Whether it's an iced coffee on a summer morning, a hot cup before work or a warm latte on a snowy day, there is no doubt that Americans love coffee – or at least its caffeine.
We use it to wake up, stay focused and get work done.
But two age-old questions about the world's most widely used psychoactive substance linger: How much coffee is too much? And is it actually good for your health?
Studies around the world have attempted to address coffee's health effects to varying results. One study will say coffee is associated with a lower risk of cardiovascular disease, while a health professional will say it can lead to higher risk of the condition.
When it comes to a drink downed by roughly two-thirds of American adults each day, answers to such simple questions are surprisingly elusive.
First, go easy on cream and sugar
As long as you limit cream and sugar, coffee isn't fattening like other caffeine-based substances such as energy drinks and soda. The calorie content in a plain cup of brewed coffee is next to nothing, and there's no fat either.
But not everyone drinks their coffee black, as any Starbucks menu suggests.
Loading up a coffee with too much cream or sugar can drown out some of the positive health associations it provides.
“We know that sugar has adverse effects,” Penny Kris-Etherton, a nutrition professor at Penn State University, told the American Heart Association.
“Even if you add sugar and don’t exceed your calorie needs, you’re still negating some of the benefits because sugar is a negative food ingredient.”
Does coffee cause cancer?: California says those ominous warning signs about coffee being linked to cancer can be taken down
How much coffee is too much?
There's ongoing dissent in the health community about how much coffee one should drink.
Among recent studies, The American Journal of Clinical Nutrition concluded in March that six eight-ounce cups or more per day can increase risk of cardiovascular disease by 22%. The study examined nearly 350,000 individuals.
Similarly, a 2013 study by University of South Carolina researchers found men and women under the age of 55 who consume an average of more than 28 cups per week (four per day) were more closely associated with death over the course of the 32-year-long study.
What a typical home costs in your state: Can you guess which is the most expensive?
But other research has found that even extremely high coffee intake may be safe. One study partially funded by the British Heart Foundation said you can safely drink 25 cups of coffee per day. It should be noted, however, that the study examined only about 8,000 people around the United Kingdom.
Multiple studies have found that a daily coffee intake of four cups is a safe amount. Even federal dietary guidelines suggest three to five eight-ounce cups of coffee per day (providing up to 400 milligrams of caffeine) can be a part of a healthy diet.
Dr. Steven Nissen, Chief Academic Officer of the Heart and Vascular Institute at the Cleveland Clinic, told USA TODAY there isn't a specific daily limit that would apply to everyone, but drinking more than four to five cups provides for more caffeine than he would recommend.
"Keep in mind that the biological half-life of caffeine is seven to nine hours. So, if you have a bunch of coffee in the morning, it'll be gone by bedtime. But, if you drink it all day long and you really load up, you may have insomnia, which really is an issue," said Nissen.
Not all people react to caffeine in the same way, so if you are feeling some of the negative symptoms of the substance, like insomnia or anxiety, don't be afraid to scale back or cut off your coffee intake.
But is coffee good for you?
Many studies, like the ones cited above, suggest that up to four cups of coffee is a safe amount, but is it actually beneficial for you?
Several studies associate normal coffee consumption with health benefits, but they don't prove causation.
According to the previously mentioned AJCN study, people who don't drink coffee have a 11% higher chance of cardiovascular disease than those who consume one to two cups per day. The study found decaf drinkers had a 7% higher chance of developing cardiovascular disease as well.
A study from the National Institutes of Health published similar findings: those who drank at least three cups of coffee daily had a 10 percent lower risk of death. The review examined over 400,000 men and women ages 50 to 71.
Additionally, two studies in the Annals of Internal Medicine supported the idea that a few cups of coffee is linked to a longer life.
One study examining over 185,000 Americans reported an 18% decreased chance of death compared to non-drinkers. The other study, comprised of more than 520,000 people across Europe, also found that people who drink several cups per day had a lower risk of death than non-drinkers.
However, it's important to note that these studies are simply observing trends between coffee consumption and health; they don't determine if coffee actually leads to health benefits.
Along those lines, Nissen staunchly opposed the notion that coffee actively decreases risk for cardiovascular disease.
"I don't buy it for a moment," he said. "These are what are called observational studies, they're not optimized control trials. They're poor in quality. They're not reliable. I would not drink caffeine to lower your risk of heart disease."
Nissen views coffee as somewhat of a neutral substance – it won't actively benefit your health, but a safe amount of it is not necessarily bad for you either.
"My advice to patients is if you like coffee and you want to drink it, it's probably safe. Unless, of course, you have heart rhythm problems, where you can see some increased risk of palpitations," Nissen said.
"With that exception, I don't think there's any evidence for harm, but I don't think there's any evidence for benefit."
Specialty types of coffee, however, like French press coffee, boiled Scandinavian brew and espresso, possess a powerful cholesterol-booster and can raise cholesterol levels by 6 to 8 percent.
What about for children and teens?
Of course, caffeine is not limited to adults, and caffeine intake for those 18 and under should be more closely monitored, as you might expect.
The American Academy of Pediatrics suggests kids aged 12 to 18 limit caffeine use to 100 milligrams per day — about one cup of coffee, one to two cups of tea or two to three sodas.
Are you guilty of these? 3 spending habits that are ruining your chances at retirement
Though few and far between, there are nightmare stories involving teens and caffeine.
Davis Allen Cripe, a 16-year-old high schooler from South Carolina, died in 2017 from a caffeine overdose when he drank a large Diet Mountain Dew, a cafe latte from McDonald’s and an energy drink all within about two hours.
As for those 12 and under, there is no definitive amount that can be considered safe for all ages.
Keeping a close eye on the caffeine intake of younger ones can help prevent some of the negative side-effects, like anxiety, diarrhea and dehydration.
Follow Jay Cannon on Twitter: @JayTCannon
This article originally appeared on USA TODAY: Health benefits of coffee? How much to drink, and are there risks?