Morning coffee. — Image © Tim Sandle
One scientific study on the benefits of drinking coffee is usually outweighed by another that shows neutral or harmful effects. What is the right answer? When it comes to genetics, the answer is complicated.
Of course, the answer to this question depends on how much coffee you drink. The upper limit of safe consumption is considered to be six cups of coffee per day. But is it more complicated than that and does the answer apply to a specific person?
Although the impact of coffee consumption on human health remains a controversial issue, one thing is certain: coffee is a psychoactive substance.
Researcher Sandra Sanchez-Roige, Ph.D., of the Department of Psychiatry at the University of California, San Diego School of Medicine, leads a team examining the coffee consumption characteristics of individuals in the 23andMe database.
The research team collected genetic data, as well as self-reported data on coffee consumption, to conduct a genome-wide association study. The idea was to link genes known to be associated with coffee consumption to health-related traits or conditions.
The researchers used this data to identify regions of the genome associated with greater or lesser likelihood of consuming coffee. From this, they set out to identify the genes and biology that might underlie coffee consumption.
The data suggests that the specific gene variants a person inherits from their parents influence how much coffee they are likely to drink.
Sanchez-Roige says the influence of genetics on coffee consumption was the first of two questions the researchers wanted to answer.
“The second thing is something coffee lovers really want to learn.” she translates. “Is drinking coffee good or bad? Is it associated with positive health outcomes or not?”
The answer is not final. The group’s genome-wide association study of 130,153 23andMe study participants in the US was compared to a similar UK Biobank database of 334,649 British people, revealing consistent positive genetic associations between coffee and harmful health outcomes such as obesity and substance employ.
A positive genetic association is an association between a specific gene variant (genotype) and a specific condition (phenotype).
Conversely, a negative genetic association is a perceptible protective trait, discouraging disease development. The findings become more complicated when it comes to psychiatric conditions.
The association between genotype and phenotype was also found to be more distinct than the association between coffee and tea.
A factor influencing the interpretation of the data is that coffee comes in many forms – from instant to Frappuccino – and is consumed within cultural norms that vary from place to place.
The researchers concluded that further research is needed to uncover the links between genetics and the environment, focusing not only on coffee/caffeine consumption but also on issues related to the employ of other substances.
So for now, the question about coffee and its impact on health remains unanswered.
The research appears in the journal Neuropsychopharmacologytitled “Genome-wide association study of coffee consumption in participants with European ancestry from the UK and US uncovers cohort-specific genetic associations.”
