There are certain studies that coffee lovers, well, love.
This is one of them: 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 nondrinkers — provided they don’t drink too much caffeine.
“Caffeine intake at different doses could have different health effects,” the study’s co-lead author Chaofu Ke, 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 in China and Sweden analyzed the coffee and tea drinking habits of 188,000 people ages 37 to 73 from the U.K. Biobank, a large database that contains anonymous health information, who had completed questionnaires about their beverage intake over the past 24 hours. They also looked at responses from 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 the 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 about 200 to 300 milligrams of caffeine daily had a lower risk of cardiometabolic disease, compared to people who drank less than 100 mg a day. Coffee drinkers, in particular, had the lowest risk — a nearly 50% reduction — while people who got the 200 to 300 milligrams of caffeine from tea or a mix of both beverages were about 40% less likely to develop cardiometabolic disease. For tea drinkers, cardiometabolic risk decreased the most for those who drank up to three cups daily, but the benefits tapered off after that.
Even for people who consumed more than 400 mg of caffeine a day — just 4% of the study’s caffeine drinkers — the stimulant didn’t appear to have negative consequences for their cardiometabolic health.
And among those who did eventually develop cardiometabolic disease, drinking moderate amounts of coffee every day was still associated with 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 may regulate levels of these metabolites,” Ke said.
Dr. Luke Laffin, co-director of the Center for Blood Pressure Disorders at Cleveland Clinic, said that the findings need to be taken in context.
“It can give us an idea, but we can’t draw any conclusions,” said Laffin, who wasn’t involved with the research. “Everything in moderation is probably the best way to do it. If someone is having a couple cups of coffee a day, this suggests that 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 intake and a greater 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 preventative cardiologist at the Mayo Clinic in Rochester, Minnesota, said that, in addition to a person’s underlying health issues, the way a person consumes caffeine likely makes a big difference in how it affects their health.
“The message I don’t want to get out there is that caffeine is good, so let’s take more of it. We have never found that taking what is good in the diet and putting it in a pill is equally beneficial,” Kopecky said.
An important caveat of 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 them being caffeine.
“It’s likely all of these components that have an impact, but they have to be together,” Kopecky said.
Although the researchers did adjust for some heart disease factors, such as smoking, obesity, exercise and diet, a lot remains unknown about what other habits they may have in addition to drinking caffeine, which could affect their risk.
“It’s hard to do a study that controls for everything,” Laffin said, adding that a daily cup of coffee is just fine for most people.
Kopecky agreed, adding that consuming caffeine in energy drinks, which often have added sugar, artificial sweeteners and other additives, or 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 aside from caffeine,” Laffin said.
“If you are going to your favorite coffee shop and ordering a coffee with whipped cream and sugary syrup, you’re consuming a lot of calories, which can contribute to cardiometabolic disease.”
