Drinking coffee runs in families and is influenced by genetics. Sandra Sanchez-Roige, a psychiatrist at University of California San Diego, collaborated with researchers worldwide to study coffee habits using data from 23andMe and the U.K. Their study, led by Hayley H. A. Thorpe from Western University, Ontario, used genetic data and surveys to conduct a large-scale study. They aimed to link specific genes associated with coffee drinking to health traits and conditions.
Researchers analyzed this data to find parts of the genetic code linked to whether someone drinks more or less coffee. Then, they looked into the genes and biological processes that might explain why people drink coffee.
Many people are surprised to learn that genetics can affect coffee consumption. Previous research suggested that some genes impact how much coffee a person drinks. So, it wasn’t surprising when this study confirmed that genetics plays a role in both groups they studied. Simply put, the genes you inherit from your parents influence how much coffee you’ll likely drink.
Sanchez-Roige explained that their research focused on two main questions about coffee.
“The first question was about how much genetics affects coffee drinking,” The second question, which coffee lovers are interested in, is whether coffee is good or bad for health. Does it have positive effects or negative?”
The answer isn’t clear-cut. Their study compared genetic data from over 130,000 people in the U.S. and over 330,000 in the U.K. They found consistent genetic links between coffee consumption and adverse health outcomes like obesity and substance use.
A positive genetic association means a specific gene variant is linked to a condition. In contrast, a negative association might protect against it. However, the findings become more complex when looking at psychiatric conditions.
Thorpe explained, “For example, when we looked at anxiety, bipolar disorder, and depression in the 23andMe data, we found they were often genetically linked with coffee consumption. However, in the U.K. Biobank data, we saw the opposite pattern: these conditions were genetically less associated with coffee intake. This was unexpected.”
Thorpe noted other discrepancies between the 23andMe and U.K. Biobank datasets, especially concerning psychiatric conditions.
Thorpe said, “In research, combining similar datasets is common to increase study power. However, combining these two datasets wasn’t a good idea.” She explained that merging the databases could obscure effects, leading to incorrect conclusions or nullifying each other’s findings.
Sanchez-Roige explains that the differences in results have several explanations. Firstly, there needed to be greater consistency in how the surveys were conducted. For example, 23andMe asked about servings of caffeinated coffee per day in specific measurements. In contrast, the U.K. Biobank asked about cups of coffee per day, including decaffeinated.
The surveys didn’t account for different coffee preferences, aside from serving size and caffeine content. Thorpe noted that instant coffee is more prevalent in the U.K., while ground coffee is preferred in the U.S.
And then there’s the influence of drinks like frappuccinos, which refer to the American practice of adding sugary ingredients to coffee. Palmer mentioned other caffeinated beverages and the inclusion of tea in the U.K. Biobank, which weren’t part of the GWAS and were focused only on coffee.
Palmer emphasized that the study highlights how genetic factors influencing coffee consumption differ significantly from those influencing tea consumption.
Genetics influences many traits, like height. These traits generally play out similarly whether in the U.S. or the U.K. But coffee consumption is a personal choice.
Sanchez-Roige noted that coffee comes in various forms and is consumed differently based on cultural norms. Someone with the same genetic makeup might drink coffee differently in the U.K. compared to the U.S.
Sanchez-Roige said, “That’s what the data are showing us. Unlike height, where behavior is minimal, coffee consumption is heavily influenced by personal choices and environmental factors. This interaction between genetics and environment makes the situation more complex.”
Journal reference:
- Thorpe, H.H.A., Fontanillas, P., Pham, B.K. et al. Genome-wide association studies of coffee intake in UK/US participants of European ancestry uncover cohort-specific genetic associations. Neuropsychopharmacology. DOI: 10.1038/s41386-024-01870-x.