cup of coffee

Coffee lovers around the world who reach for their favorite morning brew probably aren’t thinking about its health benefits or risks. And yet this beverage has been subject to a long history of debate. In 1991 coffee was included in a list of possible carcinogens by the World Health Organization. By 2016 it was exonerated, as research found that the beverage was not associated with an increased risk of cancer; on the contrary, there was a decreased risk of certain cancers among those who drink coffee regularly once smoking history was properly accounted for. Additional accumulating research suggests that when consumed in moderation, coffee can be considered a healthy beverage. Why then in 2018 did one U.S. state pass legislation that coffee must bear a cancer warning label? Read on to explore the complexities of coffee.

Source Of

One 8-ounce cup of brewed coffee contains about 95 mg of caffeine. A moderate amount of coffee is generally defined as 3-5 cups a day, or on average 400 mg of caffeine, according to the Dietary Guidelines for Americans.

Coffee and Health

Coffee is an intricate mixture of more than a thousand chemicals. [1] The cup of coffee you order from a coffee shop is likely different from the coffee you brew at home. What defines a cup is the type of coffee bean used, how it is roasted, the amount of grind, and how it is brewed. Human response to coffee or caffeine can also vary substantially across individuals. Low to moderate doses of caffeine (50–300 mg) may cause increased alertness, energy, and ability to concentrate, while higher doses may have negative effects such as anxiety, restlessness, insomnia, and increased heart rate. [2] Still, the cumulative research on coffee points in the direction of a health benefit. [3,4] Does the benefit stem from the caffeine or plant compounds in the coffee bean? Is there a certain amount of coffee needed a day to produce a health benefit?

The bottom line: A large body of evidence suggests that consumption of caffeinated coffee does not increase the risk of cardiovascular diseases and cancers. In fact, consumption of 3 to 5 standard cups of coffee daily has been consistently associated with a reduced risk of several chronic diseases. [4] However, some individuals may not tolerate higher amounts of caffeine due to symptoms of jitteriness, anxiety, and insomnia. Specifically, those who have difficulty controlling their blood pressure may want to moderate their coffee intake. Pregnant women are also advised to aim for less than 200 mg of caffeine daily, the amount in 2 cups of coffee, because caffeine passes through the placenta into the fetus and has been associated with pregnancy loss and low birth weight. [3, 27] Because of the potential negative side effects some people experience when drinking caffeinated coffee, it is not necessary to start drinking it if you do not already or to increase the amount you currently drink, as there are many other dietary strategies to improve your health. Decaffeinated coffee is a good option if one is sensitive to caffeine, and according to the research summarized above, it offers similar health benefits as caffeinated coffee. It’s also important to keep in mind how you enjoy your brew. The extra calories, sugar, and saturated fat in a coffee house beverage loaded with whipped cream and flavored syrup might offset any health benefits found in a basic black coffee.

What about iced coffee?


Coffee beans are the seeds of a fruit called a coffee cherry. Coffee cherries grow on coffee trees from a genus of plants called Coffea. There are a wide variety of species of coffee plants, ranging from shrubs to trees.

  • Type of bean. There are two main types of coffee species, Arabica and Robusta. Arabica originates from Ethiopia and produces a mild, flavorful tasting coffee. It is the most popular type worldwide. However, it is expensive to grow because the Arabica plant is sensitive to the environment, requiring shade, humidity, and steady temperatures between 60-75 degrees Fahrenheit. The Robusta coffee plant is more economical to grow because it is resistant to disease and survives in a wider range of temperatures between 65-97 degrees Fahrenheit. It can also withstand harsh climate changes such as variations in rainfall and strong sunlight.
  • Type of roast. Coffee beans start out green. They are roasted at a high heat to produce a chemical change that releases the rich aroma and flavor that we associate with coffee. They are then cooled and ground for brewing. Roasting levels range from light to medium to dark. The lighter the roast, the lighter the color and roasted flavor and the higher its acidity. Dark roasts produce a black bean with little acidity and a bitter roasted flavor. The popular French roast is medium-dark.
  • Type of grind. A medium grind is the most common and used for automatic drip coffee makers. A fine grind is used for deeper flavors like espresso, which releases the oils, and a coarse grind is used in coffee presses.
  • Decaffeinated coffee. This is an option for those who experience unpleasant side effects from caffeine. The two most common methods used to remove caffeine from coffee is to apply chemical solvents (methylene chloride or ethyl acetate) or carbon dioxide gas. Both are applied to steamed or soaked beans, which are then allowed to dry. The solvents bind to caffeine and both evaporate when the beans are rinsed and/or dried. According to U.S. regulations, at least 97% of the caffeine must be removed to carry the decaffeinated label, so there may be trace residual amounts of caffeine. Both methods may cause some loss of flavor as other naturally occurring chemicals in coffee beans that impart their unique flavor and scent may be destroyed during processing.


  • Place beans or ground coffee in an airtight opaque container at room temperature away from sunlight. Inside a cool dark cabinet would be ideal. Exposure to moisture, air, heat, and light can strip coffee of its flavor. Coffee packaging does not preserve the coffee well for extended periods, so transfer larger amounts of coffee to airtight containers.
  • Coffee can be frozen if stored in a very airtight container. Exposure to even small amounts of air in the freezer can lead to freezer burn.

making coffee with coffee beans, a water carafe, and a cupMake

  • Follow directions on the coffee package and your coffee machine, but generally the ratio is 1-2 tablespoons of ground coffee per 6 ounces of water.
  • For optimal coffee flavor, drink soon after brewing. The beverage will lose flavor with time.
  • Use ground coffee within a few days and whole beans within two weeks.

Did You Know?

  • It is a myth that darker roasts contain a higher level of caffeine than lighter roasts. Lighter roasts actually have a slightly higher concentration!
  • Coffee grinds should not be brewed more than once. Brewed grinds taste bitter and may no longer produce a pleasant coffee flavor.
  • While water is always the best choice for quenching your thirst, coffee can count towards your daily fluid goals. Although caffeine has a mild diuretic effect, it is offset by the total amount of fluid from the coffee.


chemical formula for caffeine with three coffee beans on the side


Caffeine is naturally found in the fruit, leaves, and beans of coffee, cacao, and guarana plants. It is also added to beverages and supplements. Learn about sources of caffeine, and a review of the research on this stimulant and health.
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Last reviewed July 2020

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