Should We Drink Coffee?

What does our daily consumption of coffee do to our health and longevity? Here’s our first story.

When food is scarce, our body detects this lack of nutrients and shifts into conservation mode, turning up the process of autophagy, from the Greek auto, meaning self, and phagy, meaning to eat. Autophagy means, quite literally, eating yourself. Autophagy plays two major roles: nutrient recovery (breakdown products re-entering cellular metabolism) and quality control (the removal of superfluous, damaged, or dangerous components).

In the modern context of not just sufficient food, but an excess of it, our baseline rate of autophagy is low, and slips down even further as we get older. A decline in autophagic capacity with age has been described in almost all animals analyzed, including humans. Autophagy appears to not only be necessary for life extension, but also, in some cases, sufficient for increasing longevity. Boosting autophagy alone can lengthen lifespan in mice by an average of 17%, as well as improve their healthspan. No wonder autophagy is at the forefront of so much longevity research.

The most reliable way to kick autophagy into high gear may be to eat less food altogether. But there is a downside to caloric restriction. Starving yourself, as was understated in a major review, “generates discomfort.” There is, however, something we can consume that induces autophagy that many people find comforting: coffee.

We’ve long known that alcohol consumption causes liver inflammation, but an unexpected finding was made by a group of Norwegian researchers back in 1986: coffee consumption was associated with less liver inflammation. Subsequent studies conducted around the world replicated these results. In the United States, for example, those at risk for liver disease who drank more than two cups (475 ml) of coffee a day appeared to have less than half the risk of developing chronic liver disease as those who drank less than one cup. The fact that regular coffee consumption seems protective against the development of fatty liver disease gave researchers an idea. Since autophagy plays such an important role in clearing fat out of the liver, the researchers tested to see whether caffeine might have cell-cleansing properties.

Indeed, it was found to be a potent autophagy stimulant. So, does coffee or caffeine extend the lifespan of model organisms like yeast and worms? Yes … and yes … In mice, coffee rapidly triggered autophagy within hours at a human-equivalent dose, and decaffeinated coffee worked just as well. The autophagy-promoting properties of coffee were independent of the caffeine content. Both regular and decaf also had similar anti-aging effects on another aging pathway in mice. But what about in people?

A systematic review of the health impacts of coffee on liver diseases concluded that “daily coffee consumption should be encouraged” in patients with chronic liver disease. But if coffee enhances autophagy, shouldn’t its benefits extend to a wide range of diseases? Well, coffee intake is also associated with lower risk of kidney disease, along with reduced risk of conditions as varied as gout, Parkinson’s disease, type 2 diabetes, and skin cancer. Decaf was also associated with a range of potential health benefits. The results are all the more remarkable given that many of the studies may have failed to adequately control for smoking and unhealthy food intake, both of which tend to go along with coffee drinking. So, coffee drinkers appeared to be healthier even despite their tendency for less wholesome habits. Does all of this translate into living longer? Apparently so.

We only have observational research on coffee and mortality in humans, but, to date, more than twenty studies around the world following more than ten million individuals over time have found that those drinking three cups (720 ml) of coffee a day had 13% lower risk of death. If practiced throughout adulthood, that would be expected to translate into approximately an extra year of life.

In terms of longevity, three cups of decaf appeared to be just as protective as three cups of regular coffee, so it’s not the caffeine. This is supported by data showing the longevity link regardless of whether people were slow or fast metabolizers of caffeine. If it’s not the caffeine, then what was it? Coffee contains more than a thousand bioactive compounds. The polyphenol chlorogenic acid is the most abundant antioxidant in coffee beans, so researchers started there and found it was indeed able to enhance autophagy in cultured human cells. So, which brands and types of coffee have the most of this autophagy-boosting compound? We’ll find out next.

Chlorogenic acid, the main antioxidant in coffee, enhances autophagy in human cells, which may explain why coffee is linked to a longer life. If everyone drank three cups (720 ml) of coffee a day, millions of healthy years of life could potentially be saved every year in the United States alone. Which coffee has the most chlorogenic acid?

More than a hundred coffees, espressos, cappuccinos, and instant coffees have been tested, and chlorogenic acid contents varied by more than 30-fold. Interestingly, the major contributor to this wide range was the coffee purchased from Starbucks, which had an extremely low antioxidant content. This may be because Starbucks roasts its beans so dark, it destroys it. The more you roast coffee, the lower the antioxidant levels fall. Caffeine is relatively stable to heat, but a dark roast may wipe out nearly 90% of the chlorogenic acid content of the beans. However, the difference between a medium light roast and a medium roast did not appear to matter, at least when it came to boosting the total antioxidant status in people’s bloodstreams after drinking them.

Soy milk in coffee appears to be fine but adding dairy milk or creamer seems to cut the bioavailability of chlorogenic acid down by about 40%.

The freeze-drying and spray-drying processes used to make instant coffee don’t appear to significantly affect chlorogenic acid levels, but the method of preparing fresh coffee does. Brewed coffee has higher chlorogenic acid content than espresso, presumably due to the longer contact time between the water and coffee grounds and the greater ultimate volume. No differences were found between cold brew or hot.

The brewing method can also impact our cholesterol levels. The culprits are two compounds, cafestol and kahweol, which are found in the fines of the coffee grounds, tiny particles that get trapped in the paper filter. This explains why filtered coffee doesn’t raise cholesterol as much as boiled, French press, or Turkish coffee does. If you don’t have optimal cholesterol levels, you should consider sticking to paper-filtered coffee or using instant coffee, which also lacks these compounds. Mesh filters are likely insufficient, as even paper filters sporting “micro perforations” allow more of the cholesterol-raising compounds to slip through, particularly when the coffee is ground especially fine.

And indeed, those drinking unfiltered coffee were found to have higher mortality rates than those drinking filtered coffee––though any kind of coffee may be better than no coffee at all, at least for women. These findings led some to bemoan the growing popularity of unfiltered brews from capsule coffee machines, but if you cut them open, you can see that the little plastic cups actually do have a paper filter inside. However, capsule coffee ends up with more estrogenic chemicals in it, as one would expect from exposing nearly any sort of plastic to hot enough water, but the levels found were low compared to established safety guidelines.

If coffee can extend our lives by boosting autophagy, potentially preventing hundreds of thousands of cases or deaths from various diseases, should everyone be drinking it? Is there anyone who should avoid coffee? We’ll find out next.

Despite the plethora of health-promoting benefits associated with drinking coffee, including a longer life, could there be any “grounds for concern?” I’ve previously highlighted how coffee is not for everyone. People with glaucoma or perhaps even merely a family history of the eye disease may want to stay away from caffeinated coffee, as it can increase pressure in the eye, and exacerbate or contribute to glaucoma. There are case reports of individuals with epilepsy having dramatic decreases in the frequency of seizures after stopping coffee, so avoiding it or limiting yourself to no more than two and a half cups (600 ml) is certainly worth a try if you have a seizure disorder. Coffee may also worsen acid reflux disease.

U.S. and European guidelines for women both suggest reducing caffeine intake to reduce symptoms of urinary urgency and frequency. This makes sense. Caffeine is a mild diuretic, especially at doses found in more than two or three cups (480 or 720 ml) of coffee, though daily consumers may habituate and be less impacted. Surprisingly, though, a meta-analysis of observational studies found no evidence of a link between urinary incontinence and coffee intake, or caffeine more generally. In interventional studies of caffeine reduction, half found a decrease in urinary frequency, but for urinary incontinence, only two studies out of seven found a significant benefit. Again, though, what’s the harm in giving it a try?

Caffeine intake late in the day can certainly disrupt your sleep, but the caffeine in four cups (960 ml) of coffee finished even six hours before bedtime can reduce total sleep time by more than an hour, and that was in younger individuals. Older adults’ sleep appears to be more sensitive to caffeine. The same 400 mg of caffeine, which is less than what’s in a Venti-sized coffee from Starbucks, cuts total sleep time by about an hour in young adults (average age of 24), but that same amount cuts off more than two hours among the middle-aged (average age of 52). What about just a single cup (240 ml) of coffee at dinner? It can indeed cause a significant deterioration in sleep quality.

There are also consistent associations between drinking coffee and certain adverse outcomes during pregnancy, including miscarriage, early preterm birth, and low birth weight. Although coffee consumption has not been linked to common birth defects, it may increase the risk of childhood leukemia. For more on coffee and pregnancy, see my video on how much is too much.

Also, don’t stick it up your butt. A review on the questionable safety of coffee enemas warned against their use, citing reports of colitis, rectal burns, perforation, and fatal electrolyte disturbances.

Keep in mind that daily consumption of caffeinated beverages can lead to physical dependence. It’s no coincidence that Americans alone spend more than $100 billion annually on the stuff. Caffeine withdrawal symptoms can include days of headache, fatigue, difficulty concentrating, and irritability. Ironically, coffee’s tendency to become habit-forming could turn out to be a perk if coffee is indeed confirmed to slow biological aging.