were not statistically significant. Red meat and confectionary showed significant associations with poor mental health outcomes, and this was also observed for the highest consumers of takeaway foods. Non-significant negative outcomes were observed for soft drink, refined grains and chips.
These results applied after controlling for factors such as sedentary behaviour and parental income and education. The correlation was stronger with externalising factors such as temper tantrums, aggression and even lying than internalising factors such as anxiety.
Oddy is reluctant to lay social violence on diet’s door but says: “If you take out all the other factors such as social conditions there may be a small contribution. Then again there is evidence that healthy diets in prison cafeterias can ameliorate prison violence.”
Oddy says there are many possible explanations. “Antioxidants in fruits and vegetables protect against cell damage; high levels of glucose cause rapid mood swings. There’s also evidence essential fatty acids may contribute to mental health.”
Date: Aug 24, 2009
