Coffee: the Good & the Bad

By Stephen T. Sinatra, M.D., F.A.C.C., F.A.C.N., C.N.S., C.B.T.

Coffee. If you’re like most people, it’s more than just a beverage. It’s a way of life, and one you probably can’t imagine changing.

According to the National Coffee Association’s 2020 survey of American coffee drinking habits, 70% of Americans consume this beverage every week—and a whopping 62% every day. The average coffee drinker enjoys just over three cups a day. Overall, consumption is up by 5% across the nation since 2015.

That’s a lotta java!

While I’m not as big of a coffee drinker as I used to be, I can relate. Without the caffeine boost in coffee to pick me up and keep me focused, I probably wouldn’t have survived all those long shifts in the cardiac ward as a young doctor.

As beneficial as caffeine can be if you need a quick jolt of energy, most of the confusion over whether coffee is good or bad for our health has to do with its caffeine content.

The Caffeine Conundrum

Coffee is one of the largest sources of caffeine, a natural yet highly addictive stimulant. Research has shown it doesn’t take much caffeine to get hooked—and coming off of it can cause some pretty powerful withdrawal symptoms.

Anyone who’s tried to give up coffee (or simply skipped their usual morning cup) knows all too well the symptoms of caffeine withdrawal: headache, irritability, lethargy, anxiety, lack of concentration, and even heart rhythm abnormalities like palpitations.

The enzyme CYP1A2 is mainly responsible for how we metabolize caffeine. In some people, this enzyme works pretty efficiently—those are the folks who are unfazed by caffeine’s effects, rarely experience serious withdrawals, and can drink coffee or other caffeinated beverages late into the night and still sleep like a baby.

In less efficient metabolizers, caffeine has a much stronger effect. If you’re one of those people, you should be careful about when and how much caffeine or coffee you drink—unless your goal is to boost your energy or stay awake.

Caffeine can also have a negative effect on arrhythmia, or irregular heartbeat. While studies continue to find no connection between caffeine and risk of arrhythmia like atrial fibrillation, my personal and clinical experience says otherwise. When I was actively seeing patients, I saw over and over that caffeine can be problematic for people with poor heart rate variability or whose hearts are compromised by disease or a previous heart attack. I advised these patients to avoid caffeine altogether, whether in coffee, tea, or chocolate.

Since caffeine is a stimulant, it turns on the sympathetic nervous system and initiates a stress response. This causes an adrenaline release that instantly requires that the heart beat harder and faster. If your heart function is already less than ideal, this can be a recipe for trouble. On the other hand, if your heart is healthy, caffeine shouldn’t be problematic.

Along with its stimulant effects, caffeine is a diuretic. As such, it carries some of the same risks as more potent diuretics, including the loss of vital water-soluble nutrients like magnesium, potassium, and B vitamins. Granted, this risk is relatively small with coffee—but it’s important for patients with conditions like heart disease to be aware of it, since small deficiencies in nutrients like magnesium can have a big impact on heart function.

Health Benefits of Coffee

Caffeine concerns aside, coffee does have some pretty significant health benefits. Coffee’s benefits are largely thought to be tied to its high concentration of polyphenols—antioxidant nutrients that help offset inflammation and protect against disease throughout the body. (Polyphenols are found in all plant foods and also happen to be part of the magic in my favorite health-promoting food, olive oil.)

Some of the strongest benefits of coffee appear to occur in the cardiovascular and neurological systems. Let’s take a look at the research. 

Coffee and Heart Disease

According to two large meta-analyses—one including more than 400,000 cohort subjects, and the other more than 1 million—there is no association between drinking coffee and the long-term risk of developing heart disease. In fact, the first study found that moderate coffee consumption reduced this risk in women, and the second found that 3–5 cups of coffee a day reduced risk across the board.

This makes perfect sense when you account for the beneficial effect coffee has on some of the biggest risk factors for heart disease, like type 2 diabetes and obesity. Reduce or eliminate issues like diabetes, and there’s less wear and tear on your heart and arteries. In fact, a meta-analysis of 30 studies, including 1,185,210 participants, found that the risk of type 2 diabetes decreased by 6% for each cup-per-day increase in coffee consumption. And results were the same for caffeinated and decaf.

There’s also one recent study that suggests coffee may help protect against arterial calcification—but only in nonsmokers. (Another great reason to quit!)

Coffee and Cardiac Death

If coffee drinkers are less likely to develop heart disease, you’d expect them to be less likely to die of cardiovascular events, too—and that’s exactly what the research shows. However, coffee drinkers aren’t just less likely to die from heart attacks, strokes, and heart failure. They’re also less likely to die from cancer, Alzheimer’s disease, and other causes.

Where cardiovascular events are concerned, though, The Nurse’s Health Study, a long-running look at more than 80,000 women, found a specific reduction in stroke risk among women who drank 2–3 cups per week (a 19 percent reduction) and who drank 4 or more cups per week (a 20 percent reduction). Another long-running study, EPIC (European Prospective Investigation into Cancer and Nutrition) found similar outcomes after following over a half million people for an average of 16 years. Additional research has found similar results regardless of gender.

The drop in risk may be due in part to a finding by Greek researchers that coffee improves endothelial function. When the endothelial cells lining your arteries are healthy, blood flows more easily, the heart doesn’t have to work as hard, and you’re less likely to develop atherosclerosis.

Another possibility is something the EPIC researchers uncovered… Women in their study were also likely to have lower levels of lipoprotein(a), CRP, and HbA1c. These factors are all associated with artery-damaging inflammation. Both possibilities are certainly worthy of further research.

Coffee and Blood Pressure

We used to think that long-term caffeine consumption could increase the probability of developing high blood pressure, but multiple studies have proven that idea to be untrue. Some even suggest the opposite—that caffeine may help protect against high blood pressure.

But what if you already have high blood pressure? The science here is mixed. An Italian study that followed more than 1,200 adults, ages 18–45, with untreated mild hypertension concluded that heavy coffee drinkers (4 or more cups a day) had four times greater risk of having a cardiac event, and moderate drinkers (1–3 cups) a three times greater risk. However, subsequent research has stated that coffee consumption is probably safe—though it should be done cautiously.

My advice is to listen to your body. If you have a cup of coffee and notice that your blood pressure goes up, it’s probably best if you steer clear. The same is true if you have trouble controlling your blood pressure even when you’re not drinking coffee. But if your blood pressure is normal and stays that way even with a jolt of caffeine, then enjoy your java!

Coffee and Alzheimer’s / Cognitive Decline

Research has also found that coffee may protect against cognitive impairment, Alzheimer’s disease, and Parkinson’s disease.

A study of 1,445 people found that cognitively normal people who drank 1–2 cups of coffee daily had a lower incidence of mild cognitive decline compared to those who never or rarely drank it. More than that, though, had the opposite effect. So, if you’re worried about cognition as you get older, moderation may be the key with coffee consumption.

A more recent study examined coffee’s effect on the development of Alzheimer’s disease—more specifically, deposits of beta-amyloid plaques, a telltale sign of Alzheimer’s. The researchers discovered that drinking at least two cups a day was associated with lower plaque deposition compared to intake of less than two cups per day. They wrote that, “The findings suggest that higher lifetime coffee intake may contribute to lowering the risk of [Alzheimer’s disease] or related cognitive decline by reducing pathological cerebral amyloid deposition.”

Coffee and Parkinson’s Disease

Likewise, a growing body of research—including a 30-year JAMA study—has confirmed the protective effect of coffee (and in particular caffeine) against Parkinson’s disease.

Other research suggests that caffeine and the fatty acid in coffee EHT work together to defend against Parkinson’s.

Coffee and Depression

A meta-analysis that examined 12 studies (totaling 346,913 people) showed that those with greater intake of coffee were less likely to suffer from depression.

Which Coffees are the Healthiest?

The type of coffee you drink plays a role in how good the coffee you’re drinking is for you. According to a 2017 study, polyphenol content of coffee varies based on the roasting process and origin of the beans. Noting that high temperatures can reduce the amount of polyphenols in a given food, the researchers found that “longer roasting periods caused a significant decline in polyphenol compound levels in the coffee beans.”

Paradoxically, even though natural polyphenol levels decrease during roasting, roasting coffee creates changes the chemical structure of coffee in a way that actually increase antioxidant activity. So coffee appears to have a sweet spot, and the research indicates that light- or medium roasted coffee offers the most nutritional benefit.

The researchers also found that where the beans were grown impacted polyphenol content, though to a lesser degree than the amount of time they were roasted. Beans from Ethiopia and India had slightly more polyphenols than beans from Columbia and Brazil.

Through a 2019 study, other researchers also found that organic coffee beans had a slightly greater phenolic acid and flavonoid content than conventionally produced coffee. More importantly, the longer the period of storage of the beans, the greater the loss of polyphenol content. So if you’re drinking a coffee from beans that have been sitting on a shelf for a year or more, you’re not going to get the same polyphenols from a fresher coffee.

What does all this mean for you when buying coffee? Choose light or even medium roast coffee, preferably organic, and check the date on the bag.  The longer the beans have been roasted, the darker their color – so opt for lighter colored, milder beans.

The Sinatra Solution: Everything in Moderation

Essentially, the question of whether coffee is good or bad for you boils down to weighing the negative effects of caffeine against the protective benefits of coffee.

In my opinion, there’s nothing wrong with 1, 2 or even 3 cups of coffee a day if your heartbeat and blood pressure are not adversely affected. The majority of the research supports this, too. (Just don’t overdo it with sugar or artificial sweeteners, which can offset all of coffee’s benefits.)

I don’t recommend too much more than that, however, since there may be some additional risk for anyone with diagnosed cardiovascular disease or a history of heart attack. The protective benefits of coffee are certainly something you want to take advantage of, but that desire needs to be weighed carefully with the potential downsides.

As the polyphenol benefits that coffee offers are a certainly a big win, one possible solution for those who have caffeine sensitivities is to drink decaffeinated coffee. While decaf is not completely caffeine free, it’s a viable way of reducing possible undesirable effects of higher caffeine consumption. And the nutritional value of decaf coffee may be on par with, if not better than, regular coffee. Through a very recent study (January 2021), researchers found that decaf coffee actually “contained the highest amount of all phenolic acids,” when comparing a decaf espresso with two other regular espressos.

If you decide to go with decaf, try to find one that has been prepared using liquid carbon dioxide or water (the Swiss Water Process), instead of synthetic chemicals like benzyne. When I owned a health food store years ago, I sold organic Swiss Water Process decaf coffee, as it was the cleanest way to get the health benefits of coffee without too much caffeine – the best of both worlds.

Page last updated Nov. 23, 2020

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© Stephen Sinatra, MD. All rights reserved.

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