Health professionals have previously warned against drinking large amounts of caffeinated coffee, saying tit could lead to irritability and insomnia. But a number of studies have that drinking coffee is associated with a lower risk of disease or death. Taking this into account, researchers analysed data from 500,000 adults in the UK. This including genetic data because previous studies have suggested genetic factors in the rate at which the body breaks down caffeine. The previous research implied that drinking coffee was associated with a lower risk of death and that these genes made no difference to that.
That being said, it depended on how much coffee you drink. A person who drinks less than one cup a day would reduce the risk of death by 6% while 6 or 7 cups reduced the risk by 16%. For some people this may be too small a difference to justify drinking more. It also found that it didn’t matter whether you had been drinking caffeinated or decaffeinated coffee. That being said it is recommended that you “stick to decaf in the evening” because sleep deprivation is far more serious.
This research came from the National Cancer Institute and National Institutes of Health in Maryland, USA and used data obtained from a number of institutions including the UK’s Medical Research Council and the British Heart Foundation. The study was published in the peer-reviewed medical journal JAMA Internal Medicine.
It involved data from 498,134 participants in the UK Biobank study which involved people aged 40 to 69 throughout the UK between 2006 and 2010. Participants filled out a questionnaire that included dietary assessments as well as smoking habits, alcohol consumption, tea drinking habits, and BMI. It also involved physical examinations and biological samples, including genetic samples, were provided. Participants were asked about their daily coffee consumption, how many cups and what type of coffee they consumed, decaf, instant, or ground.
The researches looked at the genetic data that was available for most of the participants and gave them “caffeine metabolism scores” to highlight whether they were fast or slow caffeine metabolisers.
All the participants were followed up from when they joined the UK Biobank until their death or the 2016 census, whichever came first. Over the 10 years of follow-up, 14,225 died. Overall, coffee drinking was found to be inversely associated with the overall risk of death meaning that the more coffee was drink, the lower the risk of death.
It is important to note that this did not come from a study that was set up to look at this question in detail so it does not prove direct cause and effect between mortality and coffee drinking. There may be other dietary, health, and lifestyle factors and since the coffee intake was self-reported, it may not be entirely accurate. Since the data involved those over 40 it may be different for a younger population.
The NHS advises against drinking more than eight cups a day unless you’re having decaf as the high caffeine intake would be very high. Pregnant women are advised to have no more than 200mg of caffeine a day, equivalent to 2 mugs of instant of 1.5 mugs of filter coffee.