Nearly eight out of 10 people are coffee drinkers, according to the National Coffee Association's 2016 report. And like anything that's part of our daily ritual, we have burning questions -- like, is coffee good for you or bad for you, or both? USC experts weigh in.
Over the years coffee has been blamed for causing everything from high blood pressure and high cholesterol (and thus heart disease) to pancreatic cancer, fibrocystic breast disease, and bone loss. The main focus has been on caffeine, one of the most extensively studied substances in food. But in nearly every instance early research linking coffee or caffeine to health problems has been refuted by better subsequent studies. "Not guilty" has repeatedly been the verdict. The pendulum has swung so far that some researchers now suggest that coffee may actually have health benefits.
Is Coffee Bad For You?
Coffee is known to have anti-cancer properties as researchers have found that coffee drinkers are typically 50% less likely to get specific cancers than nondrinkers. Several studies have found ties to lower rates of breast and rectal cancers. A large-scale cohort study of nearly 1,000 cancer patients has shown coffee prevents the recurrence of colon cancer.
From fighting free radicals, to improving memory, diabetes, parkinsons, and even reducing cancer risk, there are plenty of studies touting the health benefits of coffee.
Drinking coffee can also reduce the risk of liver and skin cancer. And recently, USC researchers also concluded it could reduce chances of developing colorectal cancer. "The more coffee consumed, the lower the risk," said Stephen Gruber, director of the USC Norris Comprehensive Cancer Center.
Writing in the Journal of Clinical Oncology, research revealed data that suggests participants consuming four or more cups of coffee a day (equivalent to around 460 milligrams of caffeine), were 42% less likely to have their cancer return than non-coffee drinkers, and were 33% less likely to die from cancer or any other cause during the study follow up period.
"We found that coffee drinkers had a lower risk of the cancer coming back and a significantly greater survival and chance of a cure," said lead author Dr Charles Fuchs -- who is director of the Gastrointestinal Cancer Center at the Dana-Farber Cancer Institute.
On top of that, researchers from Harvard have found coffee protects against cardiovascular disease, depression in women and even cuts suicide risk in half.
Can coffee stunt your growth?
"It does not -- bottom line," said Roger Clemens, a pediatric nutrition expert and adjunct professor at USC School of Pharmacy. The real issue, Clemens said, is allowing caffeinated beverages to take the place of nutritious food, especially during pivotal periods of growth and development. But, a cup of coffee here and there -- "probably no harm, no foul," he said.
Just like adults, children can react to caffeine differently, so paying attention to the amount and frequency are important. But if the child has a healthy diet, one could argue that an occasional cup of coffee may be considered a healthier alternative to some other beverages like soda.
And how did the myth of stunted growth come about? Clemens said expectant mothers have long been told to watch their coffee intake, because in some circumstances -- fewer than 10 percent -- babies can be born underweight due to issues metabolizing caffeine. It's possible that advice circulated and morphed into child development tips. Whatever the case, adult coffee drinkers now know: If you're 5-foot-5, you're 5-foot-5 -- and it's not because of that Folgers with grandma.
Does it make you poop?
It sure can. Researchers say a few factors play a part in why coffee may have you running to the restroom. For one, caffeine is a stimulant. "That's going to prime the body to get things going," said William DePaolo, an associate professor at Keck School of Medicine of USC. Coffee's acidity could spark the production of gastric acid, which signals the stomach to move things faster.
For the most part, however, DePaolo said, it's largely personal. Some people may be ultra sensitive and run to the loo like clockwork, while others may not.
Can you overdose from coffee?
For the most part, no. "It would be really, really difficult to overdose on caffeine," DePaolo said. "It would be a lot of coffee." He said coffee metabolizes too quickly in the blood so a large amount -- such as 75 to 100 cups -- would have to be consumed to OD. Known overdoses usually combine energy drinks, pills or soda, he said.
Occasional drinkers may feel mild indicators of toxicity -- your body telling you to slow down on the java -- such as being jittery, nervous and having blurred vision and increased heart rate, he said. Moral of the story: Just watch your intake -- and according to the federal government, three to five 8-oz. cups a day is A-OK.
Is Coffee Addictive?
Although some people get withdrawal symptoms from cutting coffee cold turkey, it's not addictive like, say, an opiate or alcohol, said Antoine Bechara, an addiction expert and psychology professor at the USC Dornsife College of Letters, Arts and Sciences. "There are similarities but these things -- they get embellished," he said. Coffee does cause an indirect increase in dopamine in the brain -- the same way cocaine does, just milder.
The key difference between coffee and a hard drug is that the latter requires a lapse in decision making -- ignoring your conscience, a key criteria in diagnosing addiction. Coffee is accepted by society and its use doesn't have significant fallout, compared to using a hard drug that could have physical, legal and financial ramifications, he said.
Is sipping on super-hot coffee bad for you?
Yes, it's true: There is such thing as too-hot coffee. USC researchers found drinks including coffeee, tea and yerba mate hotter than 149 degrees Fahrenheit could put drinkers at higher risk for cancer of the esophagus. For comparison, when McDonald's was smacked with its infamous hot coffee lawsuit in 1994, the coffee it served around 180 degrees. Luckily, coffee in the U.S. is usually served around 140 degrees, perfect temp for the ol' gullet.
Can it Be Decaf?
Many people reasonably opt for decaffeinated coffee due to allergies, increased anxiety, heart rate and nervousness. However, if you are avoiding the caffeine in coffee for reasons unrelated to negative symptoms, you're likely not doing your health any favors. Not only is decaffeinated coffee unnatural and highly processed, but is has also been found to increase blood lipids that raise the risk of heart disease.