Jet lag increases obesity-related liver disease and cancer

Disruptions to circadian rhythms have a greater health impact than previously thought.

A study published today in Cancer Cell has found a link between chronic jet lag and an increase in both obesity-related liver disease and a higher risk of liver cancer in mice.

Researchers at Baylor College of Medicine and Florida State University used light to simulate two different time zones, regularly shifting mice between them and disrupting their circadian rhythms. The study found that, despite being fed a healthy diet, the mice still gained weight and were more likely to develop fatty liver disease than mice who had healthy sleep patterns. In some cases, this fatty liver disease then progressed into liver cancer.

The jet-lagged mice were also found to lose control of their liver metabolism,  increasing their production of bile acids. The researchers explained that these acids act as a kind of detergent to absorb foods that are rich in fats, however previous studies have found that high bile levels are linked to an increased risk of liver cancer in humans. As a next step in the study, the researchers are looking for solutions and will examine whether drugs could negate the effect jet lag has on bile acid levels.

"Recent studies have shown that more than 80 percent of the population in the United States adopt a lifestyle that leads to chronic disruption in their sleep schedules. This has also reached an epidemic level in other developed countries, which is coupled with the increase in obesity and liver cancer risk," says Dr Loning Fu, co-senior author of the study.

The researchers hope their study will raise awareness of the significant health impact disrupted sleep, particularly altered circadian levels, can have on people.

"This experiment allowed us to take several threads that were already there and put them together to come to this conclusion," says the study's second senior  author, Professor David Moore. "We think most people would be surprised to hear that chronic jet lag was sufficient to induce liver cancer."

Image credit Giulia Mule.