It’s part of the morning ritual, but is coffee good for you?

Some of us are very utilitarian about the drink while others perform elaborate rituals. Coffee is steeped into Western culture. Just the right amount can improve our mood; too much may make us feel anxious and jittery.

Caffeine is a psychoactive drug, and coffee is its biggest dietary source.Credit:iStock

Is coffee good for me?

Yes. In moderation, coffee seems to be good for most people – that's three to five cups, or up to 400 milligrams of caffeine.

"The evidence is pretty consistent that coffee is associated with a lower risk of mortality," said Erikka Loftfield, a research fellow at the National Cancer Institute in the US who has studied the beverage.

For years, coffee was believed to be a possible carcinogen, but the American 2015 Dietary Guidelines helped to change perception. For the first time, moderate coffee drinking was included as part of a healthy diet. When researchers controlled for lifestyle factors, like how many heavy coffee drinkers also smoked, the data tipped in coffee's favour.

A large 2017 review on coffee consumption and human health in the British Medical Journal also found that most of the time, coffee was associated with a benefit, rather than a harm. In examining more than 200 reviews of previous studies, the authors observed that moderate coffee drinkers had less cardiovascular disease, and premature death from all causes, including heart attacks and stroke, than those skipping the beverage.

Some of the strongest protective effects may be with Type 2 diabetes, Parkinson's disease and liver conditions.

In addition, experts say some of the strongest protective effects may be with Type 2 diabetes, Parkinson's disease and liver conditions such as cirrhosis, liver cancer and chronic liver disease. For example, having about five cups of coffee a day, instead of none, is correlated with a 30 per cent decreased risk of Type 2 diabetes, according to a meta-analysis of 30 studies.

The potential benefit from coffee might be from the polyphenols, which are plant compounds that have antioxidant properties, according to Dr Giuseppe Grosso, an assistant professor in human nutrition at University of Catania in Italy and the lead author of an umbrella review in the Annual Review of Nutrition.

However, coffee isn't for everyone. There are concerns about overconsumption. This is especially true for expectant mothers because the safety of caffeine during pregnancy is unclear. While the research into coffee's impact on health is ongoing, most of the work in this field is observational.

"We don't know for sure if coffee is the cause of the health benefits," said Jonathan Fallowfield, a professor at the University of Edinburgh and co-author of the British Medical Journal review."These findings could be due to other factors of behaviours present in coffee drinkers."

Does the way coffee is prepared matter?

Yes. Do you prefer a dark or light roast? Course grinding or fine? Arabica or robusta?

"All of these different aspects affect the taste but also affect the compounds within the coffees," said Neal Freedman, a senior investigator with the National Cancer Institute. "But it's not clear at all how these different levels of compounds may be related to health."

Roasting, for example, reduces the amount of chlorogenic acids, but other antioxidant compounds are formed. Espresso has the highest concentration of many compounds because it has less water than drip coffee.

A study in JAMA Internal Medicine examined the coffee habits of nearly 500,000 people in the U.K. and found that it didn't matter if they drank one cup or chain-drank eight — regular or decaf — or whether they were fast metabolisers of coffee or slow. They were linked to a lower risk of death from all causes, except with instant coffee, the evidence was weaker.

The way you prepare your cup of joe may influence your cholesterol levels, too. "The one coffee we know not suitable to be drinking is the boiled coffee," said Marilyn Cornelis, an assistant professor in preventive medicine at the Northwestern University Feinberg School of Medicine and co-author of the JAMA Internal Medicine study.

Examples of this include the plunge-happy French press, Scandinavian coffee, or Greek and Turkish coffee — the kind commonly consumed in the Middle East. (When poured, the unfiltered grounds settle on the tiny cup's bottom like sludge. To peek into the future, elders in the region have a tradition of reading the sediment of an overturned cup, like a crystal ball.)

The oil in boiled coffee has cafestol and kahweol, compounds called diterpenes. They are shown to raise LDL, the bad cholesterol, and slightly lower HDL, what's known as the good kind.

"If you filter the coffee, then it's no issue at all," said Rob van Dam, a professor at Saw Swee Hock School of Public Health at National University of Singapore. "For people with cholesterol issues, it's better to switch to other types of coffee." He's been studying coffee for two decades. (And, yes, he's had a lot of coffee in that time.)

However, other researchers say not to throw out the boiled coffee just yet. The clinical significance of such small increases in cholesterol may be questionable, given that it's not associated with an increase in cardiovascular deaths.

Many consumers have also swapped loose grounds for coffee pods. While there are environmental concerns with single-use pods, researchers believe them to hold the same benefits as, say, drip coffee. The latter applies to cold brew, too, but more research is needed.

Do all kinds of coffee have the same amount of caffeine?

No. Espresso has the highest concentration of caffeine, packing about 70 milligrams into a one-ounce shot but is consumed in less quantities. By comparison, a typical 12-ounce serving of drip coffee has 200 milligrams of caffeine, more than instant's 140. And, yes, brewed decaf has caffeine, too — 8 milligrams — which can add up.

When buying coffee, you never really know what you're going to get. At one Florida coffee house, over a six-day period, the same 16-ounce breakfast blend fluctuated from 259 milligrams all the way up to 564 — which goes beyond federal recommendations.

But for some of us, knowing how much caffeine is in our coffee can be especially important. You've probably noticed it before. How a friend can pound quadruple espresso shots at 10 p.m. and sleep afterward, while you can't have any past noon or you'll be watching Seinfeld reruns until dawn. Some of us have a polymorphism, a genetic variant that slows our metabolism for caffeine. It's these individuals that Grosso recommends limit their refills. "They take a coffee, and then they have the second and the third, and they still have the caffeine of the first," he said.

Is coffee addictive?

Evidence suggests there can be a reliance on the drink, and tolerance builds over time. Withdrawal symptoms include a headache, fatigue, irritability, difficulty concentrating and depressed mood.

Indeed, caffeine is a psychoactive drug, and coffee is its biggest dietary source. About a half-hour after sipping a cup of joe, the caffeine kicks in and is quickly absorbed. Blood vessels constrict. Blood pressure increases. A moderate amount of caffeine can wake you up, boost your mood, energy, alertness, concentration and even athletic performance. On average, it takes four to six hours to metabolise half the caffeine.

For those knocking back more than 400 milligrams of caffeine a day, there's not enough evidence to assess the safety, according to the Dietary Guidelines. Higher doses can lead to caffeine intoxication, with its shakiness, nervousness and irregular heartbeat. Caffeine is also linked with delaying the time it takes for you fall asleep, how long you stay there and the reported quality of that shut eye.

"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," said Mary Sweeney, an assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.

Cutting down coffee may help with gastroesophageal reflux, too. A new study found that women drinking caffeinated beverages – coffee, tea or soda – were associated with a small but increased risk of symptoms, like heartburn. The study's authors predicted fewer symptoms when substituting two servings of the drinks with water.

Current available research hasn't determined what amount of caffeine can be safely consumed during pregnancy, according to the American College of Obstetricians and Gynecologists. Caffeine does cross the placenta so some doctors may recommend pregnant women stay below 200 milligrams of coffee daily.

Extremely high doses of caffeine can be fatal. But researchers say that's more likely to occur accidentally with caffeine powder or pills. "You don't see a lot of people going into the emergency room because they accidentally drank too much coffee," said van Dam.

Should I start pounding down more coffee?

It depends on your goals in life.

If you are enjoying the drink in moderation, doctors say continue onward and salvor those sips. And for those patients with a sensitivity to the beverage, Dr. Sophie Balzora, a gastroenterologist, weighs the benefits and risks very carefully. The clinical associate professor of medicine at NYU School of Medicine understands its cultural significance and knows to tread lightly. As she put it: "Robbing people of their coffee seems cruel."

The New York Times

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