Timothy Naimi, University of Victoria, The Conversation
There is growing evidence of health harms from alcohol, including drinking at levels that were previously considered “moderate.” (photo StockCake)
Research has revealed a steep increase in liver disease in recent years. Meanwhile, there is growing evidence of health harms from alcohol, including drinking at levels that were previously considered “moderate.” These developments make a persuasive case for viewing alcohol consumption from a public health perspective.
As an internal medicine physician and alcohol epidemiologist, I’m interested in the overlap between liver disease and alcohol use among patients and in the general population. As it turns out, these topics are closely related, but maybe in surprising ways.
The liver is essential: humans need it to live. The liver contributes to metabolism and food storage, produces proteins that help with blood clotting and plays a vital role in the immune system.
At the cellular level, alcohol is a toxic substance that is metabolized (broken down) primarily in the liver. When the dose of alcohol is too high, liver cells become inflamed and damaged (liver inflammation is called hepatitis).
Over time, inflamed or damaged cells are replaced by fibrosis, which is the replacement of normal liver tissue with scar tissue, resulting in cirrhosis, or severe scarring and liver dysfunction. Cirrhosis can be fatal on its own and can also lead to liver cancer.
How does alcohol contribute to liver disease?
Liver disease caused by alcohol is referred to as alcohol-related liver disease or ALD, previously called alcoholic liver disease. The heaviest drinkers, often those who have alcohol use disorder (AUD), can develop cirrhosis and liver failure.
But alcohol-related liver disease does not only affect people with AUD/heavy drinking. A growing body of evidence suggests chronic alcohol use at lower levels may also impact liver function and lead to disease, particularly among those with other risk factors for liver disease.
Patterns of alcohol consumption are also important, including among those who may not consume high amounts of alcohol on average. For example, binge drinking (defined as men consuming five or more drinks or women consuming four or more drinks per occasion) is a pattern of consumption that is very damaging to the liver because it results in high blood alcohol concentrations.
Binge drinking can be harmful to the liver, even among people who don’t drink very much on average or don’t have an alcohol use disorder.
Why are deaths from liver disease increasing?
Deaths from liver disease have been increasing dramatically in Canada and the United States over the past two decades. A key factor is increased alcohol consumption during the same period, but this has been trending down over the past couple of years. Between 2016 and 2022, Canadian deaths from alcohol-caused liver disease increased by 22 per cent.
But alcohol isn’t the only key contributor to the rise in deaths from liver disease. Another is the rise of a condition called metabolic dysfunction-associated steatotic liver disease, or MASLD.
Despite the complicated name, MASLD is a type of liver disease that is caused by the same metabolic disturbances that have accompanied the rise of overweight and obesity coupled with inadequate physical activity. This is the same set of risk factors that have led to the increase in diabetes. So one can conceive of MASLD as the liver equivalent of diabetes.
Hepatis C, which is a blood-borne viral infection that can be acquired through injection drug use and needle sharing, is another important contributor to liver disease and cirrhosis.
Even though medical terminology has historically differentiated between alcohol and non-alcohol-related liver diseases, alcohol contributes to the progression of supposedly non-alcoholic liver disease, including MASLD and hepatitis C.
My colleagues and I studied patients with MASLD from the U.S.-based Framingham Heart Study. We found that even among non-heavy drinkers, there was a dose-dependent relationship between the amount of alcohol use and the severity of both liver inflammation and fibrosis.
Similarly, even low levels of alcohol use can hasten the development of liver cirrhosis among those with hepatitis C. For example, research has shown that in patients with hepatitis C, there is an 11 per cent increase in risk of cirrhosis with each one-drink increase in average drinks per day.
Preventing and reducing alcohol-caused harms to the liver
Beyond providing medical care for individual patients with known liver disease, steps need to be taken upstream within the health system. These include screening around alcohol use in primary care, counselling interventions for those with risky drinking habits and treatment for those with alcohol use disorders. To do this effectively, there needs to be more resources available for all of these interventions.
However, treating individuals does not address the larger public health issue: measures are needed to lower alcohol consumption at the population level.
This is a cornerstone of preventing and reducing liver disease and its resulting disability, hospitalizations and death. And the most effective way to reduce alcohol consumption is through alcohol control policies that:
- Make alcohol more expensive (for example, alcohol taxes and minimum prices);
- Less available (such as restrictions on hours of sale, or the number of locations that sell alcohol), or
- Less desirable socially (such as limits on advertising and marketing or sports sponsorships).
In previous research, we found that states with 10 per cent stronger or more restrictive alcohol policies had lower ALD mortality rates. Furthermore, states that increased restrictiveness by even five per cent showed subsequent reductions in ALD.
Liver harm caused by alcohol is a public health problem. Collectively, we need to take better care of our livers by taking steps to reduce alcohol consumption in the population.
