Obesity and alcohol act together to increase the risk of liver disease in both men and women according to two studies published on bmj.com today. These findings have significant clinical and public health implications.

In the UK, rates of liver disease and obesity are increasing. Alcohol is a major cause of liver cirrhosis. In addition, recent evidence indicates that excess body weight may also play a role.

Researchers from the University of Oxford examined in the first study the link between body mass index (BMI) and liver cirrhosis. A total of 1.2 million middle-aged UK women took part in the Million Women Study.

Each participant was monitored for an average of 6.2 years. Risks were modified according to age, alcohol consumption, smoking, socioeconomic status and physical activity.

Women who were overweight or obese had an increased relative risk of liver cirrhosis compared to women of a healthy weight. This relative risk did not differ considerably by alcohol consumption, but the absolute risk did.

For instance, among women who reported drinking an average of about a third to half a drink a day, 0.8 in 1,000 will be admitted to hospital with, or will die from, liver cirrhosis over five years if they are of healthy weight. This compares with 1 in 1,000 women who are obese.

However, among women who reported drinking an average of two and a half drinks a day, 2.7 in 1,000 will be admitted to hospital with or will die from liver cirrhosis over five years if they are of healthy weight. This compares with 5 in 1,000 women who are obese.

Researchers from the Universities of Glasgow and Bristol investigated in the second study the joint effects of BMI and alcohol consumption on liver disease in more than 9,000 men in Scotland. Participants were monitored for an average of 29 years.

Both factors were related to liver disease. Significantly, the combination of high BMI and alcohol consumption was greater than the additive effect of the two separate factors.

For instance, obese men who reported drinking 15 or more units per week had the greatest risk of liver disease: almost 19 times higher than underweight or normal weight non-drinkers. The researchers observe that lower, BMI specific “safe” limits of alcohol consumption may need to be defined for people who are overweight. They explain that in addition preventive efforts are required to limit the affordability and availability of alcohol and to increase physical activity.

From a public health standpoint, both studies conclude that strategies to reduce both excessive alcohol consumption and excessive body weight should result in a decline in the prevalence of liver disease.

In an associated editorial, Professor Christopher Byrne at the University of Southampton and Dr Sarah Wild from the University of Edinburgh comment that upcoming research must center on improved diagnosis and treatment of non-alcoholic fatty liver disease. This is a build-up of fat in the liver caused by obesity, high alcohol intake and diabetes and which can lead to cirrhosis.

They write that, for now, the old proverb of “prevention is better than cure” remains relevant. “Reducing alcohol consumption and obesity are, at present, our only weapons against non-viral liver disease. The progression of non-alcoholic fatty liver disease to end stage liver disease can now be added to the list of the undesirable consequences of modern lifestyles.”

“Body mass index and risk of liver cirrhosis in middle aged women in UK: prospective study”
Bette Liu, senior research fellow, Angela Balkwill, statistical programmer, Gillian Reeves, statistical epidemiologist, Valerie Beral, professor of epidemiology on behalf of the Million Women Study Collaborators
BMJ 2010; 340:c912
doi:10.1136/bmj.c912

“Effect of body mass index and alcohol consumption on liver disease: analysis of data from two prospective cohort studies”
Carole L Hart, research fellow, David S Morrison, clinical senior lecturer in cancer epidemiology, G David Batty, Wellcome trust fellow, Richard J Mitchell, professor of health and environment, George Davey Smith, professor of clinical epidemiology
BMJ 2010; 340:c1240
doi:10.1136/bmj.c1240

“Body fat and increased risk of cirrhosis”
Christopher D Byrne, professor of endocrinology and metabolism, S H Wild, reader in epidemiology and public health
BMJ 2010;340:c774
bmj.com

Written by Stephanie Brunner (B.A.)