Coffee is one of the most popular beverages in the world, consumed by millions of people every day for its stimulating effects. A recent study published in the journal Neuropsychopharmacology sheds delicate on how our genetic makeup is linked to our coffee consumption habits. The results provide evidence that coffee consumption is a heritable trait.
The research team was intrigued by coffee’s potential to develop into an addictive substance, similar to other psychostimulants. Caffeine, the main psychoactive ingredient in coffee, can lead to tolerance, withdrawal, and addiction, similar to other substances. Given coffee’s widespread apply and its potential health effects—both positive and negative—scientists sought to understand the genetic basis of coffee consumption.
The study used data from two vast cohorts: US participants from 23andMe, Inc. (130,153 participants) and the UK Biobank (334,659 participants). Both cohorts included people of European descent who reported their daily coffee consumption. 23andMe participants answered the question, “How many 5-ounce (cup-sized) servings of caffeinated coffee do you drink each day?” and UK Biobank participants answered, “How many cups of coffee do you drink each day? (Including decaffeinated coffee).”
Genetic data was collected from saliva samples and processed to identify single-nucleotide polymorphisms (SNPs), which are variants in DNA sequences that can affect a variety of traits. The researchers conducted genome-wide association studies to pinpoint specific genetic variants associated with coffee consumption.
In a GWAS study, scientists scan the entire genome of many people, looking for SNPs that are more common in people with a given trait or condition than in people without that trait or condition. By comparing the genetic differences between these groups, a GWAS study can pinpoint specific regions of the genome that may contribute to the trait or disease being studied.
One of the study’s key findings is that coffee consumption is a heritable trait, meaning that genetic factors significantly influence how much coffee individuals consume. The researchers identified seven genetic loci associated with coffee consumption in the 23andMe cohort. Most of these loci are involved in metabolic processes, with CYP1A1 and CYP1A2 among the more essential genes. These genetic variants affect how quickly individuals metabolize caffeine.
“As we expected, the decision to consume coffee is partly determined by individual genetic differences. Furthermore, we were able to confidently identify specific genes that influence coffee consumption, including some that affect how quickly caffeine is metabolized,” said Hayley HA Thorpe, lead author of the paper and an assistant professor at Western University.
The researchers also found positive genetic correlations between coffee consumption and various traits associated with substance apply. For example, individuals with a genetic predisposition to higher coffee consumption were also more likely to have genetic correlations with smoking initiation, alcohol consumption, and cannabis apply. This suggests a common genetic basis for coffee consumption and other substance apply behaviors.
In addition, the study found positive genetic correlations between coffee consumption and obesity-related traits such as body mass index (BMI). But “this only tells us that the genetics of coffee consumption are associated with the likelihood of obesity. While it may be that people with this genetic disposition drink more coffee and coffee consumption somehow increases the risk of obesity, there may also be indirect mechanisms at work,” Thorpe explained.
“For example, your genetics may make you more likely to drink coffee, but how do you drink the coffee you drink every day? Do you like it black, or do you only drink coffee drinks that are high in sugar and dairy? Our study didn’t look at how people prefer to drink their coffee, but regularly drinking these additives along with their coffee could also impact a person’s health.”
Interestingly, the study found significant discrepancies between the two cohorts in terms of genetic correlations with other traits. For example, in the 23andMe cohort, coffee consumption was positively correlated with anxiety-related traits, whereas in the UK Biobank cohort, these correlations were negative.
Similarly, cognitive traits such as executive function and intelligence showed positive genetic correlations with coffee consumption 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 genetic influences on coffee consumption in the US and the UK,” Thorpe said. “Our research design allowed us to examine other behaviours, 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 consumption and the apply of other medications and obesity. However, many other characteristics, such as mental disorders like anxiety, showed contrasting associations with the genetics of coffee consumption between the US and UK populations.”
Although the genetic correlations observed in the study were primarily for adverse outcomes, particularly substance apply disorders and obesity-related traits, this should not be misinterpreted to suggest that coffee itself is responsible for these effects.
“We don’t want anyone to conclude from this study that drinking coffee leads to better or worse health,” Thorpe explained. “Our study specifically focuses on genetics coffee consumption and what are the relationships between them genetics have with health. Our study confirmed that the genetics of coffee consumption may be simultaneously associated with health benefits AND “adversities, depending on what feature of health is being considered.”
“Our study also tells us that the health effects of the genetics of coffee consumption may vary greatly across different populations and contexts. The way someone drinks coffee and their drinking habits are likely key to its health effects. Whether coffee consumption is ‘good’ or ‘bad’ for someone likely depends largely on the individual, the context, and the health domain in question.”
The study provides valuable information on the genetic basis of coffee consumption, highlighting the significant role of genetic factors in shaping our coffee drinking habits. However, there are some limitations that should be considered. The study focused primarily on individuals of European descent, limiting the generalizability of the results to other populations.
The researchers also noted that different methods of measuring coffee consumption across cohorts may contribute to the observed discrepancies. For example, the 23andMe cohort specifically measured caffeinated coffee consumption, while the UK Biobank included both caffeinated and decaffeinated coffee.
Further studies should aim to replicate these findings in more diverse populations and investigate potential interactions between genetic and environmental factors on coffee consumption.
Tests, “Genome-wide association study of coffee consumption in UK and US participants of European descent reveals cohort-specific genetic associations”, by Hayley HA Thorpe, Pierre Fontanillas, Benjamin K. Pham, John J. Meredith, Mariela V. Jennings, Natasia S. Courchesne-Krak, Laura Vilar-Ribó, Sevim B. Bianchi, Julian Mutz, 23andMe Research Team, Sarah L. Elson, Jibran Y. Khokhar, Abdel Abdellaoui, Lea K. Davis, Abraham A. Palmer, and Sandra Sanchez-Roige.
