NBC News
There are certain studies that coffee lovers love.
Here’s one: Drinking several cups of caffeinated coffee or tea a day may protect against type 2 diabetes, coronary heart disease and stroke.
The findings, published Tuesday in the Journal of Clinical Endocrinology & Metabolism, add to existing research suggesting that daily coffee drinkers have better heart health than non-drinkers, as long as they don’t consume too much caffeine.
“Caffeine intake at different doses may have different health effects,” Chaofu Ke, a co-author of the study and an associate professor in the department of epidemiology and biostatistics at Soochow University in China, wrote in an email.
Ke and a group of researchers from China and Sweden analyzed the coffee and tea drinking habits of 188,000 people aged 37 to 73 from the UK Biobank, a large database containing anonymized health information, who had completed questionnaires about their beverage consumption over the previous 24 hours. They also analyzed the responses of about 172,000 people who specified that they drank caffeinated coffee or tea. None of them had a history of cardiometabolic disease (defined by a diagnosis of at least two of three conditions: type 2 diabetes, coronary heart disease or stroke) when the study began.
The researchers followed up with the participants after about 12 years.
Drinking two to three cups of coffee or up to three cups of tea a day was the sweet spot, the researchers found.
People who consumed between 200 and 300 milligrams of caffeine a day had a lower risk of cardiometabolic disease, compared with people who drank less than 100 mg a day. Coffee drinkers, in particular, had the lowest risk (a nearly 50% reduction), while people who consumed 200 to 300 milligrams of caffeine from tea or a mix of the two beverages were 40% less likely to develop cardiometabolic disease. For tea drinkers, cardiometabolic risk decreased the most in those who drank up to three cups a day, but the benefits diminished after that.
Even for people who consumed more than 400 mg of caffeine per day (just 4% of caffeine drinkers in the study), the stimulant did not appear to have negative consequences for their cardiometabolic health.
And among those who eventually developed a cardiometabolic disease, drinking moderate amounts of coffee every day was still associated with a lower risk of developing another cardiometabolic disease.
Moderate caffeine intake was also associated with certain metabolites (compounds produced when the body digests foods and drinks) that are linked to better heart health.
“Moderate caffeine intake can regulate the levels of these metabolites,” Ke said.
Dr. Luke Laffin, co-director of the Cleveland Clinic’s Center for Blood Pressure Disorders, said the findings need to be taken in context.
“It may give us an idea, but we can’t draw any conclusions,” said Laffin, who was not involved in the research. “Everything in moderation is probably the best way to go. If someone drinks a couple of cups of coffee a day, that suggests that the dose might be protective.”
However, some types of heart disease can make caffeine intake more dangerous, he said.
“Too many cups of coffee can raise blood pressure in someone who already has hypertension,” Laffin said.
Studies have also shown a link between high caffeine consumption and an increased risk of dementia and stroke. Other studies have shown positive links between caffeine and kidney health, type 2 diabetes, and heart failure.
Dr. Stephen Kopecky, a preventive cardiologist at the Mayo Clinic in Rochester, Minnesota, added that in addition to a person’s underlying health problems, the way a person consumes caffeine likely makes a big difference in how it affects their health.
“The message I don’t want to spread is that caffeine is good for you, so let’s have more of it. We’ve never found that taking what’s good in the diet and putting it in a pill is equally beneficial,” Kopecky said.
One important caveat to the study is that it only included people who regularly drank coffee or green or black tea, all of which contain hundreds or thousands of chemical compounds, only one of which is caffeine.
“All of these components are likely to have an impact, but they have to be together,” Kopecky said.
Although the researchers adjusted for some heart disease factors, such as smoking, obesity, exercise and diet, there is still much to learn about what other habits you may have besides drinking caffeine that could affect your risk.
“It’s hard to do a study that controls for everything,” Laffin said, adding that a cup of coffee a day is fine for most people.
Kopecky agreed, adding that consuming caffeine in energy drinks, which often have added sugar, artificial sweeteners and other additives, or in caffeine shots, is definitely something to avoid.
And when it comes to tea and coffee, keep it simple.
“People need to be scrupulous about what else is in their coffee besides caffeine,” Laffin said.
“If you go to your favorite coffee shop and order a coffee with whipped cream and sugary syrup, you are consuming a lot of calories, which may contribute to cardiometabolic disease.”
