Although the study was conducted in adults over 60 years of age, the researchers believe that the findings are relevant for people of all ages, including children.
“We have 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,” said lead study author Felice Jacka, associate professor at Deakin University School of Medicine in Geelong, Australia.
“This is the first study to show that this also appears to be the case for humans,” Jacka said.
The researchers used magnetic resonance imaging to measure the size of hippocampi in adults aged 60-64 years, participating in a large longitudinal study of ageing conducted at the Australian National University.
The study suggests 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 findings have relevance for both dementia and mental health, Jacka said. “As the hippocampus is critical to learning and memory throughout life, as well as being a key part of the brain involved in mental health, this study underscores the importance of good nutrition for children, adolescents and adults of all ages,” she said. The study was published in the journal BMC Medicine.