Women with irregular periods may have a greater risk of developing non-alcoholic fatty liver disease (NAFLD).

An international study, co-funded by the Southampton NIHR Biomedical Research Centre (BRC), has identified the link for the first time.

The results show that women with long or irregular menstrual cycles may need greater advice to reduce risk through a healthy lifestyle.

NAFLD is the term for a range of conditions caused by a build-up of fat in the liver. It's usually seen in people who are overweight or obese, and is estimated to affect around 25% of the world’s population.

In the early stages many people are unaware they have it. However, if it progresses to the later stages the liver becomes so damaged it stops working properly and treatment options are limited.

It is therefore important to identify who is most at risk before it develops, or during the early stages of the disease, when lifestyle changes such as healthy eating and exercise are most effective.

First to find link with periods

Women with long or irregular periods are known to have a higher risk of type 2 diabetes and heart disease, but researchers found these women may also be at risk for NAFLD.

The researchers studied data on 72,092 women under 40 years old. About 28% of these women had long or irregular menstrual cycles, and 7% had NAFLD at the start of the study. The researchers followed up four years later and found new cases of NAFLD occurred in almost 9% of the women.

The researchers concluded that there was an association between long or irregular menstrual cycles in young, premenopausal women and an increased risk of NAFLD. They found this link was not explained by obesity.

Prof Christopher Byrne from NIHR Southampton BRC worked on the study with Professors Yoosoo Chang and Seungho Ryu from Sungkyunkwan University in Seoul, South Korea, and Prof Sarah Wild from the University of Edinburgh. The study was led by Profs Ryu and Chang.

They have published their findings in The Journal of Clinical Endocrinology and Metabolismexternal link.

Prof Byrne, Professor of Endocrinology and Metabolism, Honorary Consultant Diabetologist & Metabolic Physician, said:

“It is becoming clear that NAFLD is a multisystem disease that has effects beyond the liver. This work provides evidence that there is an association between metabolic liver disease and irregular periods.

“Whether there is a causal link between NAFLD and irregular menstrual cycles is uncertain but we are undertaking further research to understand whether the effects of NAFLD differ according to menopausal status.”

The study received funding from Sungkyunkwan University and the NIHR Southampton BRC.