Drinking coffee linked to lower risk of diabetes, heart disease and stroke, study finds. Here's how much you should be having.

Good news for coffee drinkers: People who have one to three cups a day face a lower risk of developing diabetes, heart disease and other cardiometabolic conditions, new research suggests. The study, published in the Journal of Clinical Endocrinology & Metabolism, also found a link between other types of caffeine consumption and lower risk of these diseases — but experts warn that not all caffeinated drinks are created equal when it comes to your health.

See below for the latest on why a morning cup of joe might actually be beneficial for you and the best way to optimize your caffeine consumption.

What the study found

The researchers used data from the UK Biobank — which contains statistics on the diets of more than half a million individuals between the ages of 37 and 73 — to compare people’s caffeine consumption and health outcomes. Specifically, they looked at the links between consuming coffee, tea or caffeine in general with how likely they were to develop two or more of three cardiometabolic diseases: type 2 diabetes, stroke and coronary heart disease.

They found that moderate caffeine drinkers — those having between one and three cups of coffee, or 100-300 milligrams of caffeine a day — were less likely than people who drank no caffeine or less than 100 mg a day to develop any of the three diseases. Risk was reduced by more than 48% for coffee drinkers, specifically. Those who drank a moderate amount of any caffeine were nearly 41% less likely to develop cardiometabolic diseases.

Benefits may be optimized around three cups of coffee per day, the study suggests. Those who drank this amount saw the greatest reduction in their risk of developing any one of the three diseases. And even after people were diagnosed with one of these diseases, moderate coffee drinking was still linked to a lower likelihood of eventually developing multiple cardiometabolic conditions (a common phenomenon; people with diabetes are between two and four times more likely to later have heart disease, per Johns Hopkins Medicine).

Tea drinkers, on the other hand, saw a reduction in their risk for type 2 diabetes, but not for stroke or heart disease, or for having multiple cardiometabolic diseases (the primary metric the researchers looked at).

Though experts say the study was of a high quality, they also underscore that the link shown between coffee or caffeine consumption and lower risk of these diseases doesn’t necessarily mean it proves that consuming these ingredients is responsible for protecting people’s health. “We have to look at the totality of evidence” from the many studies on coffee and caffeine, Dr. Luke Laffin, a preventive cardiologist with Cleveland Clinic, tells Yahoo Life. And that evidence doesn’t mean that coffee “is some cure for cardiovascular disease,” he says.

How might coffee or caffeine be protective?

Caffeine — in coffee or in any other food or drink— can be both friend and foe when it comes to heart health. The new study is only the latest to suggest a link between moderate consumption and heart and metabolic health. It’s not exactly clear why, but scientists theorize that it helps in several ways:

Dilating blood vessels: Caffeine may “relax the blood vessels,” says Laffin. However, it can also have the opposite effect. And for habitual coffee drinkers, it’s actually caffeine withdrawal that’s been linked to the opening of blood vessels, which allows blood to flow more efficiently, putting less stress on the heart and helping to keep blood pressure lower.

Lowering 'bad' cholesterol: Caffeine helps to keep levels of a protein known as PCSK9 relatively low, which in turn makes it easier for the liver to break down low-density lipoprotein (or "bad" cholesterol. Keeping bad cholesterol low is critical for good cardiometabolic health.

Coffee’s potential benefits are both more complex and better understood. Chiefly, coffee is loaded with antioxidants, including chlorogenic acid, Michelle Routhenstein, a dietitian who specializes in heart disease, tells Yahoo Life. “Coffee can be one of the only places that’s helping [some people] get antioxidants into their diet,” she notes.

The best way to consume coffee and caffeine

There can definitely be too much of a good thing when it comes to caffeine, experts tell Yahoo Life. “We never see a study that shows that drinking an energy drink helps cardiometabolic health,” says Routhenstein. “That’s too much caffeine, which can actually have negative effects on your cardiometabolic health,” such as raising your blood pressure and causing heart palpitations, she explains. Plus, there are a lot of other heart-unhealthy ingredients in soda and energy drinks, including often high doses of sugar or sugar substitutes and potentially harmful chemicals, such as those found in brominated vegetable oil.

When it comes to caffeine, “type and quantity are both important,” Routhenstein says. Coffee and tea are safer bets, but be aware that different types have different amounts of caffeine in them (though coffee generally contains more than tea). Routhenstein considers one to three cups of coffee a “good rule of thumb,” she says, but adds that not all cups are the same; a single 16-ounce mug is actually two servings. (For the record, the Food and Drug Administration recommends having no more than 400 mg of caffeine per day, and an 8-ounce cup of coffee contains about 96 mg of caffeine.).

And black coffee is best, experts say. “This [study] doesn’t mean you should drink the big caramel macchiato with all the sugar and whipped cream,” says Laffin. Have it with no additions, or with a little bit of milk or cream, he advises. (A pro tip from Routhenstein though: milk binds to antioxidants, making them less “bioavailable,” so you won’t be able to absorb as many of the beneficial nutrients.)

Routhenstein also warns that not everyone tolerates coffee well. Some people find it irritating to the stomach, or keep you up at night. And people with atrial fibrillation — a heart arrhythmia condition — should avoid coffee altogether. For people who react badly to coffee, Routhenstein recommends tea, even if the new study found it wasn’t linked to equally large reductions in risk of diabetes and heart disease.

And although the study’s results are encouraging, if you’re not a fan, that’s OK. “I don’t think I would say if you’re not drinking coffee that you absolutely should,” says Laffin. “For the average person, just try to enjoy your cup of coffee in the morning.”