Can you imagine how unproductive the American office worker would be if coffee wasn’t widely available? I shudder to even consider the prospect of this awful, dystopian world.
Besides water and tea (and I have much to say about how beneficial it is to drink green tea), coffee is the most popular beverage in the world. According to Statistic Brain, 54% of Americans over the age of 18 drink coffee on a daily basis – that’s more than 100 million people. Out of these, 60% claim they need coffee to start their day, and 54% claim they “need coffee to feel like their self".
Coffee, due to its caffeine content, is pretty damn addictive. At one point in my life, I went from having barely drank coffee in my life to six cups a day in 10 weeks. And trying to quit after that? Ugh! Intense headaches and no motivation to get out of bed. Personally, I suspect that the addictive nature of caffeine has fueled some of the popular perception that coffee isn’t particularly healthy, or at least is a somewhat “risky" thing to drink regularly.
Luckily, this perception is inaccurate. While there are some people who are very sensitive to caffeine, the rest of us can drink coffee without a problem. Even pregnant women can likely drink up to two cups of coffee per day without negatively impacting the child. And for the rest of us, coffee is actually pretty damn healthy!
What’s In A Cup Of Coffee?
Before diving into the health benefits of coffee, it is worth knowing what is actually in the coffee you drink. There are hundreds of different compounds in coffee, but there are a few that are most important.
- Caffeine. Duh. This is the main psychoactive component of coffee, and by far the most studied. Many of the health effects described later in this article are due to caffeine (which, of course, you can get from non-coffee sources). It’s that thing that wakes you up, but it’s also the thing that might make you irritable and restless.
- Chlorogenic acids. These are phenolic compounds, 45 of which have been found in coffee thus far. They also are responsible for much of the health impact of coffee – phenolic compounds are antioxidants and do a lot of good stuff.
- Diterpines. Primarily cafestol and kahweol. These guys help give coffee its bitter taste, and they help fight cancer. For what it’s worth, they also are linked to higher cholesterol levels, if that’s something you’re concerned about.
While you might expect that these components will exist in roughly the same proportions in each cup of coffee, you would be mistaken. For instance, the amount of caffeine in a cup of coffee varies dramatically, even when purchased from the same coffee shop on a different day. Many things can affect the caffeine content: the variety of bean, roasting method, particle size, brewing time, and the proportion of coffee to water.
There really is a science to coffee, and the way it is prepared will have an impact. Covering all of these differences is beyond the scope of this article. However, it is worth noting that lighter roasts have more of the healthy chlorogenic acids than dark roasts (though it is unclear whether lighter roasts have more caffeine, as rumored). Instant coffee is also loaded with chlorogenic acids. To maximize the health benefits of coffee, it is better to choose a light roast or instant coffee…which is a bummer, because my favorite is French roast. Oh well.
Health Benefits of Coffee
Drinking coffee may feel as though it gives you superpowers in the morning, but it also does a whole host of nice things for your body behind the scenes.
Coffee, The Brain, and Cognitive Function
Let’s start with the health impact of coffee and caffeine on the brain – an area that I personally find most compelling. Diseases such as Alzheimer’s and Parkinson’s are debilitating for the elderly, and can be devastating to the families of those afflicted (particularly in the case of Alzheimer’s). Unfortunately, there are no cures yet.
But there are ways to prevent the onset of these diseases, and caffeine seems to be one of the best. While the mechanism of action is not fully understood, it appears that caffeine protects against Alzheimer’s and Parkinson’s by protecting the integrity of the blood-brain barrier.1 A 2010 meta-analysis found caffeine to substantially reduce Parkinson’s disease risk – there was an overall risk reduction of 25%, with a linear dose-response.2 In other words, each additional cup of coffee should decrease your risk in proportion to how much caffeine it contains. However, it does appear that estrogen may block some of caffeine’s neuroprotective effects, so women undergoing hormone replacement therapy may not benefit.3 A 2007 review found a decreased risk of Alzheimer’s in coffee drinkers,4 and lifetime caffeine exposure and current caffeine consumption have a positive impact on cognitive function in elderly women.5
But wait, there’s more! Total coffee and tea intake has been associated with a reduced risk of brain tumors.6 Not only that, but a 2015 meta-analysis showed that coffee and caffeine are significantly related to a reduced risk of depression; each additional cup of coffee per day reduces the risk of depression by 7%!7
Some of the more exciting research regarding caffeine’s impact on the brain is about how it affects cognitive function in healthy individuals. Much of this research is summarized in Nehlig 2010,8 a paper which I would highly recommend to interested readers.
“It has been repeatedly demonstrated that caffeine decreases reaction time, increases vigilance and attention, and has positive effects on mood (at the doses used in most studies that will be considered here)."
Here are some more specifics and qualifications:
- “…caffeine facilitates learning in tasks in which information is presented passively; in tasks in which material is learned intentionally, caffeine has no effect."
- “…caffeine does not seem to consistently improve immediate free recall of words, letters and digits. Caffeine facilitates performance in tasks involving working memory to a limited extent, but hinders performance in tasks that heavily depend on working memory."
- “It is well-known that caffeine ingestion leads to dose-dependent increased energetic arousal. At low doses, caffeine improves hedonic tone and reduces anxiety, while at high doses there is an increase in tense arousal, including anxiety, nervousness, and jitteriness. Caffeine improves concentration and help to focus mainly by eliminating distractors."
- “Caffeine can apparently improve performance directly over a wide variety of mental tasks, and indirectly by reducing decrements in performance under suboptimal alertness conditions. The efficacy of caffeine under states of reduced alertness is quite consistent."
In other words, caffeine is not a perfect performance enhancer, but it definitely has some serious positives. In particular, it seems to be helpful for those who are sleep deprived or otherwise tired. Note that it is also possible that some of these beneficial effects are merely the result of correcting for caffeine withdrawal symptoms that subjects may have been experiencing; whether or not this is the case is up for debate. In either case, it is clearly beneficial for the brain.
Coffee And Cancer
Coffee, perhaps due to its phenolic compounds, substantially reduces the risk of various types of cancers. For instance, Yu et al. (2011) found that each additional cup of coffee per day reduced the risk of cancer by 3%.9 Specifically,
“In subgroup analyses, we noted that, coffee drinking was associated with a reduced risk of bladder, breast, buccal and pharyngeal, colorectal, endometrial, esophageal, hepatocellular, leukemic, pancreatic, and prostate cancers."
Other studies have investigated the effects of coffee on different kinds of cancer. For instance, a 2012 meta-analysis found that each cup of coffee conferred an 8% reduced risk of endometrial cancer,10 and a meta-analysis from 2011 showed that each additional cup reduced the risk of pancreatic cancer by 4%.11
Perhaps the most impressive cancer reduction is that of liver cancer; a 2007 meta-analysis found that an increase of 2 cups of coffee per day was associated with a 43% reduced risk of liver cancer!12 In fact, coffee seems to just be great for your liver in general. Cadden et al. (2007) found that coffee prevents the elevation of liver enzymes, and reduces the risk of cirrhosis and hepatocellular carcinoma (liver cancer).13 A more recent review, Saab et al. (2014) found that coffee consumption is beneficial in a wide range of liver diseases, and recommended that coffee consumption be promoted among those with liver issues.14 Note that, consistent with our discussion above, the study found that filtered coffee appears to have more benefits than unfiltered coffee.
Coffee and the Cardiovascular System
Since caffeine is a stimulant, there are many who are concerned that drinking coffee may not be good for your heart. This fear is primarily centered on the belief that drinking coffee will increase blood pressure. What does the evidence say?
Overall, the evidence is mixed but promising for coffee drinkers. One review of prospective observational studies found that drinking more than 3 cups of coffee per day was not associated with an increased hypertension risk, but that 1-3 cups per day is associated with a slight increase.15 In contrast, a more recent meta-analysis found no significant effects from coffee on blood pressure.16 A different meta-analysis found that hypertensive individuals may experience an acute increase in blood pressure when drinking coffee, but that they experienced no increase in blood pressure with long-term consumption of coffee.17 In other words, those who don’t normally drink coffee may experience a short-term spike in blood pressure, but habitual coffee drinkers won’t have elevated blood pressure compared to non-drinkers.
The story doesn’t end there. Interested readers can refer to Bonita et al. (2007) for a review of the mechanisms by which coffee components may influence cardiovascular health and risk factors.18 In practice, these effects provide some benefits with respect to cardiovascular disease outcomes (O’Keefe et al, 2013).19
“From a cardiovascular (CV) standpoint, coffee consumption may reduce the risk of type 2 diabetes mellitus and hypertension, as well as other conditions associated with CV risk such as obesity and depression; but it may adversely affect lipid profiles depending on how the beverage is prepared. Regardless, a growing body of data suggests that habitual coffee consumption is neutral to beneficial regarding the risks of a variety of adverse CV outcomes including coronary heart disease, congestive heart failure, arrhythmias, and stroke. Moreover, large epidemiological studies suggest that regular coffee drinkers have reduced risks of mortality, both CV and all-cause."
A gigantic meta-analysis performed on 1.28 million subjects found that 3-5 cups of coffee per day was associated with a decrease in cardiovascular disease risk by about 10%, and that even heavier consumption did not elevate risk.20
Coffee appears to be dramatically beneficial with respect to diabetes. A 2005 review found that drinking 4-6 cups of coffee per day reduces the risk of type 2 diabetes by 28%, and 6+ cups per day reduces the risk by 35%.21 Consistent with these findings, a more recent meta-analysis on over 450,000 participants found that each additional cup of coffee per day reduced the risk of diabetes by 7%.22 It is worth noting that those who drank decaf coffee had a similar risk reduction, so it is not the caffeine that confers this benefit.
Finally, I should point out that filtered coffee removes more of the diterpine compounds – cafestol and kahweol – which increase serum lipids or cholesterol levels. Boiled or unfiltered coffee doesn’t remove these compounds, and is thus more likely to raise cholesterol levels. Conventional wisdom is that we should aim for lower cholesterol levels, but there are also many nutritionists (or just hobbyists like myself) who believe that high cholesterol is fine, if not a good thing. I’ll leave it to you to determine whether you care about this effect or not.
Coffee and Dental Health
Coffee has been known to stain teeth, but this is purely a cosmetic issue. It also isn’t exactly conducive to having fresh breath. Not to downplay these concerns, but coffee may on the whole be beneficial to your oral health.
Some evidence suggests that coffee reduces the risk of dental caries (cavities) when taken straight black; adding milk and sugar ameliorated this benefit.23 It appears that the antioxidants in coffee make your teeth less adhesive, so bacteria don’t stick to them as well. A recent study found that coffee consumption was associated with a small reduction in periodontal bone loss, and no evidence of harmful effects was found.24
Coffee and Hydration
It is commonly believed that drinking coffee causes dehydration, and some recommend that for every cup of coffee you drink, you need an extra cup of water beyond the normal recommendations. That coffee makes me feel the need to pee far more often doesn’t help.
But it turns out that coffee may not be as dehydrating as people think. For instance, Ruxton (2008) concludes that
“The available studies on hydration found that caffeine intakes up to 400 mg per day did not produce dehydration, even in subjects undergoing exercise testing. It was concluded that the range of caffeine intake that appeared to maximise benefit and minimise risk is 38 to 400 mg per day, equating to 1 to 8 cups of tea per day, or 0.3 to 4 cups of brewed coffee per day."25
Perhaps a higher caffeine intake than that may cause dehydration, but there are not enough studies with such high consumption to make that conclusion.
A more recent study of 50 males consuming 4 mg/kg of caffeine (the equivalent of 270 mg of caffeine, or 2-3 cups of coffee, for someone who weighs 150 lbs) found that coffee has an equal hydration effect as water.26 In other words, those who consume coffee in moderation should be able to count a cup of coffee as the equivalent as a cup of water in determining their overall fluid intake for hydration status. The researchers acknowledged that high doses of caffeine in individuals who don’t normally consume caffeine will cause an acute increase in urine volume, however.
Coffee and Exercise Performance
Caffeine is often added to pre-workout supplements, perhaps partly for marketing purposes: it helps get people to buy your product when they can say that they actually felt its effects acutely, something that caffeine will surely do. But it actually does benefit exercise performance, though it isn’t entirely clear-cut what it will benefit and how much needs to be consumed to experience those benefits.
There appears to be substantial agreement that caffeine improves endurance performance. In addition, there is some evidence that coffee and caffeine itself have similar benefits for endurance training when consumed one hour before the bout of exercise.27
In high doses, caffeine is considered a performance enhancing substance. But what about more normal doses? A review by Spriet (2014) addressed this question by looking at studies using a “low" dose of 3 mg/kg, or about 200 mg (2 cups of coffee) for most individuals, finding that there are performance improvements.28 To summarize the findings:
“It has long been known that moderate to high caffeine doses (5–13 mg/kg bm) ingested ~1 h before and during exercise increase endurance exercise performance in laboratory and sport field settings. Recent work also suggests that caffeine is ergogenic in some short-term high-intensity exercise and sport situations and also in team-sport simulations. Lower caffeine doses (≤3 mg/kg bm, ~200 mg) taken before exercise also increase athletic performance, and recent evidence has demonstrated an ergogenic effect of low and very low doses of caffeine taken late in prolonged exercise. Low caffeine doses do not alter exercise-induced changes in peripheral whole-body responses to exercise and are associated with few, if any, side effects. Low doses of caffeine (~200 mg) have also been shown to improve vigilance, alertness and mood, and improve cognitive processes during and following strenuous exercise."
Coffee and Mortality Risk
Ahhh, mortality risk. The motherlode of health benefits! While causality has yet to be established, there is a strong association between reduced mortality risk and drinking coffee.
A very large study conducted by Freedman et al. (2012) measured the association between all-cause mortality risk and coffee consumption in over 400,000 individuals.29 They found that drinking coffee reduces the risk of death from all causes by a few percentage points, whether drinking caffeinated or decaf coffee.
“Adjusted hazard ratios for death among men who drank coffee as compared with those who did not were as follows: 0.99 (95% confidence interval [CI], 0.95 to 1.04) for drinking less than 1 cup per day, 0.94 (95% CI, 0.90 to 0.99) for 1 cup, 0.90 (95% CI, 0.86 to 0.93) for 2 or 3 cups, 0.88 (95% CI, 0.84 to 0.93) for 4 or 5 cups, and 0.90 (95% CI, 0.85 to 0.96) for 6 or more cups of coffee per day (P<0.001 for trend); the respective hazard ratios among women were 1.01 (95% CI, 0.96 to 1.07), 0.95 (95% CI, 0.90 to 1.01), 0.87 (95% CI, 0.83 to 0.92), 0.84 (95% CI, 0.79 to 0.90), and 0.85 (95% CI, 0.78 to 0.93) (P<0.001 for trend). Inverse associations were observed for deaths due to heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections, but not for deaths due to cancer."
To translate, drinking one cup of coffee per day reduced the risk of death by 6%, drinking 2-3 cups per day reduced the risk by 10%, drinking 4 or 5 cups was associated with a 12% decrease in mortality, and drinking 6 or more cups reduced the risk by 10%. In other words, moderate consumption of coffee may help you cheat death a little longer.
Healthy Ways to Consume Coffee
By now, surely you are convinced that coffee is not only safe, but a healthy thing to consume in moderate amounts on a daily basis, despite the stigma against it. That being said, not all coffee is equal, and there are both good and bad ways to take it.
First things first – ditch the cream and sugar. Sugar is bad for you, period. Cream will add a lot of calories to your coffee, but won’t add any real benefits. Most creamers are very unhealthy. Follow this rule alone – that is, take your coffee straight black – and you won’t jeopardize the health benefits of coffee by adding a bunch of harmful crap to it. Coffee is also a crop that is heavily sprayed with pesticides, so it is worth springing for organic if you can afford it.
Not everyone can handle the deliciousness that is black coffee. Luckily, there are still things you can put in your coffee to improve the taste and texture without sacrificing your health. Here are a few suggestions:
- Personally, I like to add coconut oil and cinnamon to my coffee. The cinnamon is very healthy and adds flavor. Coconut oil contains healthy medium-chain triglycerides (MCTs) which boost energy. The coconut oil also makes it a little more “creamy", for those of you who need to replace unhealthy creamers.
- Drop a square of uber-healthy dark chocolate into your cup and let it melt. The darker, the better. Aim for a minimum of 70% cacao content.
- Try using egg yolks as an emulsifier. Egg yolks are super healthy and are loaded with micronutrients. Plus, they are a breakfast food, so they sort of “go" with coffee well. Here’s a recipe.
- Something called “Bulletproof Coffee" seems to be all the rage nowadays. It’s your standard black coffee with some added grass-fed butter and some MCT oil (such as that from coconut oil) thrown into a blender. Here is a recipe, straight from the inventor. This guy is selling his own butter and MCT oil, but they are overpriced. You can make this yourself with grass-fed butter and coconut oil.
- Will Brink created what he calls “Bomb Proof Coffee", which contains added cocoa powder (make sure it isn’t “Dutch Processed"), l-tyrosine, creatine, and coconut oil. These videos describe what is in it and how to make it, and this article explains the science behind why the ingredients should be included.
With a little creativity, I’m sure you can come up with your own healthy additions. Note that coconut oil seems to be a common one, and is quite delicious. Side benefit: it keeps my lips from getting chapped. My preferred brand is Viva Labs, which is cheap and high quality. You can get yours here.
Besides these various add-ins, the method you brew your coffee also has an impact. I’ll admit that I’m out of my league here – I just use a single-serving K-cup machine. Nevertheless, there are some differences in what compounds different brews will produce:
- Standard drip coffee maximizes caffeine content and decreases diterpines
- French press doesn’t filter out diterpines
- Single-serve machines reduce both caffeine and diterpine content
- Instant coffee reduces caffeine and filters out nearly all diterpines
- Cold-brew coffee has ambiguous effects on caffeine and retains most of the diterpines
Different brewing methods also affect the flavor of your coffee. You can find amusing but unscientific taste tests from Thrillist and Huffington Post. Thrillist recommended the AeroPress machine in their test (currently about $34 on Amazon), while HuffPo recommended the Chemex (currently $36 on Amazon).
Instant coffee, despite its taste, is a healthy way to go for those concerned about cholesterol. For anyone else, the French press results in a more “pure" product than the drip or single-serve methods (and here is a quality French press for about $25). Cold-brewed coffee is about two-thirds less acidic than the other methods, so it is less likely to upset your stomach and would be better for those with acid-reflux (and perhaps is better for your teeth?). This involves steeping ground coffee in water for 12+ hours in a cool environment.
It is a very lucky thing for the world that coffee is such a healthy drink. Do not be afraid to indulge yourself and have a few cups of coffee per day. It’s a fantastic part of a good morning routine.