Is coffee good for your health?

“I’m going to cut down on the coffee,” resolves a coffee drinker who may have an addiction problem. Caffeine sometimes lends coffee a negative spin. The withdrawal effects of a caffeine addiction can be pretty bad: headaches, anxiety, mood swings, and nausea. On the other hand, too much coffee at once can make you jittery and on-edge and increase your heart rate. People talk about the “post-caffeine crash". For the first couple hours you’re speeding through your work, and then the energy is gone and you want to keel over. From personal experience, drinking coffee before you sail out on a small boat will make you spew it back out again (apparently it’s from the acids in the coffee).

But many recent studies report the health benefits of coffee. According to these studies coffee may reduce the risk of type 2 diabetes, liver cirrhosis and liver cancer, Parkinson’s, and coronary heart disease to some extent or another. Other studies show that coffee can boost athletic performance and may possibly increase your lifespan. There always seems to be a new study popping up to report some health factoid like:

• Coffee drinkers with a modest intake, two to four cups per day, had a 20 percent lower risk of heart disease compared to those drinking less than two cups or more than four cups.

Okay?! So tomorrow I can wake up, drink three cups of joe, and tell myself, “This daily ritual is making me less susceptible to heart disease!”

Or can I?


A scientific study can only do so much to influence your health habits. There are reports out there saying that it takes more than 6 cups of coffee daily to get any significant health benefits. That’s good news for a heavy coffee guzzler, but 6 cups for me? No thank you. I’d be bug-eyed, anxiety-ridden, and sitting on the toilet for the better part of the day.

Sometimes those health articles have links to the original study, so I clicked on a couple links and found:

Study #1: from the Journal of the American Heart Association about “Tea and Coffee Consumption and Cardiovascular Morbidity and Mortality”

Study #2: from Hepatology about coffee consumption and the risk of liver cancer.

The strengths and limitations of a study have to be considered for it to be scientifically valid. Both studies I looked at follow a large number of participants (about 37,000 participants in one of them) for a long time (13-19 years). The studies tracked how many people got coronary heart disease (CHD) and liver cancer, respectively. The actual number of people diagnosed with CHD (1950 people) and with liver cancer (128 people) was relatively low. The number of participants and the long follow-up are good, but is 128 people big enough for a good statistic? Working with a small number of diagnosed participants could be a limitation.

Other limitations include self-reported data - people may lie about their health habits. Also, the studies attempt to adjust for other health factors like the history for a particular disease (e.g. diabetes), age, educational level, smoking and alcohol habits, weight, etc. These adjustments are made to establish that coffee consumption is the cause, not a correlation.

Interestingly, in the first study, tea and coffee drinkers were found to have opposite health habits. Tea drinkers tended to have healthier habits, whereas coffee drinkers tended to smoke and drink more, weigh more, and even had a lower educational level.

It’s also interesting to compare the health trends for the population samples of different regions. The liver cancer study focused on a Finnish population with high coffee consumption and a low risk of liver cancer. The Finnish population sample is advantageous because the variables in question are much better isolated. Previous studies with Italian and Japanese populations were obscured by higher rates of liver cancer that could be attributed to multiple factors.

These studies also lend some insight into the chemicals at work in tea and coffee. Caffeine and diterpene alcohols in coffee “could increase cardiovascular risk by increasing serum cholesterol and decreasing insulin sensitivity.” But coffee also contains chlorogenic acid with antioxidant properties that could reduce the risk of coronary heart disease. “More research necessary”, of course.

These studies offer fun facts and health bytes, but how much influence do they actually have?

When you get down to it, health advice is simple and straightforward. “Everything in moderation” is a good dose of common sense. Most articles on coffee conclude that coffee has been around for a while, and you don’t need to feel guilty about drinking it in moderation. Too much may get you wired. Too little? Well, you probably don’t need to care. Considering your own personal health background and making your own lifestyle choices speaks to common sense more than following a couple numbers and statistics.