Does junk food shrink your brain?

New research has shown for the first time that the part of the brain used for learning, memory and mental health is smaller in people with unhealthy diets.

The results of the study by researchers at Deakin University and the Australian National University (ANU) suggest that older Australians with unhealthy diets have smaller hippocampi - the hippocampus is a part of the brain believed to be integral to learning, memory and mental health. It has also shown that with healthier diets have larger hippocampi.

Associate Professor Felice Jacka, lead author of the study and researcher with Deakin University's IMPACT Strategic Research Centre in Geelong, said that as the negative impact of on the waistline of the population grows, so does the evidence suggesting that our is also affected.

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

"We've known for some time that components of diet, both healthy and unhealthy, have a rapid impact on aspects of the brain that affect hippocampal size and function, but up until now these studies have only been done in rats and mice. This is the first study to show that this also appears to be the case for humans."

The researchers used to measure the size of hippocampi (there are two in the brain – left and right) in Australian adults aged 60-64 years and participating in the PATH study - a large longitudinal study of ageing conducted at the ANU. They also measured the participants' regular diets and took into account a range of other factors that could affect the hippocampus.

The results of the study, now published in the international journal BMC Medicine, suggest that older adults who eat more unhealthy foods, such as sweet drinks, salty snacks and processed meats, have smaller left hippocampi. It also shows that older adults who eat more nutrient-rich foods, such as vegetables, fruits and fish, have larger left hippocampi. These relationships existed over and above other factors that may explain these associations, such as gender, levels of physical activity, smoking, education or depression itself.

These findings have relevance for both dementia and mental health, Associate Professor Jacka said.

"Mental disorders account for the leading cause of disability worldwide, while rates of dementia are increasing as the population ages," she said.

"Recent research has established that diet and nutrition are related to the risk for depression, anxiety and dementia, however, until now it was not clear how diet might exert an influence on mental health and cognition.

"This latest study sheds light on at least one of the pathways by which eating an unhealthy diet may influence the risk for dementia, cognitive decline and mental disorders such as depression and anxiety in older people.

"However, it also points to the importance of diet for brain health in other age groups. As the hippocampus is critical to learning and memory throughout life, as well as being a key part of the involved in , this study underscores the importance of good nutrition for children, adolescents and adults of all ages."


Explore further

Junk food may lead to mental health problems in children

More information: "Western diet is associated with a smaller hippocampus: a longitudinal investigation." BMC Medicine 2015, 13:215  DOI: 10.1186/s12916-015-0461-x
Journal information: BMC Medicine

Provided by Deakin University
Citation: Does junk food shrink your brain? (2015, September 11) retrieved 17 October 2019 from https://medicalxpress.com/news/2015-09-junk-food-brain.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
205 shares

Feedback to editors

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more