How Much Coffee Is Good for You? Scientists Believe Drink Could Cut Risk of Death Even in Large Amounts

Drinking coffee could cut the risk of death even in those who struggle to metabolize caffeine, scientists believe.

Researchers arrived at this conclusion after assessing the health of 500,000 people who took part in a study based in the U.K.

Past studies have indicated an inverse association between drinking coffee and the risk of developing chronic conditions such as heart disease, diabetes, Parkinson's and cancers of the liver, bowel, colon and endometrium. But evidence also suggests caffeine could cause high blood pressure or heart attacks in those who find it tough to metabolize. Also, what heavy coffee drinking—around six cups or more a day—does to the body also needs further investigation, the authors noted.

To shed light on these concerns, researchers delved into data from the U.K. Biobank study made up of 500,000 individuals across the U.K. between 2006 and 2010. The average age of participants was 57 years old, and 87 percent drank coffee. The data included demographic information, lifestyle choices and genetic details taken from blood, urine and saliva samples.

Dr. Erikka Loftfield, of the Division of Cancer Epidemiology and Genetics at the National Cancer Institute and author of the study published in JAMA Internal Medicine, told Newsweek: "How well caffeine is metabolized varies considerably from person to person.

"A few studies have suggested that coffee drinkers with polymorphisms indicating slower caffeine metabolism may be at increased risk of adverse health outcomes," she said, adding "the U.K. Biobank, a very large cohort study with data on coffee intake, other lifestyle factors, and genetics, allowed us to address this question for the first time."

During the period of the study, over 14,000 participants died. Researchers noticed an inverse association between drinking coffee and the risk of death, regardless of whether individuals metabolized it quickly or slowly. This correlation was found in individuals who drank one cup of coffee to as many as eight per day.

"Our findings suggest that inverse associations between coffee and mortality may be attributable to constituents other than caffeine," said Dr. Loftfield.

Related: Drinking this much coffee could help keep your heart healthy, study suggests

However, the team behind the study stressed they only found a correlation between coffee and a lower chance of death.

"Further research is needed to better understand the potential biological mechanisms underlying the observed associations of coffee with various health outcomes," Dr. Loftfield acknowledged.

The results support the recommendations of the U.S. Dietary Guidelines Advisory Committee, which states consuming three to five cups of coffee per day, or 400 milligrams per day, of caffeine is not detrimental to healthy individuals.

However, Dr. Loftfield advised, "While our findings may provide reassurance to coffee drinkers, they do not indicate that individuals should change their current coffee drinking preferences."

Dr. Robin Poole, a specialty registrar in public health at the University of Southampton who did not work on the study, told Newsweek the research is significant as it includes a very large sample of people from the general population, and data both on coffee consumption and genetics. However, he highlighted the findings could be at risk of inaccuracies due to unknown or unmeasured factors linking to drinking coffee and being in good health.

"While this research offers further reassurance to current coffee drinkers, people should not start drinking coffee purely in an attempt to become healthier," he advised.

"We know that some people metabolize caffeine quite slowly and are less tolerant of the apparent physical affects of caffeine, which of course comes from many sources other than coffee. Such people would be better to avoid too much coffee, or move toward decaffeinated choices, that this study has shown still have beneficial associations."

He added: "Healthier coffee, free from sugar or syrup, should also be encouraged to optimize any health benefit."