A study by researchers at Oxford Population Health has found that people who walk more each day have a much lower risk of developing non-alcoholic fatty liver disease (NAFLD) ‒ a build-up of fat in the liver that is not caused by drinking.
NAFLD is the most common cause of chronic liver diseases, and a leading cause of cirrhosis and liver failure. It is predicted to be the most common reason for liver transplantation over the next decade.
The research, published in Medicine & Science in Sports & Exercise, aimed to address uncertainties in the relationship between physical activity and NAFLD risk, particularly due to previous reliance on self-reported activity measures. It is the biggest study to date to investigate the association.
To provide a more accurate assessment of participants' physical activity levels, the researchers used data from over 91,000 participants in the UK Biobank who wore wrist-worn devices over a seven-day period. Hospital records, death certificates, and imaging scans were used to see who developed NAFLD over a median follow-up period of nearly eight years.
The study had three key findings:
- People with higher step counts had a lower risk of developing NAFLD. This link is even stronger than suggested in earlier studies. Every 1,000-steps higher (representing 10 minutes of walking) was associated with a 12% lower risk of NAFLD.
- The association between higher step counts and lower NAFLD risk remained even when other factors like body mass index (BMI), high blood pressure, medication use, and diabetes were taken into account. However, these factors do explain part of the relationship.
- When using MRI scans (a more precise test) to measure NAFLD, the link between step count and NAFLD risk was only about half as strong. Every 1,000-steps higher was associated with a 6% lower risk of NAFLD.
Aiden Doherty, Professor of Biomedical Informatics and Wellcome Senior Research Fellow at Oxford Population Health, and senior author of the study, said ‘Our research shows that physical activity might be much more important than previously thought for the prevention of non-alcoholic fatty liver disease. These new findings critically rely on the world’s brightest minds working on large, secure medical research datasets. I would therefore like to thank the UK Biobank participants and team for data, and also MSc teaching staff at Oxford for training Evelynne Fulda to help conduct this exciting new epidemiological research.’
Evelynne S. Fulda, a DPhil student in Biomedical Sciences at Oxford Population Health, and lead author of the study said ‘Our study found that the more steps people take each day, the lower their risk of getting non-alcoholic fatty liver disease (NAFLD), and this drop in risk is much stronger than other studies have shown before. We also found that risk keeps going down in a steady, predictable way for people who are even more active. Previous studies had found a link between walking more and lower NAFLD risk, but our results show this connection is at least twice as strong as what was reported before.’
The researchers recognise that increasing step count may not be feasible or practical for some individuals. However, the findings are widely understandable and, in most cases, affordable to implement.
The work was undertaken as part of the lead author’s dissertation for the MSc in Global Health Science and Epidemiology. Evelynne Fulda is continuing her research at Oxford Population Health through the National Institutes of Health (NIH) Oxford-Cambridge Scholars Program. Read more about Evelynne's career.