More than 40 million dairy cows are farmed annually for their milk in North America and Europe alone. Not only do cows produce methane, which is a significant greenhouse gas emission contributing to climate change, they suffer mentally and physically from an industry that tends to view them as “milk machines” rather than as sentient beings. Dairy production is also rife with pathogens, including listeria, e-coli, salmonella, and more recently, avian flu, which can remain in milk even after pasteurization.

Despite these harms, consumption of cow’s milk and other dairy products remains widespread. Global dairy production increased 30% between 2005 and 2015, and the industry overall is expected to grow roughly 1% each year between 2021 and 2031.

Scientists seeking to better understand the disconnect between the negative impacts of dairy products and their consumption conducted two studies — one online and the other in person — to see whether disgust could deter people from drinking milk and eating milk chocolate. Their results show that although people report a willingness to reduce consumption, they don’t necessarily follow through.

Feelings of disgust over food, while uncomfortable, are important for human survival. They prevent our species from eating spoiled, diseased, or toxic food that could make us sick. Previous studies found that eliciting disgust in people around meat reduced their opinion of meat and their intention to eat it. But until now, researchers had not examined whether disgust could influence milk consumption.

Making The Milk-Lactation Connection

In this study, scientists from the University of Edinburgh conducted two experiments in which they emphasized the origin of milk as a bodily fluid susceptible to contamination from pathogens. The first experiment, conducted online with a sample size of 155 people, had five parts:

1. Participants were asked about their willingness to alter their dairy consumption.
2. They then read an information sheet that contained neutral information about cows.
3. Next, they rated how “grossed out,” “disgusted,” and “queasy, sick to my stomach” they felt about consuming cow’s milk.
4. Participants were then randomly assigned to read information about either cow digestion or cow lactation and the pathogens associated with these processes. Afterward, they were asked to fill out a questionnaire about how they felt about drinking cow’s milk and eating dairy products and other foods.
5. Lastly, the questionnaire asked for details about age, gender, level of education, and other demographics.

The researchers found that emphasizing the connection between cow’s milk and lactation and pathogen susceptibility increased feelings of disgust and reduced a person’s willingness to drink it.

Intentions Versus Behavior

The second experiment, which had a sample size of 76 participants, was conducted in person to test whether the results from the first experiment would induce people to change their eating behavior. After participants were asked to read neutral information about cows and then rate how they felt about consuming cow’s milk, they were prompted to go into a different room and prepare a bowl of milk chocolates to be eaten as a snack later while watching a 15-minute movie about caves. The activity was labeled as an attention break, but it was a ruse to mask the experiment’s purpose.

After the participants left the snack room, their bowls were purposely removed. Meanwhile, back in the original room, they read an information sheet about cow lactation and the pathogens associated with it and then filled out a questionnaire about how they felt about drinking cow’s milk. When they returned to the snack room, they were told that their bowls had accidentally been given to another participant and they’d have to prepare new ones. They did, and while they were being debriefed, an experimenter weighed and recorded both servings.

The researchers found that although emphasizing the connection between cow’s milk and lactation and pathogen susceptibility increased feelings of disgust in participants (as in the first experiment), it didn’t compel them to reduce the size of their milk chocolate servings.

That participants felt disgusted by cow’s milk but didn’t reduce their milk chocolate servings could be the result of limitations within the study. The research team postulates, for instance, that milk chocolate candies might not be as closely associated with cow lactation as milk, yogurt, or cheese. They suggest repeating the experiment using more typical dairy products like these.

For farmed animal advocates, though, reminding consumers of the connection between cow’s milk and lactation and pathogens — especially those that result from fecal matter — shows promise. However, further studies are needed to pinpoint effectiveness and what may ultimately influence behavior in an industry where food products are so widely disassociated from their animal origins.