Coffee. We sip it, slurp it, demand it, flavor it, all while debating its benefits. Drink in these health answers from the caffeine experts.
Have you heard the latest news about coffee? It can be hard to keep straight on whether coffee is A, good for you; B, not so good; or C, it depends on who’s drinking it; D, all of the above; or E, none of the above.
It’s enough to make you run out and order a double-shot espresso.
In the interest of coffee drinkers everywhere, here are the latest thoughts from leading researchers about coffee and whether it can enhance—or not—our health. We are “spilling the beans” on who should and shouldn’t be drinking coffee, especially if you suffer from certain conditions.
Coffee and the Dehydration Myth
Scientists define coffee as a “mild diuretic.” Drink it, they say, and you will increase your urine output and likely multiply your number of daily bathroom runs.
Until recently, scientists also generally agreed that drinking coffee causes dehydration. This seems logical: By urinating more often and in greater volume, you’re draining the body of precious fluids, right?
Wrong, according to Lawrence Armstrong, a professor of exercise and environmental physiology at the University of Connecticut.
In 2005, Armstrong and his colleagues conducted an 11-day controlled study of 60 males to examine the body’s response to caffeine intake. For the study’s first six days, all 60 men ingested roughly 226 milligrams of caffeine (the equivalent of two cups of brewed coffee) each day. On the study’s seventh day, the scientists separated the participants into three different groups: Twenty men maintained their present caffeine intake, 20 men doubled their caffeine intake to about 452 milligrams of caffeine (about four cups of coffee) per day, and the remaining 20 men avoided all caffeine until the study’s conclusion. For every participant, researchers monitored 20 different indices of hydration, including variables in the body, blood and urine.
At the end of the experiment, all 60 men still had similar hydration variables, says Armstrong. The study’s results, published in the International Journal of Sports Nutrition and Exercise Metabolism, suggest that drinking moderate amounts of caffeine does not lead to dehydration.
As Armstrong explains it: “Caffeine creates a diuretic effect in the body, this is true. But a diuretic effect is not the same thing as whole body dehydration. What caffeine does is cause a brief increase in urine output followed by a decline.”
Imagine, the scientist says, that you drink a liter of water. In the period immediately following this feat, your urine output will increase and then eventually decline. “Does this mean you are dehydrated?” Armstrong asks.
The answer, of course, is no.
More research must be done to determine if high concentrations of caffeine or chronic coffee consumption leads to dehydration. But in the meantime, coffee drinkers, enjoy your java in moderation, and count each cup of coffee as roughly equivalent to the same amount of water.
Coffee’s Disturbance at Night and Naptime
Caffeinated coffee is a stimulant, and when consumed late in the day it can result in a very restless night of sleep. Studies have found that caffeine can reduce a person’s perceived quality of rest and their total minutes spent in slumber. It also can increase the number of times a person wakes throughout the night. Still, many people choose to drink coffee after dark in hopes of warding off fatigue during graveyard shifts, late nights out and overnight study sessions.
However, the scientific world recently discovered that the effects of caffeine disturb daytime sleep more than nocturnal sleep. If you’re a night owl hoping to recover your rest during daylight—good luck. According to researchers at the University of Montreal, you’ve already got two strikes against you.
In the 2006 study, published in the Journal of Neuropsychopharmacology, Canadian scientists divided 34 moderate caffeine consumers into two groups. Half of the participants followed their normal nocturnal sleep schedule, while the remaining participants altered their sleep patterns to stay awake during the night and then “recover” by sleeping the next morning. All participants consumed either a placebo or 200 milligrams of caffeine in the hours before “bedtime.”
Members of the caffeinated, recovery group slept for a shorter period of time and spent fewer minutes in deep sleep relative to the study’s other participants. Scientists liken this scenario to a biological one-two punch. Caffeine consumption shallows a person’s sleep, thereby making it increasingly difficult to ignore nature’s circadian alarm clock. The end result, it seems, is a relatively uneasy session of recovery sleep.
Reflux Reaction: Coffee Wrongly Blacklisted?
For years, doctors have asked clients suffering from gastroesophageal reflux disease (GERD) to avoid a variety of foods—namely anything spicy, acidic, fatty or fried—in hopes of easing their symptoms. Coffee is on this list because of the belief that it relaxes the trap door to the stomach, thereby allowing acid to travel where it shouldn’t. Recently, however, a few studies have suggested that java’s long-standing blacklist might be unfair.
GERD—also called acid reflux disease—occurs when the stomach’s contents, including stomach juices, flow back into the esophagus. The most common symptom of GERD is heartburn, but other symptoms include nausea, gagging, coughing and hoarseness.
In 2005, Swedish researchers published the results of a study involving more than 3,000 individuals that aimed to evaluate the impact of various lifestyle factors on heartburn. The scientists found that smoking and sodium-rich diets strongly increase a person’s risk for GERD, but consuming coffee, tea and alcohol do not.
Also, just last year in the Archives of Internal Medicine, three Stanford University physicians published the results of a massive literature survey that included GERD studies from around the world, dating as far back as 1975. In this survey, the doctors concluded that there currently is no evidence to support the notion that a strict GERD diet reduces symptoms of heartburn.
What the evidence does support, according to the physicians, is that only two lifestyle changes result in a reduced risk for GERD—losing weight and elevating your head during sleep. Still, this new finding—that diet may have very little to do with heartburn—runs counter to the recommendations of the American College of Gastroenterology, which advocates for a change in eating habits to reduce GERD risk. In general and until more studies prove otherwise, the blacklist remains in place. Many doctors advise that if coffee worsens your GERD—and you all know who you are—avoid it, no matter what the latest survey says.
The Dangers of Decaf for Your Cholesterol
Decaffeinated coffee may be short on caffeine, but it’s got plenty of diptenes—and that may be bad news for your health.
In a three-month study spearheaded by Dr. Robert Superko of the Fuqua Heart Center in Atlanta, scientists randomly assigned 187 volunteers to one of three groups. Sixty-six people drank three to six cups of caffeinated coffee per day, 62 people drank three to six cups of decaffeinated coffee per day, and the remaining 59 people avoided both types of coffee. All coffee drinkers followed specific brewing instructions and drank their coffee black. Meanwhile, the researchers kept tabs on a slew of health statistics, including total cholesterol, markers for HDL and LDL (or “good” and “bad” cholesterol, respectively), and blood pressure.
The results of the study, which Dr. Superko presented to the American Heart Association in 2005, suggest that drinking decaffeinated coffee leads to a rise in bad cholesterol whereas drinking regular coffee does not.
How does the physician explain decaffeinated coffee’s potentially unhealthy side effect? “The species of bean used for decaf is different,” says Dr. Superko. “Decaf is usually made out of the robusta bean and regular coffee out of the arabica bean.” Unlike the arabica bean, robustas have a relatively high concentration of fats called diptenes, and these fats contribute to the increase in blood cholesterol, he says.
And while this rise in cholesterol is scientifically significant, it’s pretty small, roughly a change of about 10 points. “If your total cholesterol was 200, and you stopped drinking decaf, your total cholesterol could go from 200 to 190,” Dr. Superko says.
This is not a monumental drop in cholesterol, the physician points out. “But if you have high cholesterol and you’re trying to get it down and you drink a lot of decaffeinated coffee, try stopping the decaffeinated coffee,” he says. “This can help.”
Monitoring Blood Pressure: Decaf, OK; Regular, Be Wary
In the same experiment about cholesterol explained in the above section, Dr. Superko and his colleagues also investigated the link between coffee drinking and hypertension. The scientists measured blood pressure values four times every hour for all individuals involved in their study. This time, decaffeinated coffee came out on top.
“In the decaffeinated coffee group, blood pressures did not change,” Dr. Superko says. “But in the group drinking caffeinated coffee, their blood pressures went up significantly between 10 a.m. and 2 p.m.”
“It’s not the end of the world. If you don’t have high blood pressure, drinking one or two cups of coffee a day isn’t going to do anything,” says Dr. Superko. “But if you have high blood pressure, it’s important.”
The doctor recommends that people with hypertension cut coffee and other caffeinated beverages from their diet. As he puts it, “This is all part of a larger, healthy lifestyle approach to lowering your blood pressure.”
Breakfast Drink of Champions? Coffee and Your Workout
Picture this. You’re running your first 5K in years, and you’ve promised your younger brother (who runs marathons for fun) that you’ll be able to keep pace. One hour before race time, you head to the local coffee shop and order a medium-sized Sumatran black brew.
Are you dooming yourself or doing your body a favor?
According to the University of Connecticut’s Armstrong, coffee can be a superb pre-race snack.
“Caffeine stimulates your central nervous system; it enhances the force of muscle contractions and improves your power output,” says Armstrong. “It also impacts you psychologically; it makes you feel more alert …. it improves your mood.”
But to reap coffee’s edge, you must drink by the rules. Here, we review the latest who, what and when of java-juiced athletic performance.
First, the who:
“Caffeine benefits the endurance athlete,” Armstrong says. “It’s for the weekend warriors, the rowers, cyclists, swimmers and runners who cover long distances. It is not for sprinters,” he says. “It seems to have no effect on events that are less than 90 seconds long.”
In fact, coffee gives exercisers its biggest boost when the workouts are four to 20 minutes long and the intensity is high (a 7 or above on an intensity scale of 1 to 10, with 1 being sitting on the sofa), says Armstrong. But what about the world’s mellower athletes—is there nothing in a cup of coffee for them?
Don’t sweat it, Armstrong says: “If someone works out at 40 to 50 percent of their maximum [intensity], drinking caffeine is probably not going to help them physically, but it will affect their alertness and their mood, and this will translate to a better workout.”
Next, the what:
To be clear, what we are discussing here, right now, is a straight-up black caffeinated brew. And to get the perfect performance kick, the average 150-pound athlete should drink anywhere from two to three mugs of brewed coffee in one sitting, according to Armstrong. This averages out to about 300 to 500 milligrams of caffeine, he says.
But, when?
“If you are going to use coffee to help you with exercise, drink it one hour before your workout,” says Armstrong, because caffeine needs about 60 to 90 minutes to work its way into your bloodstream.
And when it does, cue the Rocky music and aim for a personal best.
Coffee Dos and Don’ts for Diabetics
Science suggests that coffee can be both good and bad for your health, depending on who you are. Read on to find out who should—and shouldn’t—drink up.
Who shouldn’t:
James Lane is a professor of medical psychology at Duke University. He is also one of only a few scientists in the nation now studying caffeine’s effects on glucose in patients with Type 2 diabetes. “Typically, in people with Type 2 diabetes, there is a large and persistent rise in glucose after eating a meal,” says Lane. “This spike in glucose is even larger and longer-lasting if caffeine is present. So, it’s reasonable to say that caffeine and coffee seem to make diabetes symptoms worse.”
So what, then, is a Type 2 diabetic to do? Omit the soda and coffee, according to Lane. “In my opinion, people with diabetes should try quitting caffeine and see if this helps with their blood glucose control,” he says. “I suspect it will.”
Who can:
Other researchers are investigating the relationship between drinking coffee and the likelihood of developing new cases of Type 2 diabetes. A significant body of evidence—more than a dozen separate studies—has found that coffee drinking is inversely related to the risk of developing Type 2 diabetes. Otherwise put, the more coffee you drink, the lower your chances are of ever getting the disease.
Still, many scientists—Lane included—are hesitant to say that coffee really protects against diabetes. “Coffee drinking may just be an indicator of another health behavior, and this health behavior might be the real source of the reduced risk,” says Lane. For example, heavy coffee drinkers probably don’t drink a lot of sweetened sodas because they are too busy sipping lattes and espressos, he says. “And we know for a fact that drinking lots of sweetened sodas increases your risk of developing Type 2 diabetes.”
“We’re still in the middle of this,” assures Lane. “We’re still searching for the right answers.” But even with the science incomplete, healthy coffee drinkers still have a reason to rejoice. At worst, their daily cup [or two] of black brew is innocuous. At best, it will mysteriously safeguard against disease.
Moderation and Miscarriages
The harmful potential of drinking coffee during pregnancy lies in drinking upward of 300 milligrams of caffeine—or about three cups of coffee—per day. To be safe, Mark Klebanoff, a pregnancy epidemiologist at the National Institute of Child Health and Human Development, recommends that expectant mothers limit their coffee consumption to one or two cups a day or, even better, that they quit the java completely.
His recommendation, however, does not imply that the science has finally settled down: “This topic is virtually impossible to study [without causing some controversy],” says Klebanoff.
When researchers study the effects of caffeine doses below 300 milligrams, the results are even more is inconsistent, says Klebanoff. “Overall, the evidence for suggesting that caffeine causes miscarriages is really not very strong,” he adds.
Morning sickness is at the core of all this confusion, Klebanoff says.
“We have found that one of the earliest signs of a pregnancy is that you start getting nauseated,” he explains. “You develop strong food aversions, and a lot of smells make you very sick. One of the major side effects of all this nausea is that you just cannot look at a cup of coffee anymore.”
But feeling like you’re always about to hurl at this point in the pregnancy is actually quite healthy, according to Klebanoff. “When women don’t experience morning sickness, this could suggest that something is not right,” he says.
In fact, an increasing number of new studies have found that women are more likely to miscarry if they do not feel nauseated during early pregnancy. It is likely that these same women drink more coffee simply because they still have an appetite for it. In this scenario, Klebanoff points out, higher coffee consumption is the result—not the cause—of a miscarriage.
“We just do not know what the real story is,” he adds. But, given the situation’s worst-case scenario, and considering that quite a few studies have linked caffeine to miscarriage, why risk it, the scientist says: “Prudence should dictate. If you are a coffee drinker and you become pregnant, I suggest that you quit drinking coffee altogether or, at least, reduce your intake to one or two cups a day.”
Brewing Up Protection Against Parkinson’s disease
Oh, how far the little coffee bean has come … not 30 years ago, doctors blasted the caffeinated bean as possibly toxic and marginally safe. The good news, coffee drinkers, is that the medical community has since changed its tune. In fact, the latest science suggests that your morning cup of coffee just might help protect against Parkinson’s disease.
“The data is pretty strong,” says Alberto Ascherio, a professor of nutrition at Harvard University and one of the nation’s leading scientists in the study of caffeine’s effect on Parkinson’s. “So far, the research has consistently shown a link between a lower risk of getting [the disease] and a moderate consumption of caffeine.”
For instance: In a 30-year survey of Japanese-American men, scientists from Hawaii found that non-coffee drinkers faced double the risk of developing Parkinson’s when compared to men who drank just one to two small (4 ounce) cups of coffee a day. Even more, the non-coffee drinkers were at five times the risk of developing the disease relative to the study’s heaviest coffee drinkers (men who drank seven or more cups of coffee a day).
The link between coffee drinking and lower Parkinson’s-risk appears to be solid, but exactly why the relationship works is still a mystery, says Ascherio.
“In the animal model, when we give caffeine to mice, the caffeine seems to protect against [Parkinson’s] by binding to something called the a2a receptor,” he says. In the case of humans, however, scientists are still trying to confirm whether this same mechanism is responsible for reducing the risk of getting the disease.
“We don’t know the answer to that yet,” says Ascherio.
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