What coffee drinkers had hiding in their livers

Researchers have linked coffee drinking with better liver health before.

But a new study went much further than simply comparing the number of cups people drank with how many eventually developed liver disease.

It also included MRI scans that revealed physical signs of liver damage and an analysis of blood proteins connected to liver function, inflammation and scarring.

No matter how the researchers looked at it, coffee drinkers seemed to have healthier livers.

And because the results were similar for caffeinated and decaffeinated coffee, caffeine may not be the only reason.

A closer look at what coffee may do for the liver

Your liver works around the clock to process nutrients, regulate blood sugar and cholesterol, break down medications and remove potentially harmful substances from your blood.

But liver damage can build quietly.

Fat, inflammation and scar tissue may accumulate for years before noticeable symptoms develop. Over time, that damage can progress to cirrhosis, liver failure or liver cancer.

Researchers at Cedars-Sinai wanted to better understand why coffee consumption has repeatedly been associated with better liver health.

They examined data from 354,957 adults participating in the UK Biobank. None had cirrhosis or liver cancer when the study began.

After a median follow-up of 13 years, the researchers compared liver outcomes among coffee drinkers and people who did not drink coffee.

Compared with non-coffee drinkers, people who reported drinking five or more cups daily had:

• a 32% lower risk of cirrhosis
• a 47% lower risk of liver cancer
• a 42% lower risk of dying from liver-related causes

That does not mean you need to drink five cups a day to benefit.

Signs of protection were evident among people who drank just one or two cups daily, while the overall benefits appeared strongest at approximately three to four cups a day.

Researchers could see the difference

Disease rates told only part of the story.

A subgroup of participants also underwent MRI scans that allowed the researchers to look for less obvious signs of liver damage.

People who drank more coffee tended to have lower levels of:

• fat in the liver
• excess liver iron
• fibrosis, or the buildup of scar tissue
• liver inflammation

That is important because fat, inflammation and fibrosis may be present long before someone is diagnosed with advanced liver disease.

In other words, coffee drinking was not only associated with fewer cases of cirrhosis and liver cancer years later. It was also associated with measurable differences inside the liver itself.

Blood proteins revealed another clue

Proteins can provide important clues about what is happening inside the body, including whether biological pathways tied to inflammation, tissue damage and repair have become more or less active.

Coffee drinkers had higher levels of proteins associated with healthy liver function. They also had lower levels of proteins connected to inflammation and scarring.

The study still can’t tell us exactly how coffee affects the liver. But finding differences in disease rates, liver scans and blood proteins makes the connection harder to dismiss.

The researchers say their next step is to identify the specific compounds in coffee that may be affecting these pathways.

Decaf drinkers shouldn’t feel left out

The liver benefits were similar among people who drank caffeinated and decaffeinated coffee.

That suggests caffeine is probably not acting alone.

Coffee is a complex mixture containing hundreds of naturally occurring compounds. Some may influence pathways involved in inflammation, scarring and the way the liver processes fat and energy.

For now, researchers do not know which compounds — or which combination of compounds — may be responsible for the associations they observed.

Coffee isn’t a substitute for liver-healthy habits

The consistency of the findings is noteworthy. Lower rates of serious liver disease were supported by MRI evidence and differences in blood proteins connected to liver health.

Even so, the researchers are not recommending that people who dislike coffee begin drinking it solely to protect their livers.

“Prevention should continue to focus on maintaining a healthy weight, limiting alcohol, exercising regularly, and managing blood sugar, blood pressure and cholesterol,” says study senior author Dr. Ju Dong Yang of Cedars-Sinai.

And more coffee is not always better. Caffeine can aggravate insomnia, anxiety, heart palpitations and certain health conditions. What you add to your cup matters, too, since large amounts of sugar and high-calorie creamers could work against your metabolic and liver health.

But if you already enjoy and tolerate coffee, this research offers another reason to feel good about pouring a cup — whether it contains caffeine or not.

More reasons to feel good about your coffee

Coffee isn’t a cure-all. But research continues to uncover potential benefits that may help coffee lovers feel even better about their daily habit.

Here are just a few of the ways coffee has been linked to better health:

It’s also important to understand what researchers mean by a “cup.” In many coffee studies, one cup is only 6 to 8 ounces. The 18- to 24-ounce mugs many people use may hold the equivalent of two or three study-sized cups.

Sources:

Coffee Consumption and Improved Liver Outcomes: Clinical, Imaging, and Proteomic Evidence From the UK Biobank — Clinical Gastroenterology and Hepatology

Coffee May Protect the Liver in More Ways Than Scientists Realized — Sci Tech Daily

FAQ: Frequently asked questions about coffee and liver health