If you love cheese, you might as well be doing crack.
Or at least that’s what you might gather from recent health news vilifying one of America’s favorite fatty foods. “Science declares what we all know: Pizza is the most addictive food,” MTV news reported last October. The LA Times claimed that, “Cheese really is crack.” And GQ recently said, “Science says cheese is basically cocaine.” Journalists backed these claims by citing research conducted at the University of Michigan by Ashley Gerhardt and colleagues allegedly showing that cheese addiction is real. But the study itself said no such thing.
Gerhardt’s paper examined the fat and sugar properties of 35 foods and their potential for addictive-like eating behaviors. In the experiment, participants ranked 35 foods on a scale from 1 (easy to resist) to 7 (difficult to resist). Pizza won first place, with an average score of 4.01. Cheese got tenth place, with a score of 3.22, making it slightly less appealing than pizza. In another experiment, participants who were shown pairs of foods indicated which was harder to avoid. After comparing all possible combinations of the 35 foods, chocolate came in first place, while cheese trailed at sixteenth.
Ranking cheese-laden pizza as more difficult to resist than chocolate (clearly debatable) and cucumbers (obviously) does not prove that it is the most addictive food, or that it is addictive at all.
Food addiction is a contentious concept with an unclear biological mechanism. Addiction itself has many debated definitions, but usually refers to a change in the “reward-seeking” regions of the brain involving the “feel-good” chemical dopamine. Despite what the news reports implied, Gerhardt’s study made no claims regarding cheese addiction, or regarding cheese at all. She actually concluded that highly processed foods—those containing artificially high levels of sugar and fats—are potential candidates for food addiction. Cheese is indeed fatty, but was not considered highly processed by Gerhardt’s definition.
So where did all this “cheese is crack” business come from?
Dr. Neal Barnard from the Physicians Committee for Responsible Medicine (PCRM) is often quoted calling cheese “dairy crack.” The PCRM is a vegan-diet-promoting organization previously funded by PETA. The PCRM’s article “Three Steps to Fight the Cheese Addiction” provides little scientific explanation of “cheese addiction” and instead markets vegan products and dairy-free cookbooks.
Barnard rightly mentions that casein – the principle protein component of cheese – breaks apart into fragments called casomorphins due to digestive enzymes in the stomach. But his facts get shaky when he says that casomorphins activate brain opioid receptors like heroin and morphine do.
Heroin and morphine addiction results from the drugs’ effects on opioid receptors found in the brain and, to some extent, in the gut. But unlike brain-based opioid receptors, those in the gut react far less powerfully and do not result in addiction. For cheese to be addictive, the gut would need to absorb casomorphins into the bloodstream and pass them across the blood-brain barrier, and no study to date shows that casomorphins can do that.
Cameron Wells, PCRM’s Associate Director of Clinical Dietetics told me that looking at cheese from a biochemical perspective distracts from the nutritional component. Americans consume about three times as much cheese now as they did in the 1970s, and the high levels of saturated fats and cholesterol aren’t helping anybody’s heart health. Suggesting that people cut down on fatty foods like cheese, as well as processed and red meats, is solid guidance amidst a flurry of seemingly changing health advice.
When pressed for an answer to the literalness of the “cheese addiction” epidemic, Wells did stand by PCRM’s claim that cheese is chemically addictive due to casomorphins. But she was unaware of the European Food Safety Authority’s study concluding no evidence for risk of addiction or any other disease from ingestion of casomorphins.
Those opioid receptors in the gut are not involved in cheese addiction, but they do have an important function. When activated they slow peristalsis and gastrointestinal transit time. In other words: constipation. So today when you load your burrito bowl with heaping scoops of queso, shredded cheese, and sour cream, eat merrily, free from fear of addiction. But tomorrow, when you’re upset from over-activation of your gut opioid receptors, well… you’ve been warned.