Sugary, fatty foods shrink your brain

Unhealthy eating not only expands your waistline, it can shrink your brain.

Australian researchers have shown for the first time the part of the brain used for learning, memory and mental health is smaller in people with poor diets.

The study by Deakin University and Australian National University also suggests older Australians who drink sweet drinks, eat salty snacks and processed meats have smaller hippocampi.

Associate Professor Felice Jacka says while people typically worry about the affects of bad food on their waistline, the study shows brain health is also affected.

"It's becoming even clearer that diet is critically important to mental health as well as physical health throughout life," Professor Jacka said.

Researchers used magnetic resonance imaging to measure the hippocampi in more than 200 Australian adults, aged 60 - 64 years, and assessed their life-long dietary habits.

The study also found those who ate more nutrient-rich foods, such as vegetables and fish, had a larger left hippocampi.

The findings could provide further insight into the cause of dementia and mental health issues.

The study results are published in the journal BMC Medicine.