Will your caffeine metabolism affect whether coffee is good for you?

Despite the incredible amount of evidence that coffee is good for you, people continue to act as if it's not just a guilty pleasure, but one that's actively bad for you. The fact is that more and more evidence shows that coffee, whether regular or decaffeinated, instant, drip, espresso, or brewed in some other way, is good for you.

Most recently there's been concern that those who metabolize caffeine more slowly than others might have an increased risk of heart disease, and that those who drink 6 or more cups of coffee per day might be affected differently than those who drink less coffee.

Fortunately a team of scientists in the United Kingdom were able to make use of information relating to coffee consumption as well as health and demographic information for almost half a million (~500,000) enrolled in the UK's National Health Service (NHS) (JAMA Int Med doi:10.1001/jamainternmed.2018.2425). The participants in this study were between 40 and 69 years of age at the time of enrollment (between 2006 and 2010) and responded to a detailed questionnaire that included questions regarding smoking history; alcohol, tea, and coffee consumption; physical activity; and race/ethnicity.

Questions about coffee asked not only how many cups of coffee the respondent drank every day, but also distinguished between the different ways coffee can be prepared, from instant coffee to drip or espresso, and included whether that coffee was caffeinated or decaffeinated.

Further, the participants underwent genetic testing that generated "caffeine metabolism scores" - essentially whether they metabolized caffeine faster or slower than others.

After the close of the study near the end of 2015, the authors accessed the NHS' records to see which participants had died over the course of the study, then classified those deaths into one of three broad categories: cancer, cardiovascular (heart) disease, or respiratory disease.

After taking into account the variables mentioned above, the authors found that an individual's caffeine metabolism score had no significant effect on their risk of death from any cause, regardless of how much coffee they drank, whether it was caffeinated or decaffeinated, or how the coffee was made. (They note that a faster caffeine metabolism was was slightly associated with a higher risk of all-cause mortality, but that the association was "weak.")

Overall, greater coffee intake meant a lower risk of death, even for those who drank 6 or more cups of coffee per day. Compared to those who did not drink coffee, those who drank 2-5 cups of coffee per day had a 12% lower risk of death, while those who drank 6-7 cups per day were 16% less likely to die of any cause.

What this means for you

If you like your coffee, drink it. This research suggests that it doesn't much matter what kind of coffee you drink - whether it's instant coffee or drip, regular or decaf. (Interestingly, 55% of the study's participants drank instant coffee.) Just because coffee is good for you, however, that doesn't mean that adding sugary flavorings, whether a shot of syrup, a hit of whipped cream, or just a bunch of table sugar, will be counteracted by coffee's positive effects. Drink it as plain as possible most of the time and treat the ultra-sugary drinks as the desserts they truly are - something for now and then, not every day.

First posted: July 18, 2018