The Nuance

This Is the Healthiest Way to Drink Coffee

The optimal amount, preparation, and timing — according to the latest research

Gertrude Stein once wrote that coffee “is a lot more than just a drink; it’s something happening.”

The more experts study coffee, the more that “something” seems to be good for us.

Just this month, a large study in the journal PLOS Medicine found evidence that those who drink 1 to 3 cups of coffee a day enjoy a roughly 14% lower risk for stroke and about the same drop in dementia risk compared to people who abstain.

As usual, moderate consumption was associated with the greatest benefit. When people drank four cups or more, their risk for stroke and dementia drifted back toward baseline, the study found.

This same daily dose has appeared again and again in the coffee research, which at this point is robust and mostly positive. “The greatest benefits appear to be [with] about 3 to 5 cups per day,” says Walter Willett, MD, professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health.

Willett co-wrote a comprehensive research review on coffee and caffeine, which appeared last year in the New England Journal of Medicine (NEJM). Like the new PLOS Medicine study, his review found that coffee consumption may reduce a drinker’s risk for several major illnesses. The list includes Type 2 diabetes, neurological disorders, liver disease, heart disease, and cancers of the skin, breast, and prostate. Research has also linked coffee to mood and mental health improvements.

“It is unclear at this time whether lighter or darker-roast coffee has more benefits.”

How could coffee do so much for us? A lot of the health benefits may be attributable to caffeine.

Caffeine binds to receptors in the brain — specifically, adenosine receptors — that help govern the release of dopamine, epinephrine, serotonin, and other neurotransmitters. These hormones play a role in our sleep, appetite, energy, memory, and mood. While many of the specifics are murky, the effect caffeine has on adenosine receptors and their related brain chemicals may provide a mechanistic explanation for some of coffee’s apparent health benefits.

“In addition to caffeine, coffee has hundreds of other phytochemicals including the polyphenol chlorogenic acid, the vitamin B3 precursor trigonelline, lignans, and modest amounts of magnesium, potassium, vitamin B3, and fiber,” says Rob van Dam, PhD, first author of the NEJM review and a professor in the Department of Exercise and Nutrition Sciences at George Washington University’s Milken Institute School of Public Health.

Highlighting chlorogenic acid, he says that coffee is the main source of this polyphenol in most people’s diets, and it been shown in animal models to improve sugar metabolism. “This may explain why consumption of decaffeinated coffee has been linked to a lower risk of Type 2 diabetes, similar to caffeinated coffee,” he says.

To get the most out of your joe, he recommends going easy on cream and sugar. He also says that sensitivities to caffeine differ from person to person, and that some people experience anxiety or insomnia if they have too much of it. “It is thus useful for each coffee drinker to adopt a pattern of consumption that avoids these adverse effects, for example by avoiding large amounts at one sitting or avoiding coffee later in the day,” he says.

To his point, a 2015 study in the journal Science Translational Medicine found that drinking coffee three hours before bedtime caused circadian disruptions and a delayed release of the sleep hormone melatonin. This suggests that drinking coffee in the evening may interfere with the internal clocks and processes that help you fall asleep at your normal bedtime. On the other hand, a 2020 study found that drinking coffee in the morning or early afternoon does not seem to shift a habitual coffee drinker’s circadian system in ways that mess with evening melatonin release or sleep.

“Unfiltered coffee can increase blood cholesterol levels, so filtered coffee is healthiest.”

Van Dam offers a few more warnings. “Caffeine intake during pregnancy may reduce fetal growth, and possibly increase the risk of miscarriage,” he says. Also, the effect of caffeine on kids is not well-understood.

When it comes to the health effects of different styles of coffee, the research is spotty. “It is unclear at this time whether lighter or darker-roast coffee has more benefits,” van Dam says.

But Willett offers a word of caution about French-press coffee, Turkish coffee, and other preparations that eschew filtering. These types contain elevated levels of a coffee compound called cafestol, which may cause health problems. “Unfiltered coffee can increase blood cholesterol levels, so filtered coffee is healthiest,” he says.

Finally, his and van Dam’s research review identified some broad safety thresholds regarding caffeine intake. Roughly 400 mg per day, or about 200 mg per sitting, seems to be a safe upper limit. The average 8-ounce cup of home-brewed coffee contains 92 mg of caffeine, but coffee-shop coffee — which is often made with a higher grounds-to-water ratio — may contain double that amount of caffeine, according to figures in their study.

It’s hard to believe now, but until recently coffee was considered a health threat. While you should still steer clear of heavily sweetened “coffee drinks” — all those spiced lattes and cappuccino perversions sold at the big-name coffee chains — a couple cups of old-school joe seem like a healthy addition to your daily routine.