Consumption of an unhealthy Western diet characterized by meat, hamburgers, chips, and soft drinks, may reduce the volume of the left hippocampus (related to depression), whereas a healthy diet of fresh vegetables and fish may increase hippocampal volume.

In a study of more than 250 individuals, investigators found that during a period of 4 years, there was a difference of more than 200 cubic millimeters in hippocampal volume between individuals who ate a healthy diet and those who consumed an unhealthy diet.

"To our knowledge, this is the first human study to demonstrate associations between diet and hippocampal volume concordant with data previously observed in animal studies," investigators led by Felice N. Jacka, PhD, associate professor in the Division of Nutritional Psychiatry Research at Deakin University, Geelong, Australia, and president of the International Society for Nutritional Psychiatry Research, write.

"These findings suggest the potential for dietary interventions to promote hippocampal health, decrease age-related atrophy, and prevent negative health outcomes associated with hippocampal atrophy," they add.

The research was published online on September 8, 2015 in BMC Medicine.