Coffee: Health Benefits, Brewing Methods, and Busted Myths
Confused about coffee? Some people still say it’s bad for you, but is it? Or are their opinions outdated?
In this article, I’ll separate myth from fact, and share a little history on how coffee came to be such an incredibly popular beverage.
- The Birth of the “Coffee is Bad for You” Myth
- Where the First Coffee Came From
- Coffee Brewing Methods
- Coffee Health Benefits
- Coffee and Physical Performance
- Coffee and Weight Management
- Coffee, Insulin Resistance and Diabetes
- Coffee and Cardiovascular Disease
- Coffee and Cancer
- Coffee and Liver Health
- Coffee, Cognitive Function, and the Nervous System
- Coffee and Bone Health
- Coffee and Gut Health
- Final Sips
The Birth of the “Coffee is Bad for You” Myth
The year was 1992. In sports, the Blue Jays won the World Series, the Redskins won the Super Bowl, and Andre Agassi and Steffi Graf won at Wimbledon.
In entertainment, Tom Hanks yelled, “There’s no crying in baseball!” while Jack Nicholson scorned, “You can’t handle the truth!”
And in the world of coffee, health advocates warned the public of the problems it can cause. As Dr. Tony Chou said,
The recent decline in caffeine and coffee consumption reflects the widespread awareness of the debate about possible adverse effects of caffeine on health.Dr. Tony Chou, Western Journal of Medicine, 1992
Fortunately, Starbuck’s didn’t listen. By 1992, they’d grown to 165 coffee shops and went public on the stock exchange. That same year, John Sylvan and Peter Dragone founded Keurig.
1992 was a long time ago. Like those who still want Zubaz to stay in fashion, some people still hold onto the beliefs about coffee that were common back then.
Times marches on. Research accumulates. Thinking evolves. Beliefs change.
Coffee or Die
Coincidentally, I’m wearing a t-shirt that says, “Coffee or Die” as I write this article. My wife and I love coffee.
We appreciate the delightful aroma, the unique and flavorful taste (well, at least most dark roasts; not so much the light roasts or medium roasts), and even the warmth of the cup as we begin each day.
I don’t love it enough to die for it, though. And if I believed it was detrimental to my health, I’d give it up right away.
I started writing this article to find out what was bad about coffee and to see if there are reasons to stop drinking it.
However, the more papers I read and reviewed (many of which you’ll find in the references section at the end), the more I realized that coffee is seriously good for you.
Where the First Coffee Came From
According to the National Coffee Association, coffee originated in Ethiopia.
The legend of its discovery revolves around a goat herder named Kaldi.
After eating the cherries from a particular tree, Kaldi noticed his goats weren’t going to sleep when they were supposed to. Instead, they danced and goofed around, like little kids (pun intended).
He shared his findings with his dad, and they spread the word around Ethiopia.
Sometime between 865-925 AD, a physician named Rhazes became the first to write of coffee in print.
By the 1400s, people made an early version of the coffee we drink today. Arab Surfi monks drank it to stay awake for midnight prayers, wealthy citizens added coffee rooms in their homes, and coffeehouses came to being.
Muslim pilgrims brought coffee to Persia, Egypt, Syria, and Turkey, and the coffee trade began.
In Turkey, coffee became so important that if a husband could not provide enough coffee for his wife, it was grounds for divorce.
When coffee was introduced to Europeans in the 1600s, some called it a “bitter invention of Satan.” Pope Clement VIII gave it papal approval, easing the concern that it was evil.
In the new world, Americans drank more tea than coffee until 1773. That’s when King George III taxed tea so much that it led to the Boston Tea Party. Americans have been drinking more coffee than tea ever since.
Each year, people drink more than 2 billion cups of coffee. Imagine if Kaldi’s goats had never chewed on the cherries!
Coffee Brewing Methods
Coffee contains more than 1000 chemicals. The most abundant and studied are caffeine, diterpenes, and polyphenols.
The type of bean, the way it is grown, cultivated, harvested, dried, and roasted all affect which chemicals are left in the beans before you brew them.
The most popular method of brewing is different throughout the world, which can affect the chemical compounds that make it into your cup.
Most automatic coffee makers and many pour overs use a filter. Filters remove the oils as the coffee brews.
Scandinavian boiled, French press, Turkish/Greek, and espressos are considered “unfiltered” brewing methods.
Your latte, cappuccino, macchiato, Americano, and other sweet coffee drinks likely have a base of espresso as well, so they are “technically” be considered unfiltered coffee.
Just to make sure I say it, the health benefits I discuss in this article are related to plain, black coffee. Please don’t expect the same kind of health benefits from “coffee drinks” that include cream, sugar, syrup, and candy.
Coffee Health Benefits
Over the past 500 years, coffee has been treated as medicine, poison, and everything in between.
Whether it was a political thing, or because the French just wanted to be different, they tried to dissuade people from drinking caffe.
French doctors, threatened by the medicinal claims made for coffee, went on the counterattack in Marseilles in 1679: “We note with horror that this beverage . . . has tended almost completely to disaccustom people from the enjoyment of wine.” Then, in a fine burst of pseudoscience, one young physician blasted coffee, asserting that it “dried up the cerebrospinal fluid and caused convolutions . . . the upshot being general exhaustion, paralysis, and impotence.” Six years later, however, Philippe Sylvestre Dufour, another French physician, wrote a book strongly defending coffee, and by 1696 one Paris doctor was prescribing coffee enemas to “sweeten” the lower bowel and freshen the complexion.Mark Pendergrast, Uncommon Grounds: The History of Coffee and How it Transformed Our World
This back and forth of coffee being “good” or “bad” has gone on for centuries. Even over the past 60 years, there’s been plenty of controversy about its health benefits or detriments.
Like the taste of poorly brewed java, public opinion about coffee turned bitter in the mid-1960s.
Researchers and healthcare practitioners looked for connections between Americans’ eating habits and the increasing rates of heart disease and other health problems. As with dietary fat, coffee became guilty by association.
Americans drank a lot of java, and rates of heart disease and other illnesses were increasing, so coffee took the blame, and it was deemed unhealthy for the next few decades.
I showed you an excerpt from Dr. Tony Chou’s paper, published in 1992, at the beginning of this article. It was a good example of the assumption about coffee at the time.
Chou continued in the paper, explaining how coffee was detrimental to the gastrointestinal tract, hormone and neurotransmitter production, cardiovascular system, brain, and cancer development. He even connected it to schizophrenia.
I don’t blame Chou. He based his opinions on the limited research he had available.
Contrast that with this statement from a more recently published paper:
In light of current knowledge, habitual moderate coffee intake may help prevent several chronic diseases, including type 2 diabetes mellitus, coronary heart disease, and Parkinson’s disease.Regina Wierzejska
Unfortunately, Chou’s sentiments are still repeated today, even though they’ve been refuted with better quality and larger volumes of research.
Coffee and Physical Performance
Without question, caffeine enhances exercise performance. It improves reaction time, fat metabolism, stamina, strength, power, and multiple other measures of performance.
Coffee has a similar effect — although it’s difficult to consume the high amounts of caffeine found in energy drinks, through normal coffee. You’d end up drinking a pitcher, and it probably wouldn’t sit well in your stomach during your workout or event.
That said, you could easily drink a couple cups prior to a workout.
One other physical performance question that often comes up is, “Doesn’t coffee make you dehydrated?” Oh, how I wish this myth would go away.
Pure caffeine is a mild diuretic. You need a dose of about 500 mg without drinking any fluids to create a diuretic effect. A cup of joe contains way more water than you lose from the caffeine. Feel free to count it in your total water intake for the day.
Coffee and Weight Management
People often tell me, with enthusiasm, that they’ve given up coffee as part of their new diet. If by “coffee,” they mean their 500-calorie milkshake, that’s great! However, if they’re referring to black coffee, it’s not necessary, or even helpful.
Coffee reduces appetite, especially in overweight or obese people.
A single cup doesn’t have much of an effect on appetite or energy intake, but in overweight or obese individuals, moderate consumption (two to four cups) markedly reduces food intake later in the day.
Theoretically, the caffeine in coffee could raise metabolic rate, but the effect is minor. According to research, caffeine increases metabolic rate by 0.1 calorie per milligram.
Four cups of coffee, which would contain about 320 milligrams of caffeine, would boost metabolic rate by 32 calories per day. The breath mint you use after your coffee will probably offset that insignificant increase in metabolic rate.
Coffee, Insulin Resistance and Diabetes
High levels of coffee consumption reduce the risk of type 2 diabetes, at least according to population-based data.
Compared with no coffee consumption, consumption of six cups per day of coffee was associated with a 33% lower risk of type 2 diabetes.Ming Ding, et al.
What makes this so interesting is that caffeine itself tends to reduce insulin sensitivity, so other chemicals must enhance blood sugar management and offset the effects of the caffeine.
Chlorogenic acid could be one of those compounds. It reduces glucose absorption, oxidative stress, and liver glucose secretion. Caffeine also reduces glucose release by the liver as it causes the body to use fat for fuel in place of glucose.
Other compounds found in java that support blood sugar control include lignans, quinines, and trigonelline.
Coffee and Cardiovascular Disease
A recent meta-analysis by Ding et al., based on more than one million people, showed that moderate coffee consumption — defined as three to five cups per day — reduced the risk of cardiovascular disease. Higher intake did not seem to not affect risk one way or the other.
Interestingly, heavy consumption and cigarette smoking often go hand in hand, so earlier research that connected heavy coffee drinkers to cardiovascular disease identified smokers.
Those who are heavy coffee drinkers and non-smokers do not have an increased risk of cardiovascular disease.
You might wonder what effect decaf has. The number of people who regularly drink decaffeinated coffee is so small that an effect on cardiovascular disease cannot be determined.
Even though the research on cardiovascular disease is positive, I do need to mention two potential issues.
Cafestol and kahweol, diterpenes found in the oil of coffee beans, can raise cholesterol levels and triglyceride levels.
I usually skip over references to cholesterol levels, since cholesterol levels have little, if any, direct impact on cardiovascular disease. However, since the diterpenes could increase triglyceride levels, it’s something to be aware of.
Reducing carbohydrates from your diet, especially sugar, will do much more to lower triglyceride levels than eliminating coffee. But for the sake of being complete on this topic, I did want to mention it.
Filters remove most of the diterpenes. So, if you drink mainly filtered coffee, the diterpenes are not a concern.
Elevated blood pressure and heart rate are also a concern for those with heart disease. Pure caffeine raises both. However, chlorogenic acid, which is a polyphenol, lowers blood pressure. This could be why coffee, which contains caffeine and theoretically could worsen cardiovascular disease, is cardioprotective.
Coffee and Cancer
Studies from decades ago suggested that coffee could increase the risk of cancer.
In 1991, the International Agency for Research on Cancer (IRAC) claimed it was “possibly carcinogenic to humans.”
Coffee roasting creates a potentially carcinogenic compound called acrylamide. One brewed cup contains about 0.45 µg. However, research in humans has not shown any connection between acrylamide and the development of cancer.
Unfortunately, a statement like the IRAC’s gets stuck in people’s minds, even after it’s been disproved.
Research since then refutes the idea that coffee is carcinogenic or contributes to cancer development. In fact, heavy coffee consumption can lessen the risk of certain cancers such as colorectal, endometrial, breast, liver, prostate, and bladder cancers.
A meta-analysis of patients with gastric cancer showed that moderate consumption decreased risk, but more than six cups per day slightly increased it. The numbers of people drinking six cups of coffee per day in the research was small enough that researchers emphasized caution in suggesting that six cups per day increased risk. It wasn’t possible to exclude smokers from the six-plus cups per day group either, so it’s possible that smoking was the problem, not the coffee.
Caffeinated coffee, but not decaf, also seems to protect against malignant melanoma.
Coffee is rich in antioxidants and is America’s top dietary source of them. Antioxidants combat free radicals, which are thought to cause cancer. So, it makes sense that coffee would help reduce the risk of the cancers listed above.
Coffee and Liver Health
The liver is the principal organs of detoxification. With more than 1000 chemicals in coffee, the liver is heavily involved in the metabolism of coffee.
To check your liver health, your doctor will include Alanine transaminase (ALT) in standard lab testing. ALT is a liver enzyme that increases in the blood when your liver is injured. Coffee drinkers have lower levels of ALT, which suggests it is protective for the liver.
Cafestol and kahweol, which I mentioned in the section on cardiovascular disease, support liver detoxification. Again, you only get these diterpenes when you drink unfiltered coffee.
In general, coffee seems to protect the liver from cancer, cirrhosis, fibrosis, and fatty liver disease.
Coffee, Cognitive Function, and the Nervous System
Caffeine is a nervous system stimulant. You might expect it to be detrimental to the brain and the rest of the nervous system, but it’s quite the opposite.
Caffeine itself has been shown to protect the brain from Alzheimer’s development in animal studies. It may also reduce nervous system inflammation.
Eskelinen et al. reported a 65% risk reduction for late-life dementia and AD (Alzheimer’s Disease) among drinkers of three to five cups of coffee per day during their middle life, compared with nondrinkers.Barbara Shukitt-Hale, et al.
Heavy coffee drinkers are also less likely to develop multiple sclerosis.
Caffeine improves vigilance and enhances feelings of well-being and energy. It modulates the release of the neurotransmitters acetylcholine and serotonin.
So, it’s little surprise that rates of depression decrease as coffee consumption increases, at least in women.
As another word of caution, a small percentage of people are hypersensitive to caffeine and should limit their intake. Also, if you need coffee just to survive the day, you might consider getting more sleep and modifying other lifestyle factors.
Coffee and Bone Health
Because caffeine may interfere with calcium metabolism, coffee is sometimes believed to lead to fractures and reduced bone health.
However, research shows that coffee does not negatively affect bone health in humans.
Hip fractures are common among older adults with reduced bone density, and frequency of hip fractures is often how researchers identify nutrition connections to bone health. Coffee consumption does not increase the risk of hip fractures, suggesting that it does not negatively affect bone metabolism in humans.
I did come across a study that showed daily coffee consumption by rats negatively affected tissue repair after their incisor teeth were removed. At this point, I would just recommend you not give a pet rat coffee to drink. I can’t say anything related to humans.
Coffee and Gut Health
People are sometimes cautioned against coffee consumption because of its acidic nature, based on speculation that it could worsen stomach problems.
However, research shows that coffee does not seem to contribute to gastric ulcers, duodenal ulcers, reflux esophagitis, or non-erosive reflux disease.
Coffee may also positively influence the growth of good bacteria in the gut. Just don’t put your probiotics in a hot cup of coffee to double-up on this benefit. You might ruin the taste of the coffee, and kill the bacteria with the heat of the liquid.
I hope I’ve given you plenty to sip on. As with every nutrition topic, there are always outliers. Some people might not do well with coffee, just as a small percentage might not do well on a low-carbohydrate diet.
I began this journey to discover whether coffee was good for me or not, and I’ve been pleasantly surprised by what I’ve learned. I hope you are too.
You’re probably due for another cup of coffee by now, or you need to warm yours up. Let me give you just a few more thoughts to consider.
Not only does coffee seem to reduce the risk of many diseases, it also reduces the risk of death in general.
Actually, to be more accurate, it reduces the risk of all-cause mortality. I mean, coffee won’t help you live forever, but it does seem to reduce the chance you’ll die prematurely from disease or accidents.
Long-term studies show coffee may increase glutathione levels, the body’s chief antioxidant, as well as reduce DNA damage by reducing oxidative stress.
Almost any time I discuss coffee with health and fitness enthusiasts, they bring up the question of whether to drink organic or not. I’m a fan of organic whenever possible, but it does increase the price, especially with coffee.
Most research on coffee is based on conventional coffee. If pesticides made their way into your brewed cup of joe, I believe we’d see more health problems than benefits.
Based on research, the pesticides are either burned off or degraded during the roasting period as well, which pretty much eliminates them from your brewed coffee.
Buy organic if you can. I’ll still drink it if it isn’t organic, though.
I have one last thing to share. Do you remember the statement by the IRAC in 1991, which I shared in the “Coffee and Cancer” section? Check out this quote from July of 2017:
We found that higher coffee consumption was associated with a lower risk of death from any cause, and specifically for circulatory diseases, and digestive diseases.Dr Marc Gunter, International Agency for Research on Cancer (IARC)
Alright, my cup is empty, so it’s time to get a refill.