“Coffee, I Must Have Coffee…”

Whether you reach for a Starbuck’s Venti — the “Big Gulp” of coffee servings — or a wee size cup of Joe in the morning, or none at all, might be influenced by your genes.

Two recently published studies found an association between coffee and caffeine consumption and SNP variants near the same two genes, CYP1A1 and AHR. One study looked at coffee consumption specifically; the other looked at all caffeine consumption including from tea, soda and chocolate, but coffee was by far the main source of caffeine for the participants.

Scientists from deCode Genetics in Iceland studied more than 10,000 coffee drinkers in European descent mainly in Europe. Their results published in Human Molecular Genetics in February pinpointed two SNPs near the CYP1A1 and AHR genes. The SNP rs2472297 near CYP1A1 had a fairly consistent effect — people with the T version were prone to drink about a quarter cup more of coffee a day, according to the study.

(23andMe customers can look up their data for rs2472297 and rs4410790 using the Browse Raw Data feature. 23andMe also looks at a variant that affects how quickly a person metabolizes caffeine. )

The other study, which was published in PLoS Biology and included more than 47,000 individuals with European ancestry living in the U.S., made similar findings, noting that people with two copies of a T at rs4410790 near the AHR gene drank  about a third of a cup of coffee more each day than those without any copies.

“Now, for the first time, we know specific genes that influence the amount of caffeine that individuals consume,” Dr. Neil Caporaso of the National Cancer Institute told the BBC. Caporaso, the co-author of study in the US, noted that while researchers know about associations between hundreds of genes and specific medical conditions, how those variants relate to dietary consumption is less well known.

Beyond that, both studies offer intriguing hints about how these two genes might interact, but more research is needed. In the meantime how people relate to their morning fix of java is well known, perhaps best summed up by Johann Sebastian Bach in his “Coffee Cantata:”

“How sweet the coffee tastes, more delicious than a thousand kisses . . . . Coffee, I must have coffee . . . . If I don’t get my three cups of coffee each day, I’ll shrivel up like a piece of roast goat.”