The short answer: not in the way the headlines claim. Cheese does contain a compound with a real, if much smaller, basis in science, but "cheese is basically crack" is a myth built on top of it.

Where the claim comes from

Cheese contains casein, the main protein in dairy. When you digest it, casein can break down into fragments called casomorphins. The name is a fusion of "casein" and "morphine," because these fragments have been shown in laboratory studies to bind to the same opioid receptors in your brain that opioids do. Because opioid receptors influence the brain's reward system, researchers have proposed that casomorphins could contribute to pleasurable responses to cheese.

Cheese also contains much more casein than milk by weight, because milk proteins are concentrated during cheese production. That is the entire basis for the "cheese is addictive" story.

So far, so alarming. But this is where the headlines stop and the actual science keeps going.

What the headlines leave out

Three things get dropped every time this claim goes viral.

First, casomorphins are dramatically weaker than actual opioid drugs, with far lower potency than morphine. Binding to a receptor in a lab is not the same as the effect of a drug. As one neuroscientist put it, just because something activates your opioid system does not make it addictive, and putting cheese on par with cocaine is more inflammatory than accurate. There is also little direct evidence that casomorphins from eating cheese produce meaningful dopamine effects in the human brain, which is the part the viral version tends to assume.

Second, it is genuinely unclear whether casomorphins reach your brain in meaningful amounts at all. For them to matter, they would need to survive digestion, cross the intestinal barrier, and then cross the blood-brain barrier, and human evidence that this happens in significant amounts is limited. A 2009 review by the European Food Safety Authority concluded that the available studies were not of sufficient quality to establish a cause-and-effect relationship between these peptides and health outcomes in humans.

Third, the famous study that started the panic did not actually crown cheese. The 2015 study by Schulte, Avena and Gearhardt, which used the Yale Food Addiction Scale, ranked foods linked to addictive-like eating, and the top of the list went to highly processed items like pizza and chocolate, not plain cheese, which landed far down the ranking. The researchers pointed to processed foods high in fat and refined carbs, the ones that deliver a concentrated dose absorbed quickly, as the real drivers. Cheese is often a passenger in those foods, not the engine.

What is actually going on when you crave it

The honest version is less dramatic but more useful. Cheese is rich in fat and salt, characteristics that make foods highly palatable and rewarding for many people, likely for evolutionary reasons tied to seeking out calorie-dense food. That makes it easy to overeat, the same way most rich, tasty foods are easy to overeat.

That is not addiction in the clinical sense. It is palatability. The lead researcher on the food-addiction study has said plainly that it is not cheese specifically, but processed foods that spike blood sugar quickly, that drive addictive-like eating patterns. Some researchers do argue that certain people show addiction-like responses to highly processed foods, and that debate is ongoing, but it is not a case against cheese on its own.

What this means in practice

Current evidence does not support the idea that cheese is addictive in the way drugs of abuse are, even though many people find it highly palatable and easy to overeat. If you love cheese, there is no reason to treat it like a substance to quit. It comes with protein, calcium, and fats, and enjoying it is not a disorder.

The thing worth watching is not some hidden opiate, it is the simple fact that cheese is calorie-dense and easy to eat a lot of, especially inside processed foods like pizza where it rarely travels alone. So enjoy it, and pay attention to how much and in what company, not because your brain is being hijacked, but because that is just how eating well works. The science can shift as more research comes in. But right now, the picture is clear: the casomorphin hypothesis is real, the evidence that cheese acts like an addictive drug is not.

Sources

Schulte EM, Avena NM, Gearhardt AN (2015). Which Foods May Be Addictive? The Roles of Processing, Fat Content, and Glycemic Load. PLOS ONE, 10(2): e0117959. PMID: 25692302. doi.org/10.1371/journal.pone.0117959

European Food Safety Authority (2009). Review of the potential health impact of β-casomorphins and related peptides. EFSA Scientific Report, 231: 1–107. doi.org/10.2903/j.efsa.2009.231r

This piece was written with the help of AI tools with human oversight. It is general information, not medical or nutritional advice.