The Good, The Bad, The Coffee

October 30, 2014


After years of research looking at the health impacts of drinking coffee, you’d be forgiven if you weren’t clear about whether it’s good or bad for you.

A recent study published in Molecular Psychiatry brings us closer than ever to knowing why that is. Researchers analyzed the entire DNA sequence of 120,000 coffee drinkers and found at least eight locations on our genes that are linked with coffee drinking, six of which have never been linked to coffee before.

While there are numerous other compounds in coffee that have biological effects, the study further boosts the idea that it’s the caffeine that motivates regular coffee consumption.

Real Benefits

A large number of studies show that consumption of caffeine leads to increased alertness and reduced fatigue. This effect has been demonstrated in people who need a morning jolt, need to stay up late, need to fight sleep loss or battle a cold.

It even works in people who are already in an alert state. Caffeine does this by blocking the effects of adenosine receptors in the heart and brain, causing increase stimulation of the central nervous system and increased heart rate.

In a large, multi-ethnic study involving more than 162,000 participants, those who drank 2-3 cups of coffee every day had about a 40% reduction in the risk of liver cancer or chronic liver disease.

Caffeine seems to affect liver enzymes and the development of cirrhosis regardless of gender, alcohol drinking, or history of hepatitis or liver disease.

The Dark Side Of Coffee

The risk of a caffeine-induced heart attack actually depends on your genes. People metabolize caffeine at different rates depending on the activity of their liver enzymes. Caffeine sticks around in those who metabolize caffeine more slowly.


If you’re the type who gets the jitters after a cup of joe, you’re likely a slow-metabolizer. Studies suggest that if you’re a slow-metabolizer, you’re more likely to suffer a nonfatal heart attack.

Recall that coffee’s stimulant activity is due to caffeine’s ability to block the body’s adenosine receptors. There’s a common genetic variant of the receptor gene that seems to be extra sensitive to caffeine’s effects.

People who categorize themselves as “caffeine-sensitive” likely have this gene variant and usually reduce caffeine intake voluntarily because it impairs the quality of their sleep.

The Final Verdict

Too much of anything is bad for you. The verdict as to whether coffee is good or bad for you is not known unless you have your genes looked at.

You probably already know how you feel and react after a cup or two, and you probably adjusted your intake accordingly or switched to tea.

The research shows that for the general population, the health benefits of coffee consumption outweigh the risks. In the end, it really depends on your genes.