According to a small new study, your nose can guide you to make more balanced eating decisions.
When 30 participants ate cinnamon or pizza loaves, the researchers found that they were less sensitive to these odors than when they were still hungry.
Anyone who has pinched their nose and eaten a food fork knows that their smell can influence the taste they have something, but this new research suggests that a taste can also influence our smell, moving away -to us towards some foods and moving away from others.
Researchers suspect that this is our brain’s way of making sure we don’t eat too much of it – a possible adaptive strategy to optimize our search for food.
“If you think of our ancestors roaming the forest trying to find food, they find and eat berries and are no longer as sensitive to the smell of berries,” explains neurologist Thorsten Kahnt of Northwestern University.
“But maybe they’re still sensitive to the smell of mushrooms, so it could theoretically help facilitate diversity in food and nutrient intake.”
Previous studies have found our subjective opinions about whether certain foods smell nice depends on what we eat, but this study tried to determine if hunger and satiety can change our sensitivity to smells.
So far only a few animal studies and one human study have explored this idea, which means there are many unanswered questions.
Research on rodents, for example, has found that fasting can influence the level of activity of the olfactory bulb, which processes the smell in the brain.
In addition, in 2019, two of the same authors of the new research found that lack of sleep in humans can exacerbate the odors of high-energy foods within the island’s crust, a part of the olfactory pathway that responds to related stimuli. with food.
These results were preliminary, but suggested that our appetite could influence our sensitivity to certain odors.
In the new study, researchers presented 30 hungry participants in the lab, after fasting for at least six hours. Inside an MRI scanner, these volunteers were presented with a series of 10 scents, which contained a mixture of two scents: one perfume was pizza or cinnamon buns and the other was a pine or cedar scent.
The ratio of food to non-food in the odor mixtures was different for each of the 10 samples, and participants determined which odor they thought was most dominant for each: pizza or pine, or cinnamon or cedar.
Volunteers were given pizza or cinnamon food before completing the task again from the MRI machine.
“Parallel to the first part of the experiment that was done with the MRI scan, I was preparing food in another room,” explains Northwestern neurologist and the study’s first author, Laura Shanahan. .
“We wanted everything to be fresh, ready and warm because we wanted the participant to eat as much as he could until it was very full.”
Participants were able to quickly identify odors more purely (when an odor was clearly dominant). But when the aroma mix became more uniform, what the participants had eaten in the lab seemed to have an impact on what they smelled.
Those who were given a pizza meal, for example, were less likely to smell the pizza when mixed with pine. Meanwhile, those with a cinnamon bun filling were less likely to smell baked goods when mixed with cedar.
However, when these same participants were hungry at the beginning of the day, they were much better at distinguishing the dominant odor.
For example, a hungry participant at the beginning of the day might have needed only half the smell to smell pizza to perceive it as dominant in the pine. But later, when that same participant had eaten pizza, they might have needed 80% of the smell to smell the pizza to perceive it as dominant.
In examining the results of MRI machines, the researchers observed a similar pattern occurring in the brain.
Explorations revealed that different olfactory pathways are activated after a meal than before a meal. For example, after eating with cinnamon buns, participants showed fewer “food-like” responses to the same sweet smell.
Unfortunately, MRI scans are limited because they are not able to measure neuronal activity directly in the olfactory bulb, so we do not yet know where these changes in our sense of smell are actually occurring.
“We’re tracking how this information is modified and how the rest of the brains use the modified information to make decisions about food intake,” Kahnt says.
The study was published in PLOS Biology.