You may have seen a few headlines last week proclaiming that research shows we’re addicted to cheese, or that cheese really is crack.
While it’s all in good fun (maybe?) to exaggerate your love of foods by claiming they’re addictions, it's important to remember that scientifically, practically, and even metaphorically speaking, eating cheese is not even a little bit like smoking crack cocaine.
The truth is that the two sources of scientific information that were most-cited in these stories actually don’t show cheese has addictive properties.
The first one, a study published this year by researchers at the University of Michigan, asked two different groups of people to rank a list of 35 foods from most to least addictive. Tasty items like pizza, chocolate and chips shot to the top of the list. Based on these responses, the UMich researchers hypothesized that highly processed foods with added fats and refined sugars are most likely to feel “addictive” to people. All the researchers did was perform a statistical analysis of the different types of listed food and speculate as to why they might be more addictive than others. That's it.
The researchers themselves were uncomfortable with the "cheese is crack" headlines, and point out that their study found the opposite: people mostly struggle to control their intake of highly processed foods, not necessarily cheese.
"Our study found that people reported cheese ... as less problematic than highly processed foods that contained added fat and high [glycemic load],” lead researcher Erica Orenstein told HuffPost. "Thus, the bounds of our data suggest that highly processed foods are most implicated in addictive-like eating."
The second source of scientific data cited by most of the “cheese is crack” stories is a 2011 book called 21-Day Weight Loss Kickstart: Boost Metabolism, Lower Cholesterol, and Dramatically Improve Your Health by Dr. Neal Barnard. In it, he cites a bunch of studies that date from 1981 to 2000 about how dairy products have a protein called casein, and that when your body starts to metabolize the protein during the digestive process, the protein breaks into peptides called casomorphins that, chemically speaking, look similar to opioid drugs (think morphine and heroin). Opioids work by binding to a protein called an opioid receptor that's found in the brain, spinal chord and GI tract. This dulls the body’s perception of pain, which is why so many opioid-based drugs are prescribed after surgery.
Barnard calls cheese “dairy crack,” which is probably the origin of many of these headlines. Barnard was not available to respond to requests for comment, but his colleague Cameron Wells, a dietitian and clinical researcher at Barnard's Physicians Committee for Responsible Medicine, a nutrition research and animal rights advocacy non-profit, admitted to HuffPost that the “crack” description is sensationalized and just a way to draw readers in.
But Wells also points out that the casomorphins in cheese do resemble morphine molecules, and that the point of all this is to figure out why so many people keep eating large amounts of saturated fat despite evidence that it contributes to heart disease.
“As a country we do consume a lot of dairy, and cheese specifically, and our health as a whole is not great,” said Wells. "It could really be a valuable tool if we’re able to understand why."
However, more recent evidence suggests the casomorphin effect is so mild as to be negligible. A 2009 study review on casomorphins, conducted by the European Food Safety Authority, found that researchers could only elicit opioid-like effects in animals if they injected the stuff straight into their body cavity or brain -- i.e., not via digestion of dairy products.
The report also found that casomorphins are highly vulnerable to a chemical process called hydrolysis, which is when water breaks the bonds of a molecule. That’s why they don’t really pass intact through the intestines and into the blood-brain barrier, which means they couldn’t access those opioid receptors in the brain even if they wanted to. In principle, it’s possible, the EFSA researchers write, but there’s no data to show that the opioid-like peptide has passed through the intestines intact except in the cases of newborns or people with specific diseases, whose intestines are more permeable than those of a healthy adult.
In comparison to pharmaceutical opioids or the opioids we produce naturally (such as endorphins, those responsible for the “runner’s high”), casomorphin "does not seem to be a very potent opioid ligand,” concludes the EFSA report.
The comparison to crack is also particularly inapt since crack cocaine isn't even an opioid. But now for the final nail in the coffin: the medical definition of addiction. It’s a chronic brain disease in which your need for a substance is so strong that you often can’t stop using it, even if you want to stop. An addicted brain builds tolerance to the substance, which means you need to keep upping your dose to feel the same high. Not having that substance elicits withdrawal symptoms that hurt, physically and mentally. Finally, addiction’s effects are so strong that the craving distorts your relationships, personal values and your connection with yourself.
So, yeah. Cheese isn’t like crack, because you didn’t cut out all of your friends and sell your stuff to get just a little bit more of that Roquefort. But you already knew that, right?
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