If you’re a grown-up human being, you’re probably a regular coffee drinker. At Resilient Nutrition, we like coffee too - let’s be honest, we made coffee versions of Long Range Fuel in part to satisfy our own cravings. If you’re like us though, you’ve at some point felt confused about whether drinking coffee is good for you, and you might still be unsure about how much coffee you can get away with without any concerns. If you want answers to these questions or just fancy nerding out on the science of coffee, you’re in the right place, for in today’s blog we’ll have a nosey at what we really know about coffee.
Go grab yourself a mug of the stuff and let’s get to it.
- Coffee contains over a thousand compounds and is the primary source of antioxidants in some people’s diets. Its methylxanthines (e.g., caffeine) and chlorogenic acids (CGAs) probably mediate many of its effects on health.
- There are stark differences in the compositions of different coffees. Differences depend on variables such as coffee species, farming practices, roasting methods, and brewing conditions.
- Regarding regular coffee, robusta coffees made using espresso methods are particularly high in caffeine and CGAs.
- Green coffee bean products contain immature, unroasted beans. Very rich in CGAs, they probably have the best chemical profile of all coffee products.
- People who regularly drink 1 to 4 coffees each day live the longest and have the lowest risk of various chronic diseases, such as Parkinson’s disease, obesity, cardiovascular disease, chronic liver diseases, and certain cancers. However, it might be premature to assume that coffee intake per se underlies these associations.
- Base your coffee intake on how much caffeine's in it.
- If your sleep is a priority, try cutting out coffee by no later than 8 h before bed, at least to begin with.
The effects of coffee on health depend on its composition
Coffee contains over a thousand compounds, the combination of which gives coffee its sensory and health properties. The main bioactive compounds in coffee include chlorogenic acids (CGAs), diterpene alcohols (e.g., cafestol), flavonoids (e.g., catechins), hydroxycinnamic acids (e.g., caffeic acid), melanoidins, methylxanthines (e.g., caffeine), minerals (e.g., magnesium), and vitamins (e.g., niacin). So, while some people mistakenly think coffee is basically just tasty caffeine, there’s so much more to coffee than caffeine alone. In fact, studies such as this one report that in some countries coffee is probably the highest source of antioxidants in people’s habitual diets.
Several factors determine the precise combination of substances in a cup of coffee, including type of coffee beans used (genetics matter), farming methods (i.e., traditional or organic), storage practices, roasting processes (e.g., the torrefacto method involves glazing the beans with sugar during roasting), grinding techniques, and brewing conditions (including temperature, pressure, filtration, and duration). As there are so many of these variables, there are huge difference between coffees in contents of chemicals such as caffeine. Notably, these contents are not necessarily true to manufacturers’ claims. In one study, for instance, the caffeine contents of Nespresso® coffee pods ranged from 19 to 147 mg per serving – 51 to 162% of the manufacturer’s claimed values.
Coffee bean matters: arabica versus robusta
If you’re a coffee snob (closet or not), you’ll be familiar with these names. While both are species of coffee (i.e., from the Coffea genus of plants), arabica was probably the first coffee humans cultivated, and it accounts for most coffee worldwide. Endemic to Ethiopia, it’s generally considered the “finest” coffee and tends to have a fruitier, sweeter taste than robusta, which is comparatively bitter. Given this profile, robusta is often used in espresso blends, both for its flavour and for its foamy finish (“crema”).
Regarding composition, arabica typically contains more carbohydrate, less caffeine, and lower antioxidant levels than robusta, and arabica also tends to need more herbicides and pesticides than robusta. So, while few would argue that the best tasting coffees are arabica ones, it’s plausible that many cheaper robusta coffees are at least as good for health.
Coffee roasting matters: regular coffee versus green coffee
If you’ve come across green coffee drinks or extracts, you might be wondering whether they’re good news. Unlike regular coffee, green coffee beans are immature and have not been roasted. As a result, green coffee has a much milder taste than regular coffee, and frankly the green stuff isn’t nearly as tasty. However, since it hasn’t been as processed as regular coffee, green coffee tends to be richer in health-promoting compounds such as CGAs, the most abundant antioxidants in coffee. Tightly-controlled research has shown that green coffee bean products can meaningfully improve some aspects of health – more on this later.
Coffee brewing methods
Next, the way coffee is brewed influences its composition. Variables such as pressure, temperature, filtration method, and duration of brewing all influence what ends up in the final drink. For example, a recent study assessed the effects of 8 different brewing methods on the composition of coffee. Importantly, the same coffee matter was used for all methods. Comparing espresso (3 types), moka, French press, and filter coffee (3 types), the traditional espresso method yielded nearly twice as much caffeine and CGAs per unit volume as other brewing methods, although you should remember there’s not much coffee in an espresso – only 17 to 30 ml, in this instance.
What about decaff?
Decaff can be very helpful if you love coffee and are trying to reduce your caffeine intake. The problem is that it’s not just caffeine that’s lost during decaffeination – other key bioactive compounds such as CGAs are lost too. Probably because of this, decaff just doesn’t seem to have the same effects on health as regular coffee.
Not all decaff is made equal, however. While many decaff products are made using less-than-ideal solvents (e.g., methylene chloride) during the caffeine extraction process, the Swiss water decaff process doesn’t use such chemicals, instead using water. I wouldn’t lose sleep over this detail, but I thought I’d mention it in case you’re neurotic about that sort of thing.
So, is good coffee good for you?
Going by what we’ve covered so far, you might have guessed that it’s hard to assess the effects of coffee on health in part because there’s so much variability in the contents of different types of coffee. Deciphering coffee's effects is further confounded by how differently individuals respond to coffee. This variation depends on factors such as a person’s genetics, health, and whether he or she habitually consumes coffee. Caveats aside, let’s look at some of the relevant research.
One way of assessing the potential effects of coffee intake on health is to ask people how much coffee they usually drink or have them track their diets for several days and then monitor their health over several years. While this type of study design has many limitations - not the least of which is how (in)accurately people report their diets - it can help identify potential diet-disease relationships. And where this type of research has unveiled possible associations between coffee consumption and health, we’ll briefly consider mechanisms that might underlie these effects.
Coffee and brain health
As described in a previous blog, the caffeine alone in coffee can be used to acutely enhance important cognitive functions, especially when short on sleep. With respect to long-term brain health though, people who regularly drink 1 or 2 coffees a day have slightly lower risks of going on to become cognitively impaired – the kind of age-related deterioration in mental faculties that leaves you constantly trying to remember where you put your keys. This analysis found a J-shaped association between coffee intake and risk of developing cognitive dysfunction, meaning that while moderate coffee intake associated with better brain function, higher coffee intakes were not better. This type of nonlinear relationship is common to coffee intakes and risks of several diseases, so please bear in mind that more is not necessarily better!
Regarding neurodegenerative diseases, it’s not so clear whether coffee intake associates with risk of dementias (e.g., Alzheimer’s disease), although the most recent analysis suggests that coffee consumption has a weak protective effect. The association between coffee intake and Parkinson’s disease seems to be a little stronger, and people who regularly drink about 3 cups a day had the lowest risk of Parkinson’s in this analysis. Interestingly, Parkinson’s patients who drink coffee also appear to experience slower disease progression. As dysfunction of dopaminergic brain circuits is at the core of Parkinson’s disease pathology, it’s plausible that some of this relationship is driven by the effects of the caffeine in coffee on dopamine signaling in the brain. If you’re interested in this, be sure to read this blog about caffeine.
Coffee and bodyweight
Moving now to other aspects of health, many of us are interested in whether drinking coffee can help us shed some pounds. While research hasn’t consistently shown large effects, people who drink more coffee tend to be slightly leaner, and this might be truer of men than women. It seems likely that CGAs underlie much of this association, for CGA-rich green coffee extracts have repeatedly been shown to support weight loss, perhaps by accelerating fat burning during sleep. Caffeine might make some small contributions to weight regulation too, for it acutely increases energy expenditure and slightly shifts the mix of fuels your body burns in favour of greater fat use.
Coffee and diabetes
If drinking coffee affects bodyweight regulation, we might expect it to also affect blood sugar control. Sure enough, coffee intake appears to be inversely related to risk of developing type-2 diabetes, and this is true of both caffeinated and decaffeinated coffee. Scientists don’t really know how to explain this relationship, but coffee’s antioxidant content, effects on energy expenditure, and possible effects on the gut microbiota might all be at play.
Coffee and cardiovascular health
Moving on to the cardiovascular system, people who drink coffee are less likely to develop cardiovascular disease. Blood pressure is central to cardiovascular health, so it’s interesting that caffeine alone acutely raises blood pressure more than an equivalent dose of caffeine from coffee. This might be in part explained by the fact that CGAs in coffee routinely reduce blood pressure by improving blood vessel function.
One nuance to note here is that consuming certain types of coffee can raise total cholesterol, low-density lipoprotein cholesterol, and triglycerides in your blood, none of which would please most conventionally trained doctors. These effects are largely due to some of the diterpenes in coffee, and espressos tend to be higher in these diterpenes than filter coffees or instant coffees. This means that you might be able to nudge your blood lipids in specific directions by switching your coffee choices, although I’m not convinced that such changes are clinically meaningful.
Coffee and liver function
Finally, people who drink more coffee are less prone to developing multiple chronic liver diseases, perhaps in part through polyphenols in coffee both protecting against fibrosis and keeping liver enzymes in check. Coffee drinkers also seem to be less likely to be struck by liver cancer, which may relate to coffee’s antioxidant and anti-inflammatory actions.
I find the fact that people who drink lots of coffee are less likely to experience liver problems especially interesting. This is very speculative, but I think there might be some so-called “reverse-causation” going on here. Could it be that rather than coffee intake protecting the liver, people who have better liver function to begin with drink more coffee? I think so. Consider this: While in healthy people the average half-life of caffeine is around 6 h (meaning that after ingesting caffeine, it takes roughly 6 h for blood caffeine concentration to come down to half its peak value), caffeine’s half-life can be much longer (several days) in people who have liver disease. As high blood concentrations of caffeine can provoke anxiety and interfere with processes such as sleep, people with poor liver function might self-select lower coffee intakes.
How much coffee should you drink?
Looking across all relevant epidemiological studies, people with the best health and longest lifespans tend to drink 3 or 4 coffees a day. As discussed at the start of this blog, however, there are HUGE differences between coffees. As one example, 4 cups of a typical instant coffee contain about 200 mg caffeine. However, 4 cups of Devil Mountain Coffee Black Label contain over 6,000 mg caffeine. Yes, you read that correctly - that’s a 30-fold difference between them. And yes, consuming 6,000 mg caffeine in a day could have mortal consequences for some people. So, it’s hard to be prescriptive here. Also consider that:
- There is great between-person variation in metabolism of compounds such as caffeine.
- Why you’re drinking coffee (i.e., for the taste, or to enhance some part of your health) affects what is the “optimal” dose for you.
- The composition of the rest of your diet also influences how much coffee is ideal – if you drink lots of tea or consume lots of cocoa products, for instance, you’re probably consuming lots of caffeine and polyphenols from these items too.
Keeping this in mind, basing your coffee intake on its caffeine content is a smart option. It’s not a perfect solution, but it’s probably at least as good as the alternatives. For more on caffeine, check out this blog, which also contains info about who might want to restrict caffeine intake. The only thing I’ll add to the previous blog is that it seems that coffee might slightly raise the risk of some bone fractures in women, perhaps through minor effects on sex hormones. If you’re doing resistance training and consuming enough bone-building nutrients (e.g., calcium, protein, vitamin D3), you probably shouldn’t be concerned about this though.
As elaborated in our free e-book, it also makes sense to maximise the diversity of your diet, when possible. Different foods contain different health-promoting chemicals, and consuming a wide array of different foods and drinks also minimises the likelihood of you consuming too much of food constituents that can be toxic in excess. So why not have a coffee here, some cocoa there, and cup of tea now and then?
Finally, regarding timing of intake, I stand by my previous starting point: If sleep is a priority, stop consuming caffeine intake by at least 8 h before you plan to go to bed.
I’ll have a black Americano, please
In summary, the science generally shows that people who regularly drink modest amounts of coffee – perhaps 1 to 4 cups a day – have better health than people who drink more or less coffee, respectively. However, there are enormous differences both between different coffees and between how different people respond to coffee. While it’s hard to say that drinking coffee causes these people to be more robust, carefully controlled experiments generally show that coffee and its key compounds are healthy.
Basically, drinking “normal” amounts of coffee is probably good for you, so if you like coffee you should experiment with coffees to find out what works for you!
Disclaimer: Unsurprisingly, I wrote this blog under the influence of coffee – since I’m in Italy right now, I’m currently enjoying some Lavazza coffee made using an old-fashioned moka pot. Yum.