People love coffee, which is partially explained by genetics, but you’d be forgiven for being less sure if your daily cup of joe is good for you.
Researchers have been wrestling with that question for years, studying the genetics associated with coffee consumption.
Wired
People are genetically wired to react differently to their morning coffee. Your genetics affect how you metabolize caffeine and your bitter taste perception, and both are associated with how much coffee you consume. Genetic differences can explain why some people can chug a Venti without problem, while a few sips are enough to perk up someone else all day long.
There are health implications for all this, but those are less clear-cut, and the data cuts both ways.
A recent study led by researchers at UC San Diego and Western University in Ontario, Canada, illustrates how complicated it is to understand the health outcomes of coffee consumption. The study found clear genetic associations with drinking coffee, but the same study found conflicting data around health outcomes. However, those divergent findings may say more about differences in culture or coffee culture than anything else.
Health Outcomes
The study, published in the journal Neuropsychopharmacology, used data from two sources: a cohort of about 330,000 people in the UK Biobank and another data set from about 130,000 23andMe customers who consented to participate in research.
“We used this data to identify regions on the genome associated with whether somebody is more or less likely to consume coffee, and then identify the genes and biology that could underlie coffee intake,” said Hayley Thorpe, the lead researcher on the study and a postdoctoral researcher at Western’s Schulich Medicine & Dentistry.
The data confirmed seven previously known genetic associations with coffee consumption. Some shared health outcomes were also found in both cohorts, but what was striking was where the health outcome data diverged. More than 80 percent of the outcomes were positive within the 23andMe data set, whereas only about 54 percent of the health outcomes were positive within the UK Biobank data set.
Coffee Culture
Pierre Fontanillas, a senior scientist of statistical genetics at 23andMe and one of the study’s lead researchers, said the stark differences in the health outcomes in the two datasets may be more related to the differences in the coffee culture between the UK and the United States.
“Your genetics influences your coffee consumption, but there are other factors, like culture and environment,” Pierre said.
Although the research participants from the UK Biobank and 23andMe have a lot in common, there are differences between the two groups that highlight just how complicated this kind of research can be. For instance, in the United States, serving sizes tend to be larger than in the UK. In addition, people in the US are more likely to add sweeteners or frothed milk to their coffee drinks, and they are more likely to augment their caffeine consumption with caffeinated sodas. Instant coffee is more common in the UK, serving sizes are small, and coffee drinkers may also increase their caffeine consumption with tea.
“That could explain some of those differences,” Pierre said.
While there were differences in health outcomes, health outcomes were also shared within both cohorts. Both showed genetic associations between coffee and harmful health outcomes such as obesity and substance use, for instance.
However, the two cohorts diverged when looking at other health and psychiatric traits.
“Look at the genetics of anxiety, for instance, or bipolar and depression,” said Thorpe at Western University. “In the 23andMe data set, they tend to be positively genetically correlated with coffee intake genetics. But then, in the UK Biobank, you see the opposite pattern, where they’re negatively genetically correlated. This is not what we expected.”
Learn More
23andMe’s Health + Ancestry Service can help you learn about genetic factors that may be involved. Order a kit, send us your spit, and find out what your genetics predict about your caffeine consumption level.