September 29th is International Coffee Day, and we want to celebrate by sharing the little-known health benefits of coffee. So pour yourself a cup of joe and read on to learn the many advantages of drinking coffee.

The average American drinks two to three cups of coffee every day. Why? For most of us, it’s the caffeine—the most popular psychoactive drug in the world. The caffeine in coffee is what wakes us from morning grogginess, brightens our work breaks, chases away late-afternoon energy slumps, and keeps us up at night.

We may love coffee for the way caffeine makes us feel, but the rich aroma and delicious flavor actually comes from the many other phytochemicals (natural plant compounds) coffee contains. Caffeine itself is tasteless and odorless—and most of the health benefits of coffee apply to decaf as well.

The Health Benefits of Coffee

Among the advantages of consuming a couple of cups or more of coffee daily are a lower risk of the metabolic syndrome and type 2 diabetes, Parkinson’s disease, liver cancer, cognitive impairment, and heart disease. There’s also some good evidence that coffee has a beneficial effect on your gut microbiome.

The value of coffee is so clear that the current Dietary Guidelines for Americans says that moderate consumption (three to five 8-ounce cups a day, or up to 400 mg of caffeine a day) can be incorporated into a healthy eating style. Beware elaborate coffee-based drinks, however. A cup of brewed black coffee has only about 3 calories, but at Starbucks, a 16-ounce caramel macchiato with soy milk contains 34 grams of sugar and runs to 320 calories.

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What’s in Your Coffee Cup?

Let’s start with coffee’s most obvious benefit, caffeine.

Caffeine is a natural stimulant that’s found in more than sixty plants, including coffee beans, tea leaves,  kola nuts (the flavoring for colas), and the cacao pods used to make chocolate. Synthetic caffeine, the only drug that can legally be added to food and drink, is used in energy drinks and snacks, some soft drinks (Mountain Dew, for example), and in some cold medicines and pain relievers.

Caffeine revs up your central nervous system, making you feel more awake and giving you an energy lift. How does it work? When you’re awake, neurons in your brain are active and produce a substance called adenosine as a byproduct of normal metabolism. When you get tired and slow down, your brain is less active and produces less adenosine. Special adenosine receptors in your body sense the slowdown and send signals telling you to relax and prepare for sleep. Caffeine perks you up again by blocking the receptors. It fools them into thinking you’re not tired because you’re still making plenty of adenosine. The receptors don’t send slow-down-and-sleep signals and you feel more alert and energetic.

How Much Caffeine is in an 8-Ounce Cup of Coffee?

The amount of caffeine in an eight-ounce cup of coffee can vary considerably, depending on the type of coffee, how it’s roasted, and how it’s brewed. That’s why an eight-ounce cup of coffee can contain anywhere from 95 to 200 milligrams of caffeine. Coffee made from Arabica beans (used in about 70 percent of the world’s coffee) has less caffeine but more beneficial phytochemicals than coffee made from the stronger-tasting robusta beans. 

How the beans are roasted doesn’t affect the caffeine content much—dark roasts have about the same caffeine as lighter roasts. The brewing method also matters. Standard drip-method coffee has about 100 mg of caffeine per cup. Espresso has up to 200 mg caffeine per cup, but the serving is usually much smaller than that. The coarse grind needed for French press coffee means that this method releases the least amounts of caffeine and phytochemicals. 

For comparison, most energy drinks have between 70 and 100 mg of added caffeine per 8 ounces; an 8-ounce cup of brewed tea contains anywhere from 15 to 60 mg. A cup of matcha has about 30 to 70 mg. Cola sodas contain about 35 mg in a 12-ounce can.

Black coffee has no fat, protein, or sugars. It’s a surprisingly good source of fiber—one cup of drip-brewed coffee has about 1.1 grams of soluble fiber. That may not sound like much per cup, but most Americans get only about 15 grams of fiber a day, or just half the recommended daily amount. (Of course, if you eat a plant-based diet, you’re probably getting at least 30 grams of fiber and probably more every day.) Multiplied by several cups a day, even 1.1 grams per cup is a valuable contribution toward your daily fiber recommendation.

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One cup of coffee also Contains: 

Riboflavin (vitamin B2): 0.01 mg, or about 11 percent of the RDA

Niacin (vitamin B3): 0.7 mg, or about 2 percent of the RDA

Potassium: 92 mg, or about 3 percent of the RDA

Magnesium: 8 mg, or about 3 percent of the RDA

Again, the amounts per cup are relatively small, but when multiplied by several cups a day, they add up.

Antioxidants from a Coffee Mug

The caffeine, fiber, vitamins, and minerals in a cup of coffee all contribute to your health, but perhaps the most important contribution comes from the many different organic compounds found in coffee. Many function as antioxidants in your system, quenching the damaging free radicals your body constantly produces as part of its normal metabolism. Free radicals are a major cause of inflammation—and inflammation is the underlying cause of many chronic health conditions, including type 2 diabetes, heart disease, cognitive impairment, and other issues. In fact, according to the Dietary Guidelines Advisory Committee, “Coffee consumption was associated with reduced risk of total mortality (3–4% lower mortality with 1 cup/day), especially cardiovascular mortality.” That puts coffee way ahead of other superfoods with high antioxidant content, like blueberries and kale.

Brain Benefits of Coffee

In 2015, researchers from the Women’s Health Initiative Memory Study looked at the relationship between caffeine intake from coffee and the risk of cognitive impairment or dementia in women aged 65 and older. They found that the women who consumed the most caffeinated coffee (the equivalent of more than two cups a day) were about 25 percent less likely to develop dementia or cognitive impairment compared to the women who consumed the least (less than a cup a day). Clearly, a couple of cups of coffee every day helps protect older women against memory issues and other problems that age can bring.

Microbiome Benefits of Coffee

Having a diverse range of bacteria is key to a healthy gut microbiome—the vast community of bacteria and other microorganisms found mostly in your colon.  You need a healthy microbiome for normal digestion and a strong immune system, but it influences almost every other aspect of your health as well. In general, coffee drinkers seem to have more diversity in their gut bacteria compared to non-coffee drinkers—and the more coffee you drink, the more diverse your microbiome.  2019 study in the American Journal of Gastroenterology shows that heavy coffee drinkers have higher levels of anti-inflammatory gut bacteria and lower levels of potentially harmful bacteria. An interesting aspect of the study is that the heavy coffee drinkers had healthier gut microbiomes regardless of how healthy their diet was in general.

Ethical Coffee

Most of the coffee we drink is grown in Central and South America and in Africa. Unfortunately, coffee cultivation can be very damaging to the environment. The coffee is often grown on cleared tropical forest using large amounts of chemical fertilizer; the plants are heavily sprayed with a range of pesticides; labor practices can be exploitative.

You can avoid contributing to these problems by buying coffee grown under ethical standards. At a minimum, ethical coffee is USDA organic and Fair Trade Certified. The best way to be sure you’re getting ethical coffee, however, is to look for the Bird-Friendly Certified logo on the package. This certification is awarded only by the respected Smithsonian Migratory Bird Center. It means the coffee meets their very strict requirements for ethical, shade-grown beans—you’re helping the environment every time you enjoy a cup.