Recent news headlines suggest people who eat cheese all of the time may be addicted.
Every year, people in America eat more than thirty-five pounds of cheese per person. Along with plenty of cheddar cheese in people's refrigerators, we are eating cheese melted on many foods such as quesadillas, omelets, pizza, sandwiches, on pasta and vegetables and more. Even though cheese is delicious, taste might not be the only reason people are eating so much cheese. As it turns out, cheese may also be addictive.
Casomorphins are defined as any of several peptides, (protein fragments), formed during the metabolism of casein, that have opiate activity.
Cheese is a delicious food, yet if you saw the news recently you might think it is on its way to being classified as a Schedule II drug. Headlines suggested that people who eat cheese all of the time may be addicted. Another news site compared cheese to crack cocaine. The stories referred to a study looking at the addictive properties of different foods; pizza was at the top of the list. Why? The addictive properties of cheese, which some articles claim contains dangerous opiate-like chemicals called, 'casomorphins.'
Yet people cannot explain away their affinity for cheese by saying they are addicted. The study in news stories was published in PLOS ONE and did investigate which foods are most associated with addictive-like eating behaviors. Pizza did come out on the top in one experiment. The scientists who performed the research say this has little to do with the dairy products involved. Instead, the scientists argue the foods we crave most are ones processed with high levels of fat and sugars and it is these ingredients that leave people wanting more.
Ashley Gearhardt of the University of Michigan in Ann Arbor who led the study stated, 'I was horrified by the misstatements and the oversimplifications... and the statements about how it's an excuse to overeat.' She continued by saying, 'Liking is not the same as addiction. We like lots of things. I like hip-hop music and sunshine and my wiener dog, but I'm not addicted to her. I eat cheese every day. That does not mean you're addicted or it has addictive potential.'
Ashley and her colleagues set out to determine which foods are most closely associated with addictive-like eating behaviors. They recruited 120 undergraduates and another 384 people from Amazon’s Mechanical Turk to take the Yale Food Addiction Scale. The survey is designed to identify signs of addictive behavior toward food and is based on similar criteria for drug addiction. The questionnaire asks people to rank how often they eat more than intended or overeat, if they have persistently attempted to quit overeating certain foods and failed to succeed and whether they have given up or reduced important recreational and social activities to pursue their food of choice.
In the first experiment, scientists gave the people involved in the study choices between two different foods and asked them to select which of the items they were most likely to crave or binge eat repeatedly. Selections included:
For each option the participants had to make a choice - Cheeseburgers or water? Apples or cookies? In the second experiment, the Mechanical Turk participants were not asked to make a choice. Instead, they were asked to rate the same foods on a seven-point scale based upon how likely they were to crave or binge on the foods, with one as not problematic and seven as extremely problematic.
The most highly ranked foods were the ones that were highly processed such as cake, chips and pizza. Foods low in carbohydrates such as eggs or nuts, or foods low in fat such as strawberries and bananas, ranked low. Ashley said, 'When it comes to naturally occurring foods, even ones that people really like - apples, nuts, strawberries - people like them but they don't lose control, they don't have cravings. In contrast, when you look at highly processed foods, chocolate and pizza, those are the foods people struggle with.'
Ashley stated that pizza and chocolate and other highly processed foods are high in salt, fat and carbohydrates. They have a high glycemic load, getting absorbed more quickly by a person's body than granola bars, nuts, or eggs. Quick absorption means a fast spike in blood sugar which has the potential to make these processed foods more likely to produce addictive-like behaviors. Ashley said, 'What we think is important is that high glycemic load foods, foods that give intense rapid blood sugar spikes, were the most problematic.'
When the researchers measured how frequently a food was problematic for participants, cheese was not even in the top ten. Instead, it came in at sixteen out of thirty-five, below:
When the second group was asked to rank foods on a scale of one to seven, cheese did a bit better at number ten. It was still outclassed by chocolate, pizza, french fries, chips and more. When it comes to sugars and other carbohydrates, cheese is a failure. Ashley stated, 'Cheese doesn't have a high glycemic load at all.' When it comes to pizza, the cheese is not the issue. Instead, it is the high carbohydrate levels in the sauce and crust. Cheese on its own is not especially problematic.
Yet cheese and cocaine do have something in common other than both starting with the letter, 'c.' Cheese, like other foods, stimulates the reward system in a person's brain. Joseph Frascella, a neurologist at the National Institute on Drug Abuse in Bethesda, Md. Stated, 'We know there are these areas of the brain, reward circuits involved in keeping us alive. They are systems that signal to us when something we do is good, like eating, procreating or drinking water when you're thirsty.' These systems are necessary to let us know what our bodies need and to teach us to seek it out.
These are the same systems in the brain that addictive drugs exploit. Joseph said, 'Drugs of abuse hit these same pathways and they tend to do it much more effectively. So when you get that rush, that high, and the brain says wow that's good for us, do it again.'
Even though cheese might be able to give a person good feelings, when it comes to addictive properties, cheese cannot be compared. Peter Kalivas, a neuroscientist at the Medical University of South Carolina in Charleston said, 'Addictive drugs do things that food doesn't do that make them more addictive. To put those foods on par with something like cocaine is pretty inflammatory.'
News coverage of the topic comparing cheese to crack cocaine concentrated on the role of casomorphins, which are small protein fragments that result from the breakdown of the milk protein casein. The fragments can bind to receptors for opioid molecules in a person's brain.
Ashley warns, 'Just because something activates your opioid system doesn't make it addictive.' A scientific report on casomorphins from the European Food Safety Authority in 2009 stated that it is unknown whether these molecules escape from the gastrointestinal track in large amounts, or that they can get into the brain, although it is possible. When injected directly into animals, either into the body cavity or the brain, casomorphins did produce some effects such as pain relief or learning delays in newborn mice.
Yet the peptide was also estimated to be twenty times less potent than morphine. In a dairy-funded study from 1994, rats were given casomorphin or morphine and placed in different chambers, allowing them to associate the drug with a particular chamber. After a number of days, researchers looked at which chamber the rats preferred spending time in, a common test of the rewarding properties of drugs such as morphine. While the rats were happy to spend time in a chamber associated with morphine as compared to water, casomorphin produced no response.