Coffee drinkers are often told that drinking too much coffee is bad for them, but a recent study suggests that there are health benefits too – coffee could protect the liver from cancer.
Researchers from the University of Southampton in the UK conducted a systematic review that pooled together the results of 26 separate studies, which involved over 2 million adults.
They found that just one cup of coffee per day reduced the risk of liver cancer by 20%, drinking two cups saw a 35% risk reduction, and up to five cups pretty much halved the risk.
The study showed that even decaffeinated coffee had a positive effect too, although the results were much weaker. This potentially suggests that caffeine may have an additive effect to the antioxidant compounds found in coffee, which are attributed to its protective properties [1].
Liver cancer
Liver cancer is most commonly caused by hepatitis B/C, alcohol abuse or a condition that starts off as fatty liver and becomes what is known as non-alcohol steatohepatitis (NASH).
In the UK, over 5000 new cases of liver cancer are diagnosed each year with an additional 5000 deaths [2].
Previous studies have shown that both caffeinated and decaffeinated coffee have what is called an inverse relationship with liver enzymes [3]. What this means is, if you drink coffee, irrespective of whether it has caffeine or not, it appears to keep down the levels of enzymes that the liver makes.
When these levels rise, doctors are more suspicious that there is an underlying liver condition. When these levels are low, it implies that the liver is healthy – which suggests that coffee may play a part in good liver health.
Coffee and longer living
Coffee may also help some of us to live longer! Observational studies looking at people’s eating habits and their risk of disease and early death showed that people who drank either caffeinated or decaffeinated coffee tended to have longer lives and less likely to have heart disease [4].
Obviously, you can not conclude that coffee protects the heart, or is the elixir of life, but it does suggest that coffee may not be as harmful as first thought when consumed moderately.
Word of warning
Like most things in life, over-doing any one particular thing can negate potential positive effects. We’re all very different on a genetic level, and therefore we’re all likely to respond to both coffee and caffeine differently.
We have to remember that most of these studies are observational, which means that they conclude on potential links and not on cause and effect.
For some people, caffeinated coffee can have very negative effects such as [5]:
- cause headaches
- raise blood pressure (particularly if you already have high blood pressure)
- cause stomach problems or irritate existing stomach problems such as IBS.
- cause insomnia and contribute to sleep deprivation
Caffeine overdose is exceptionally rare, but for people with low natural tolerance to caffeine, drinking decaffeinated coffee could be the solution to some of its benefits whilst negating many of its potential dangers.
Seb is a writer and blogger of food and nutrition. He holds a bachelors and a masters degree in nutrition science, and has studied sports and exercise nutrition at postgraduate level. He specialises in plant-based nutrition and believes passionately that we can all live with a little less meat.
