What makes potato chips, french fries addictive?
The fats present in these foods trigger the body to produce natural marijuana-like chemicals, called endocannabinoids, which drive our gluttonous behaviour, researchers at the University of California, Irvine, found.
“This is the first demonstration that endocannabinoid signaling in the gut plays an important role in regulating fat intake,” study researcher Daniele Piomelli, a professor of pharmacology at the University of California, Irvine, said in a press statement.
Previously, a 2009 PNAS study found that people who smoke cannabis develop a craving for snacks (popularly called as munchies) because endocannabinoids in hypothalamus activate cannabinoid receptors which increase food intake.
Study details and findings
In order to test the effect of different kinds of food on brain, Piomelli and his colleagues fed laboratory rats with a sugar solution, a protein-rich liquid called peptone, or a high-fat beverage made of corn oil.
They then anesthetized and dissected the rats, rapidly freezing their organs for analysis.
Researchers discovered that when rats tasted fatty foods, cells in their upper gut started releasing endocannabinoids. Interestingly, sugars and proteins did not have this effect.
Endocannabinoids: the apparent culprit?
Starting from the tongue, fatty foods generate a signal that travels first to the brain, which in turn relays message down to the intestine via a nerve bundle called the vagus. Here, the message stimulates production of endocannabinoids, which further prompts craving for more intake of junk food.
Shortly put, fatty foods release digestive chemicals linked to hunger and satiety that compel us to eat more, the researchers said.
Dr Piomelli, director of the university's centre for drug discovery and development, added, “From an evolutionary standpoint, there's a compelling need for animals to consume fats, which are scarce in nature but crucial for proper cell functioning.
“In contemporary human society, however, fats are readily available, and the innate drive to eat fatty foods leads to obesity, diabetes and cancer.”
The Bright Side
However, scientists suggest that by blocking endocannabinoid receptors, they might be able to break the cycle that drives people to munch on fatty foods.
“Blocking endocannabinoid receptors in the brain can cause anxiety and depression,” Piomelli said, “but a drug designed to target the gut might not trigger those negative side effects.”