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.
There have been a lot of different discussions about coffee’s benefits, including its potential to increase longevity.
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. Even recent studies confirms that coffee may benefit 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
The study in question was published in January of 2016 and has generated a significant amount of interest. For example, the site Eater covered the research soon after it was published.
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.
A cohort study follows a group of people over time. This will often involve looking at a range of lifestyle factors and health outcomes across the research.
A case-control study specifically looks for people with the condition (cases) or without it (controls) and then looks back at how often they were exposed to a risk factor (in this case, coffee).
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:
Data from Kennedy et al., 2016
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.
Other Research
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).
Likewise, the anti-inflammatory and antioxidant effects of coffee have been promoted as potential components of the mechanism (3,4).
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. Recently a new study was released which confirmed that regular coffee consumption reduces liver cancer risk.
The most interesting part of the study was its size, with 30,824 participants and a follow-up period of 16 years. The study looked at the consumption of coffee, green tea, and caffeine intake.
Surprisingly it was only the coffee consumption that reduced liver cancer risk. This brings up the possibility that caffeine intake is not responsible for the association between coffee consumption and decreased liver cancer risk.
In the past, I’ve talked about other health benefits of coffee, so having multiple cups of coffee a day may well be healthy. At least the research at this time supports no significant risks from coffee drinking when it comes to liver cancer.
If you are looking for the best coffee brands and tools to make coffee at your home one of my favorite sites is the Coffee Maven , which has great 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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What does your coffee habit look like? Do you drink a lot of coffee or do you avoid it entirely?