Coffee protects the liver

Onni Niemelä’s research group used Finnish research data to confirm the beneficial effects of coffee on the gamma-GT liver enzyme levels.

Onni Niemelä’s research group used Finnish research data to confirm the beneficial effects of coffee on the gamma-GT liver enzyme levels.

Drinking more than four cups a day reduces the level of the gamma-GT enzyme in heavy drinkers.

A Finnish study recently confirmed that drinking coffee protects the liver from the harmful effects of alcohol. Coffee was found to reduce the levels of the liver enzyme gamma-GT (gamma-glutamyltransferase).

Usually, heavy drinkers have clearly elevated levels of gamma-GT. The threshold of heavy drinking in Finland is 24 portions of alcohol per week for men and 16 portions per week for women. One portion is one 0.33 litre bottle of medium strength beer (alcohol content 4.7 %).

The levels of the gamma-GT enzyme rose most significantly in those heavy drinkers who did not consume any coffee. Heavy drinkers who had more than four cups of coffee per day had noticeably lower levels of gamma-GT.

The effects of coffee were more apparent in men than women.

“The result confirms the previous observation that coffee protects the liver from harmful substances,” says Onni Niemelä, Professor of Addiction Medicine at the University of Tampere.

Elevated levels of the gamma-GT enzyme are a sign that something detrimental is happening to the body. Drinking alcohol, being overweight and taking new medication can all elevate the level of the enzyme.

”A rise in the level occurs during oxidative stress,” says Niemelä.

The research was conducted in cooperation with the National Institute for Welfare and Health in Finland and it used FINRISKI research data which includes health information on 18,899 Finns aged 25—74.

The research population was classified according to alcohol and coffee consumption which enabled comparisons of gamma-GT enzyme levels.

Excessively high levels are accepted

Even small amounts of alcohol can elevate the gamma-GT level a little.

“A doctor does not necessarily pay too much attention to the gamma-GT level if its variation stays within normal limits. This is risky because higher and higher levels have recently been accepted as normal,” Onni Niemelä says.

The range of the normal level is defined by tests which typically pick about 200 healthy individuals and define the normal levels on the basis of their blood tests.

“The problem is that there are increasing numbers of obese people and people also consume more alcohol, so more and more people with elevated levels of gamma-GT are included in these samples.”

In the 1980s, the highest allowed normal level of gamma-GT was 50. Now levels as high as 115 are accepted in middle-aged men. These levels mean that there is already a strain on the body and the liver.

Niemelä thinks that the normal level should be redefined.

”Liver tests should have definite points at which doctors should start paying attention. In the case of the gamma-GT enzyme, a suitable level would be about 70-100.”

It would also help if the doctor knew the patient’s previous test results. If the prior gamma-GT level was 40 and the number has started to rise quite suddenly, this would indicate that the liver is already working overtime even if the level of the enzyme remains below 100. The doctor should then talk with the patient about his or her circumstances and lifestyle so that underlying health problems can be detected earlier.

“The same is true about the other liver enzymes whose levels are tested with the ALAT and ASAT blood tests,” Niemelä says.

The effect varies

Research has shown that drinking coffee can protect against liver cirrhosis caused by alcohol. Coffee has also been noted to alleviate the prognosis of other liver diseases, such as those caused by a virus.

“Research has given quite a clear indication that drinking both coffee and tea is beneficial to the liver. They appear to protect risk groups against developing a liver disease.”

However, it cannot be said that if you drink a lot of coffee you can also booze with abandon.

The effect of coffee depends on the disease and the tissue in question. For example, coffee is detrimental for example when a person has a tendency to suffer from an irregular heartbeat or has problems with sleep.

”Coffee works in liver diseases because it supports the antioxidative defence system. Coffee contains many molecules that have a beneficial effect on the liver and prevent the effects of oxidative stress.”

According to Professor Niemelä, researchers now have a better understanding of the gamma-GT enzyme. In the future it is expected that the level of the enzyme will be used to determine a person’s health in more general ways.

“If the level of the enzyme begins to rise, it can also predict vascular diseases,” Niemelä added.


This story was originally published in Finnish in Aikalainen 7/2013

Original text: Tiina Lankinen
Image: Jonne Renvall
Translation: Laura Tohka