Harvard scientists say this is the exact amount of coffee you should drink every day to stay healthy

This article was updated on October 7, 2021.

You’ve probably heard about all the health benefits that come from drinking your daily cup of joe. You’ve probably also read about how coffee can be harmful to your body sometimes. So which is actually true? A study suggests the answer may be both.

The study, published in The New England Journal of Medicine (NEJM), reviewed 95 studies. The authors determined that limiting caffeine intake to about 400 milligrams (or four to five cups of coffee) per day was best, but that moderate consumption of coffee can still offer many health benefits.

Benefits of drinking coffee

It seems the benefits of drinking coffee far outweigh the negatives, though this was originally not thought to be the case. Early studies on coffee neglected to take into account certain factors. For example, many heavy coffee drinkers tended to use tobacco products and were fairly inactive.

Now that we’ve adjusted research to account for such things, the results show that not only is coffee pretty good for you, but it may even help you live longer.

“Caffeine is the first thing that comes to mind when you think about coffee. But coffee also contains antioxidants and other active substances that may reduce internal inflammation and protect against disease,” Diane Vizthum, M.S., R.D., research nutritionist for Johns Hopkins University School of Medicine, said.

According to John Hopkins Medicine, drinking coffee means you are less likely to die from coronary heart disease, stroke, diabetes, and kidney disease.

Coffee also contains several substances that have shown to protect against Alzheimer’s disease and Parkinson’s disease. For those who already suffer with Parkinson’s, it’s even been shown to help them control their movements better.

It’s also been associated with protecting against liver disease, strengthening DNA strands, reduced the risk of stroke, and protecting against type two diabetes.

“The evidence is pretty consistent that coffee is associated with a lower risk of mortality,” Erikka Loftfield, a research fellow at the National Cancer Institute said.

Dr. Giuseppe Grosso, an assistant professor in human nutrition at the University of Catania in Italy, told the New York Times that the benefits from coffee likely come from polyphenols. These plant compounds have antioxidant properties.

Risks of drinking too much coffee

However, even though coffee offers so many positive effects on health, it can also be detrimental when overdone. You may have even experienced that jittery feeling you get when you have four or five cups in a row.

According to John Hopkins Medicine, this feeling is due to the excessive amount of caffeine you’ve consumed. It can also lead to increased heart rate, high blood pressure, anxiety and insomnia.

However, these effects may not be consistent for everyone, as people process coffee and caffeine differently.

“Caffeine tolerance is different for everyone,” Vizthum said. “You want to do what makes you feel good. You can still get some of the potential health benefits by drinking one cup of coffee a day, or even by drinking decaffeinated coffee.”

Grosso explained that some people have a polymorphism, which can slow down their metabolism when it comes to caffeine. This means they really don’t need more than one coffee in a sitting.

“They take a coffee, and then they have the second and the third, and they still have the caffeine of the first,” he said.

It’s good to assess your tolerance for coffee and how much you actually need each day to reap the most benefits, without any of the negative side effects.

“I think that caffeine is so common and so ingrained in our culture, and daily habits, that we often don’t think about it as a potential source of problems,” Mary M. Sweeney, an assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine, said.

How to drink coffee the right way

So, what is the best rule of thumb when it comes to healthy, moderate coffee consumption?

Again, it seems to vary for most people. The authors of the NEJM study admit that some people can consume higher amounts of coffee with no issues whatsoever, while others feel jittery after more than one. However, there are a few things to consider when preparing your cup of java.

The way you prepare your coffee matters. If you’re loading up your coffee with heavy cream and sugar every day, you may not be reaping the biggest health benefits. Try using a non-dairy creamer and natural sweeteners instead.

“The bottom line is that coffee is one part of your lifestyle,” Vizthum said. “Some of the factors that make a bigger impact on your health are eating a balanced diet, exercising and maintaining a healthy weight. Drinking coffee should just be an addition to those key health factors.”

Another thing to consider is the way you make your coffee or the type of coffee you drink. Most coffee beans provide the same health benefits, but instant coffee has been shown to offer slightly less.

Marilyn C. Cornelis, an assistant professor in preventive medicine at the Northwestern University Feinberg School of Medicine, also said that boiled coffees, such as French press or Turkish coffee, may actually raise LDL, known as the bad cholesterol.

While the increase is not significant enough to be a concern for most people, for those who have cholesterol issues, it may be best to choose a coffee that is filtered.

As for the coffee pods that have grown in popularity, they seem to offer all the same health benefits as regular ground coffee beans.