Bittersweet: people who love tonic water may have bigger brains

Brain size doesn’t just relate to how smart people are but also to how bitter they find tonic water, University of Queensland researchers have found.

UQ Diamantina Institute Postdoctoral Research Fellow Dr Daniel Hwang said it was the first time brain size and taste perception had been linked.

“Everyone wants to know why we like certain foods and why individuals have preferences for bitter or sweet tastes,” Dr Hwang said.

“It was unclear if brain size affected anything other than a person’s IQ, but now we can show it relates to how we perceive food and drink.

“Whether you enjoy tonic water or not, people with bigger brains typically find it less bitter.”

More than 1600 participants in Australia and America rated their perceived intensities of different sweet and bitter taste solutions.

The size of their brain was then measured using an MRI scan.

“We found that the left side of the entorhinal cortex, an area of the brain responsible for memory, odour and visual perception, was larger in people who found quinine to be less bitter," Dr Hwang said.

“Quinine is a key ingredient in tonic water and is commonly used to assess people’s response to a bitter taste.” 

Dr Hwang said the results increased understanding of the gustatory cortex, the part of the brain that processes taste signals and generates taste sensations.

“Our study is a step towards understanding exactly how the brain perceives taste,” he said.

“The findings have implications for improving dietary behaviour and treating eating disorders.

“By targeting specific areas in the gustatory cortex, we could treat eating disorders using methods such as transcranial magnetic stimulation, a non-invasive treatment currently used to treat mental illness.”

The study was a collaboration between UQ, the QIMR Berghofer Medical Research Institute and Monell Chemical Senses Center.

The research was published in Behavioural Brain Research.