A controlled study of rats that were traumatised in early life and went on to exhibit depressed or anxious behaviours found those that were fed lard-laced foods such as cake or pie reversed their stress levels.

"We asked the question, if you're stressed early in life and then you're given yummy food to eat does that reduce your behavioural deficit, and basically that's what we found," lead researcher Margaret Morris told AFP.

"The animals who'd been exposed to stress who were then given palatable food, junk food if you will, no longer looked anxious."

Morris and her University of New South Wales team simulated trauma by forcing two control groups of rats to endure lengthy periods of separation from their mothers.

One of the groups was fed an all-you-can-eat "cafeteria diet" of junk food, and the other more healthy foods, and then run through a stress-testing maze.

Morris said they noticed an effect similar to anti-depressant drugs on the stressed rats after they ate junk food.

"The deficit in stress hormone receptors in part of the brain that we saw in the stressed animals was reversed by the diet," she said.

But Morris warned against hasty conclusions, saying more work needed to be done on the benefit of other factors such as exercise or the social interaction around food.

"We wouldn't want to say go and eat comfort food because that's not very healthy, but if we can find out whatever it was that started that process in train and find some other way of doing that, that would be really useful."

"There might be a critical time in the brain of those animals that their mood pathways or their behaviour is being modulated, and (if we) just tickled it for a few weeks maybe we would get the same benefit without having to make them all obese," she added.

(c) 2009 AFP