Coffee is one of the most popular beverages worldwide, consumed daily by millions for its stimulating effects. Recent research published in the journal Neuropsychopharmacology sheds light on how our genetic makeup is associated with our coffee consumption habits. The findings provide evidence that coffee consumption is a heritable trait.
The research team was intrigued by coffee’s potential as a substance that could develop into a dependency, similar to other psychostimulants. Caffeine, the primary psychoactive component in coffee, can lead to tolerance, withdrawal, and dependence, much like other substances. Given coffee’s widespread use and its potential impacts on health—both positive and negative—the researchers sought to understand the genetic underpinnings of coffee consumption.
The study utilized data from two large cohorts: US-based participants from 23andMe, Inc. (130,153 participants) and the UK Biobank (334,659 participants). Both cohorts included individuals of European ancestry who provided information on their daily coffee consumption. The 23andMe participants answered the question, “How many 5-ounce (cup-sized) servings of caffeinated coffee do you consume each day?” In contrast, the UK Biobank participants answered, “How many cups of coffee do you drink each day? (Include decaffeinated coffee).”
Genetic data were collected from saliva samples and processed to identify single nucleotide polymorphisms (SNPs), which are variations in the DNA sequence that can affect various traits. The researchers conducted genome-wide association studies to pinpoint specific genetic variants associated with coffee consumption.
In a GWAS, researchers scan the entire genome of many individuals, looking for SNPs that occur more frequently in those with a particular trait or condition compared to those without it. By comparing the genetic differences between these groups, GWAS can pinpoint specific regions of the genome that may contribute to the trait or disease being studied.
One of the primary findings of the study is that coffee consumption is a heritable trait, meaning that genetic factors significantly contribute to how much coffee individuals consume. The researchers identified seven genetic loci associated with coffee intake in the 23andMe cohort. Most of these loci are involved in metabolic processes, with notable genes including CYP1A1 and CYP1A2. These genetic variants influence how quickly individuals metabolize caffeine.
“As we expected, the decision to consume coffee is partially influenced by individual genetic differences. Moreover, we were able to confidently identify specific genes that influenced coffee consumption, including some that influence how quickly caffeine is metabolized,” said Hayley H. A. Thorpe, the lead author on the paper and a postdoctoral fellow at Western University.
The researchers calso found positive genetic correlations between coffee consumption and various substance use traits. For instance, individuals with a genetic predisposition for higher coffee intake were also more likely to have genetic correlations with smoking initiation, alcohol consumption, and cannabis use. This suggests a shared genetic basis for coffee consumption and other substance use behaviors.
“Drinking coffee excessively can be problematic; by identifying genetic variants associated with excessive coffee consumption we hope to learn something fundamental about why people may overconsume other substances,” said co-author Sandra Sanchez-Roige, an associate professor in the University of California San Diego School of Medicine Department of Psychiatry
Additionally, the study revealed positive genetic correlations between coffee intake and obesity-related traits, such as body mass index (BMI). But “this only tells us that the genetics of coffee intake are associated with obesity odds. While it could be the case that people with this genetic liability end up drinking more coffee and the coffee intake in some way increases obesity risk, there could also be indirect mechanisms at play,” Thorpe explained.
“For example, your genetics may make you more likely to consume coffee, but how do you take that coffee you drink every day? Do you like it black, or do you exclusively drink sugar- and dairy-heavy coffee-based drinks? Our study didn’t assess how people prefer to drink their coffee, but consistently drinking these additives along with coffee could affect a person’s health as well.”
Interestingly, the study highlighted significant discrepancies between the two cohorts regarding genetic correlations with other traits. For example, in the 23andMe cohort, coffee consumption was positively correlated with anxiety-related traits, while in the UK Biobank cohort, these correlations were negative.
Similarly, cognitive traits such as executive function and intelligence showed positive genetic correlations with coffee intake in the UK Biobank cohort but negative correlations in the 23andMe cohort. These inconsistencies suggest that cultural, geographic, or other environmental factors may influence the genetic associations observed in different populations.
“Our most surprising result was the differences between the genetic influences on coffee consumption in the US versus the UK,” Thorpe said. “Our study design allowed us to examine other behaviors, physical characteristics, and diseases that were associated with the genetics of coffee consumption. There were similarities in both populations, including positive correlations between the genetics of coffee intake with the use of other drugs and obesity. However, many other traits, such as psychiatric disorders like anxiety, showed opposing relationships with coffee consumption genetics between the US and the UK populations.”
While the genetic correlations observed in this study were mostly with adverse outcomes, particularly substance use disorders and obesity-related traits, that shouldn’t be misinterpreted as suggesting that coffee itself is causing these outcomes.
“We don’t want anyone’s takeaway from this study to be that drinking coffee leads to better or worse health,” Thorpe explained. “Our study is specifically focused on the genetics of coffee intake, and what relationships these genetics have with health. Our study supported that the genetics of coffee intake may be simultaneously associated with health benefits and adversities, depending on what health trait is being looked at.”
“Our study also tells us that the health outcomes of coffee intake genetics could vary widely across different populations and contexts. How someone drinks coffee and the habits surrounding its intake are likely key to its health outcomes. Whether coffee intake is ‘good’ or ‘bad’ for someone is likely very dependent on the individual, the context, and health domain in question.”
The study provides valuable insights into the genetic basis of coffee consumption, highlighting the significant role of genetic factors in influencing our coffee drinking habits. But there are some limitations to consider. The study focused primarily on individuals of European ancestry, limiting the generalizability of the findings to other populations.
The researchers also noted that different methods of measuring coffee consumption across cohorts could contribute to the observed discrepancies. For example, the 23andMe cohort specifically measured caffeinated coffee intake, while the UK Biobank included both caffeinated and decaffeinated coffee.
Future research should aim to replicate these findings in more diverse populations and explore the potential interactions between genetic and environmental factors in coffee consumption.
“Genes are not destiny and we identified a huge contribution of the environment; we can all relate drinking more coffee than necessary upon a sleepless night, or not drink coffee at all when feeling poorly,” Sanchez-Roige said. “Genes and environment work in synchrony, and our study uncovered that the genetics of coffee consumption measured in participants from the US were not equal to those from the UK. Differences in coffee types (added sugar, types of brew), patterns of drinking (alone, during a social gathering) as well as other behaviors (obtaining consumption from other sources, such as tea) may explain some of these differences. Identifying which associations are driven by genetics versus the environment, or both in concert, is a key next step for this line of work.”
The study, “Genome-wide association studies of coffee intake in UK/US participants of European ancestry uncover cohort-specific genetic associations,” was authored by Hayley H. A. Thorpe, Pierre Fontanillas, Benjamin K. Pham, John J. Meredith, Mariela V. Jennings, Natasia S. Courchesne-Krak, Laura Vilar-Ribó, Sevim B. Bianchi, Julian Mutz, the 23andMe Research Team, Sarah L. Elson, Jibran Y. Khokhar, Abdel Abdellaoui, Lea K. Davis, Abraham A. Palmer, and Sandra Sanchez-Roige.
