Sept. 10 (UPI) -- Americans drink an average of three cups of coffee a day -- in the morning as a wake-up jolt, during the afternoon for a workday treat and at night for energy to pursue activities before going to bed.
Studies have shown the ingredients from the roasted bean can increase mental alertness, memory, stamina and concentration. But they also can heighten anxiety and stress and cause stomach problems in some people.
Studies have shown potential health benefits of drinking coffee to prevent diseases -- but also suggested the risk of certain conditions, including cancer.
Scrutiny has intensified recently as a California state judge ruled that coffee companies must use labels to warn customers that the carcinogen acrylamide is created during the roasting process.
Does all of this amount to a hill of beans?
Few serious risks
The Institute for Scientific Information on Coffee, a not-for-profit organization, was founded in 1990 by six major European coffee companies to study and disclose science related to coffee and health.
"Scientific studies, published in peer-review journals, demonstrate that moderate coffee drinking is perfectly safe for human health and may confer some health benefits," Roger Cook, the science manager for the institute, told UPI. "This is based on published science and not on my individual thoughts."
Recent studies seem to alternate between coffee's positive and negative effects, decades of research has shown relatively few serious health risks, including any strong link to cancer. But the concern remains because coffee is such a widely consumed beverage.
More than half of Americans over 18 drink coffee every day, representing more than 150 million daily drinkers, according to the National Coffee Association and The Specialty Coffee Association of America. Some 30 million of them drink specialty coffee beverages daily, including lattes, espressos, cafe mocha, cappuccinos and frozen/iced coffee beverages.
Sixty-five percent of all coffee is consumed during breakfast hours, 30 percent between meals and the remaining 5 percent with other meals.
The $18 billion U.S. coffee market includes beverages sold at more than 50,000 coffee shops, including Starbucks. In addition, the United States exports around $4 billion of coffee each year.
A long-time focus of research
For centuries, studies focused on medical benefits and dangers associated with the proper amount to consume, whether it is habit forming and caffeine levels.
In the 18th century, King Gustav III of Sweden conducted an experiment on two people to see whether tea or coffee kills faster. They both far outlived the king and the researchers conducting the experiment.
"Coffee is much more than just caffeine," Dr. Robert Shmerling, the clinical chief of rheumatology at Beth Israel Deaconess Medical Center in Massachusetts, told UPI. "It is a complex beverage with complex effects on the body. And, of course, there are many types of coffee that vary with how it's brewed, how strong it is, how much caffeine it contains and so on -- so the effects of different types of coffee vary."
On the positive side, he cited the antioxidant and anti-inflammatory effects, as well as improved insulin and glucose metabolism and increased neuroprotective effects, including alertness, concentration and possible cognitive function. These would be linked to a reduced risk of cardiovascular disease, type 2 diabetes, Parkinson's disease, uterine and liver cancer, cirrhosis and gout.
On the other extreme, he said studies have linked coffee to increased risk of bladder and pancreatic cancer, esophageal cancer and cardiovascular disease.
Confusing study results
In March, a study conducted in Brazil of more than 4,000 people found those who consume more than three cups of java a day might lower their risk of clogged arteries. Their coffee-drinking habits were correlated with coronary artery calcium, or CAC, readings.
But a 2006 study also found that found the risk of heart attack increased fourfold when they drank coffee -- which can make the plethora of study results somewhat confusing.
"People at high risk for a heart attack who are occasional or regular coffee drinkers might consider quitting coffee altogether," says researcher Ana Baylin, a research associate at Brown University School of Medicine in Providence, R.I., who studied 503 cases of non-fatal myocardial infarction in Costa Rica.
Some studies have found that two or more cups of coffee a day can increase the risk of heart disease in people with a specific and fairly common genetic mutation that slows the breakdown of caffeine in the body. So, levels of consumption can become a factor.
"It's likely that there is a threshold for coffee -- as for most good things -- some is good but more is not always better," Shmerling said. "At moderate levels of consumption -- 1 to 3 cups per day -- a number of health benefits are observed, including longer life, and in a recent study, even those drinking 8 or more cups/day saw benefits.
"But, since relatively few people drink well above 8 cups per day, we know less about whether there's a point of diminishing return. High consumption may cause unacceptable side effects -- palpitations, racing heart -- or frequent urination from all the fluids consumed."
Does coffee cause cancer?
In the last few years, the potential effects of carcinogens in coffee also have been debated.
Cook says, however, that there is no evidence that coffee increases risk for cancer. This was confirmed by the International Agency for Research on Cancer in 2016, which concluded the chemical and coffee consumption are not linked to medical problems.
But that's not the way Los Angeles County Superior Court Judge Elihu M. Berle sees it. Ruling in a lawsuit against coffee producers, distributors and retailers brought by a civic group that fights toxins, Berle found that the coffee companies failed to prove the level of acrylamide in coffee was not a significant risk. Berle ruled that companies selling coffee must tell their customers of the potential implications of exposure.
The nonprofit Council for Education and Research on Toxics, which filed the suit, based their claim on a state law, Proposition 65, which requires any food or drink that contains a substance found to cause cancer in animals to include information on labels or in places where it is sold. The defendants in the lawsuit, which was filed in 2010, included Nestle and Starbucks.
"Acrylamide, a substance found in a number of foods, is formed during the roasting of coffee beans in levels far below what was found to cause cancer in animals; thus far, acrylamide in coffee has not been linked to human cancers among coffee drinkers," Shmerling said.
A state agency in California agrees. The Office of Environmental Health Hazard Assessment has proposed updating the state's regulations after a hearing.
The U.S. Food & Drug Administration, which ensures that food is safe and truthfully labeled, said it was "deeply concerned" about the court ruling and sent a letter to the state agency voicing support for the exemption of coffee.
"Acrylamide can form in many foods during high-temperature cooking, such as frying, roasting and baking," the FDA said in a news release last week. "Acrylamide in food forms from sugars and an amino acid that are naturally present in food. It doesn't come from food packaging or the environment. In coffee, acrylamide forms during the roasting of coffee beans."
In 2016, the FDA posted a document to help growers, manufacturers and food service operators lower the amount of acrylamide in foods associated with higher levels of the chemical.
The IARC, which is part of the World Health Organization of the United Nations, listed it as a possible carcinogen in 2015 because of its link to cancer in rodents. But one year later it rescinded the warning after it asked 23 researchers to review more than 1,000 studies in humans and animals on consumption of coffee, finding "inadequate evidence" that drinking coffee is carcinogenic.
'Keep an open mind'
"I'm not very concerned and I don't think others should be," Shmerling said. "But it's a good idea to keep an open mind and look to the research for guidance in this regard. Compared to other known carcinogens, such as smoking, I would be less concerned."
Shmerling suggests consumers keep an eye on headlines suggesting the good or bad health effects of coffee, and carefully evaluate whether the headlines are based on well-conducted, randomized controlled trials.
And while research does not say what direction coffee drinkers should go in -- drink way more or way less for some type of health benefit -- Shmerling said people should decide for themselves if they want to drink coffee, though he issued a soft warning.
"Cutting out coffee from your routine may be accompanied by coffee cravings, headache, physical and mental sluggishness and irritability, but these tend to improve rather quickly over a short time." Shmerling said. "And they can be largely avoided by gradually reducing coffee over a number of days or weeks."