Researchers at the Centre de Recherche en Neuroscience de Lyon (CNRS/INSERM/Université Claude Bernard Lyon/Université Jean Monnet) and the Laboratoire Neuroscience Paris Seine (CNRS/INSERM/UPMC) believe they now know why.
Their results are published online on the Frontiers in Human Neuroscience website.
Genetic origin to aversion?
France has around 1,600 cheese varieties, yet there are those in France that can’t stand cheese.
The researchers studied a sample of 332 individuals to investigate if cheese is indeed the food that most frequently triggers aversion.
Among those with an aversion to cheese, 18% said they are intolerant to lactose. In 47% of these cases, at least one of their family members does not like cheese either. The researchers say that these figures suggest that there is a genetic origin to this aversion, which might be related to lactose intolerance.
To find out what happens in the brain, 15 people who like cheese and 15 who do not were selected and participated in a functional magnetic resonance imaging (fMRI) study. They were simultaneously exposed to the image and smell of six different cheeses and six other types of control foods.
They had to state whether they liked the smell and sight of the foods or not, and whether, at that moment, they wanted to eat them.
Observations on the brain
The researchers then observed that the ventral pallidum, a small structure usually activated in people who are hungry, was totally inactive while the smell and image of cheese was being presented to individuals with an aversion to cheese, whereas it was activated for all other food types.
Even more surprisingly, the researchers observed that areas of the brain, the globus pallidus and the substantia nigra, which participate in the reward circuit (which is activated when we love something), were more involved in people who do not like cheese than in those who do.
These structures may therefore also be triggered in response to an aversive stimulus. To explain this dual nature, the researchers suggest that these regions include two types of neurons with complementary activity: one related to the rewarding aspect of a food, the other to its aversive nature.
The work provides an insight into the areas of the brain that are activated when an individual is presented with an aversive food and suggests that the reward circuit may also encode disgust.
The Neural Bases of Disgust for Cheese: An fMRI Study. Jean-Pierre Royet, David Meunier, Nicolas Torquet, Anne-Marie Mouly and Tao Jiang. Frontiers in Human Neuroscience.