by Anne Kessler
True to my roots, I am a cheese enthusiast. Born and raised in Wisconsin, the leader in US cheese production (sorry not sorry California), I grew up thinking that eating cheese and only cheese in a room full of people donning green and gold jerseys and bright yellow ‘cheeseheads’ was just another Packer Sunday. True to what our license plates say – America’s Dairyland – Wisconsin produces over 25% of all our nation’s cheese each year. Quantitatively speaking, this means that in one state alone in a single calendar year, over one million cows from more than 10,000 dairy farms produce nearly three billion pounds of cheese.
Despite declining milk consumption in America (all varieties, including cream and ice cream products), dairy utilization has continued to rise nationwide – largely due to a steady increase in cheese consumption over the last 40 years. Currently, US cheese consumption is roughly 34 lbs per capita with data trends predicting a rise to nearly 40 lbs per capita by the early 2020s. Just last year, researchers from the University of Michigan published a cross-sectional study that provides some insight into why – other than the obvious ‘it’s delicious’ – the average American consumes such a large quantity of cheese per annum: Cheese may be an ‘addictive’ food.
Schulte et al. conducted a two-tier study, investigating foods and food attributes that are associated with ‘addictive-like eating behaviors.’ In the first study, collegiate undergraduate students completed the Yale Food Addiction Scale (YFAS), a self-report tool that assesses addictive-like eating behaviors on the basis of criteria that is used to clinically assess substance dependence. Subsequently, the students were given a forced-choice task where they indicated in head-to-head comparisons, which foods (35 foods in total; each compared to one another) were more associated with addictive-like eating behaviors. The second study, which used the same 35 foods and a more diverse study sample, focused on individual differences that may be responsible for addictive-like eating behaviors. All tier-two participants completed the YFAS and then rated their own likeliness to experience addictive-like consumption problems for each food.
For both tiers, study findings indicate that highly processed foods (pre-defined as foods with added amounts of fat and/or refined carbohydrates), and simply a high fat content in general, appear to be associated with addictive-like eating behaviors. Schulte, the study’s primary author, summarized the findings in a post-publication interview, stating that “fat (a major component of cheese), appears to be equally predictive of problematic eating for everyone, regardless of an individual’s basal level of addictive-eating behaviors.” As anticipated, those of the 35 foods included in the study containing cheese (i.e. pizza, cheeseburger), as well as cheese alone, were ultimately listed as highly problematic for both of the study populations.
Following the publication of Schulte’s study, a parade of articles referring to cheese as “dairy crack” and suggesting that it is “just as addictive as hard drugs” began to surface in the press and subsequently on every social media platform. Shortly thereafter, I received an e-mail from a fellow cheese-loving, college friend with a link to a reactionary article in the LA Times. In their explanation of what they coined “the science behind cheese addiction,” the article discussed the small, active chains of amino acids that are produced when the human body breaks down the milk-derived protein casein. Casein is highly concentrated in cheese, so it is likely that high levels of its partial breakdown products, known as casomorphins, would be abundant in the human body following cheese consumption. Because casomorphins are known to bind human opioid receptors in a similar manner as drugs like heroin and morphine, cheese probably elicits feelings of serenity and euphoria and is therefore just like crack.
Except for the fact that upon actual research…it isn’t.
Casomorphins have been extensively studied in both cellular (in vitro) and model systems; however, their biologic activity and utilization in human health and disease remains to be established. With regards to the story presented here, there is no data (obtained from human or mechanistic studies) to support the biologic activity and human host response mechanism that was loosely described in all of the articles that flooded the web after the publication of the food addiction study. In fact, a review article summarizing milk-derived opioid proteins indicates that despite high concentrations of casein in milk-derived products, the actual level of casomorphins measured in adult subjects post-consumption is negligible relative to the physiologically relevant level required for substantial binding of human opioid (in this case, μ) receptors. Additionally, the speed at which casomorphins are ultimately broken down by enzymatic degradation (human digestion) would further reduce their already not-so-potent effects, particularly in a body system outside the gastrointestinal tract (such as the central nervous system).
Thus, it remains both possible and plausible that given what we know about cheese (dairy processing, nutritional attributes, metabolism, etc.), it may be just as addictive as crack. But until we know more, I think that I will stick to what my mother fed me and continue eating it.
- 2015 Dairy Data (1-12), Wisconsin Milk Marketing Board
- Schulte, EM et al. PLoS ONE 10(2): e0117959 (2015).
- Harris, Jenn. “Is cheese really like crack?” Los Angeles Times 23 October 2015.
- Teschemacher, H et al. Biopolymers 43(2): 99-117 (1998).
- Countless PubMed searches: 0 results.
Annie got her start in science at the University of Wisconsin-Madison where she earned a BS in medical microbiology and immunology. Currently, she is a PhD candidate at Albert Einstein College of Medicine, studying pediatric cerebral malaria with a focus on host immunology and outcomes in HIV and malaria co-infection. In collaboration with the Blantyre Malaria Project, Annie travels to Malawi during the ‘rainy season’ to collect and process the patient samples required for her thesis work. Outside of the lab, she enjoys running, searching for NYC’s best cup of coffee, and rooting for the Wisconsin Badgers.