Traditionally, coffee tends to be viewed as a fairly unhealthy habit, especially in relation to those of us that rely on coffee for energy. But, we’re starting to realize that coffee can actually be a pretty healthy drink. After all, it is filled with a range of nutrients, antioxidants and other compounds from plants.
But, is coffee good for your liver?
That may seem like an odd question, but recent research (Kennedy et al., 2016) has suggested that it just might be. Specifically, the authors of this study were interested in a health condition called cirrhosis of the liver.
This is a pretty major health condition, killing more than 1 million people globally every year. Liver cirrhosis can often be the result of excessive alcohol or food consumption and can be challenging to fight (1).
The Study Itself
In the study, the authors conducted a meta-analysis of previous research, looking for studies that had considered the relationship between coffee consumption and cirrhosis.
They found a total of 9 relevant studies that fit their criteria. Of these studies, 5 looked at cohorts, while the other 4 involved a case-control approach.
In general, most of the studies showed a dose-dependent impact of coffee. So, as the consumption of coffee increased, the risk of cirrhosis decreased (this was true in all but one of the studies). The combined risk ratios from the study can be seen in the image below:
The graph looks at the risk ratios of 1-4 cups of coffee per day, compared to people who consumed no coffee. This means that a 1 cup of coffee per day was associated with a 22% decrease in the risk of cirrhosis and that decrease got stronger with more cups of coffee.
A similar relationship was observed when just the cohort studies were considered or for just the case-control studies.
Strengths and Limitations
A major strength of this research was that the authors looked at outcomes from a range of different studies. This resulted in a pretty large sample size. Additionally, that approach meant the authors could show that similar outcomes were present across multiple studies.
By doing this, the authors showed that the relationship between coffee and cirrhosis was not simply caused by the experimental design of one study.
Nevertheless, the study did also have limitations. In particular, it was limited by the observational nature of the research.
Now, observational research is important.
It can be critical for looking at relationships that we simply couldn’t examine in experimental studies. In this particular case, it would be very difficult to actually conduct an experimental study on the topic. In fact, such a study would probably be considered unethical.
So, the observational approach was important. Nevertheless, it is still limited.
Observational studies can’t tell cause and effect.
In this case, it is possible that people with a lower risk of cirrhosis tended to consume higher amounts of coffee. For example, cirrhosis is often associated with excessive drinking or eating. It is reasonable to argue that people who drink coffee often tend to be less likely to drink or eat excessively.
However, this study and the individual studies that were considered did try to control for as many factors as possible. Doing that helps to reduce the risk that the observed relationship was caused by any other factors, like reverse causation.
The meta-analysis nature of this paper actually made it more difficult to figure out the relationship between coffee consumption and cirrhosis. In particular, all of the studies took alcohol consumption into account. But, only some of the studies looked at other risk factors, like obesity.
In general, the approaches of the researchers mean that it is likely that coffee decreases the risk of cirrhosis of the liver. However, without randomized controlled trials, we cannot know for certain.
One way of looking at the accuracy of the observed relationship is to see what other studies showed.
For example, experimental research has shown that coffee can reduce the deposit of collagen and fat accumulation in the liver, which may be a possible mechanism for how coffee can fight liver cirrhosis (2).
Even though more research is certainly needed, these factors do show that the concept of coffee decreasing liver cirrhosis is feasible.
Is Coffee Good for Your Liver?
The relationship between coffee consumption and liver cirrhosis is a fairly new area of study. Because of that, there is still a lot we do not know.
Even if coffee consumption really does decrease the risk of liver cirrhosis this doesn’t necessarily mean that you should load up on your coffee consumption.
For one thing, researchers don’t know the mechanism behind coffee’s impact on cirrhosis. So, this might be limited to specific types of coffee or methods of brewing. Likewise, the effect could occur for some groups of people but not others.
It’s also worth noting that the ability of coffee to fight cirrhosis isn’t strong enough to negate the effects of lifestyle choices (like excessive drinking) that can damage the liver. Realistically, if you want to improve your liver health, you need to improve your lifestyle in general. Coffee might be a factor in that change, but it certainly can’t be the only approach you take.
Nevertheless, in the past, I’ve talked about other health benefits of coffee, so having multiple cups of coffee a day may well be healthy, regardless of the answer to the question ‘is coffee good for your liver?’.
For that matter, even if coffee isn't good for your liver, there isn't much evidence that it will cause harm.
There are also many places to find information about the best coffee brands and tools to make coffee. One of my favorites is the site The Coffee Maven, which has some amazing information and guides.
Just make sure you don’t load your coffee up with cream and sugar, otherwise the negative impacts of your coffee will probably be more significant than the benefits.
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Better health starts in the kitchen, with the food that you eat and the meals you prepare. Getting the best outcomes involves making good choices about the food and the ingredients that you use.
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What does your coffee habit look like? Do you drink a lot of coffee or do you avoid it entirely?