Relationship between jet lag and obesity for liver cancer

Posted Nov 29, 2016 by Tim Sandle
Cases of liver cancer linked to obesity have risen in recent decades. This has prompted a research inquiry into the causes for this. The research has centered on obesity and jet lag.
Mallinaltzin (CC BY 3.0)
The research was triggered by scientists trying to understand why, since 1980, incidences of hepatocellular carcinoma (a common type of liver cancer) close to tripled. The primary cause for this has long been established as obesity. However, other life-style factors may also contribute.
To explore the various factors, researchers have run a series of mouse models. These studies simulated the effects of jet lag, by varying the sleeping, waking, eating and activity patterns of mice. The outcome was that excessive jet lag may also be a contributor to the risk of a person developing liver cancer.
The mouse model showed that normal weight mice, who were fed a healthy diet, went onto gain weight and fat, and also developed fatty liver disease, when exposed to the variations of simulated jet-lag. In some cases, the mice developed chronic inflammation and there were some cases of liver cancer.
An increased production of bile acids could be a contributor. This was shown through some control studies that used mice with the gene regulators that controlled the production of bile acid either enhanced or suppressed.
The study was performed by biologists from Baylor College of Medicine, in a team led by Professor David Moore. The reason for the higher chance of cancer, Dr. Moore explains, is due to the disruption of circadian rhythms. Such a disruption can occur with jet lag and also with some types of shift-work, such as those working night-shifts.
Physiologically, when people are exposed to light their bodies' central circadian clock, located in the brain, in the brain resets. Some activities, like flying through multiple time zones, significantly disrupts the clock. Given that the internal body clock controls many physiological functions, sometimes the body’s processes end up going awry.
Of course the research does not mean people who fly regularly will develop liver cancer. First, animal studies do not necessarily translate to people; secondly, the risks of developing liver cancer will relate to a range of physiological and genetic factors. Nevertheless, the results and the findings indicate that this subject requires further investigation. If the results are confirmed, then the use of a drug to control bile acid production for frequent flyers might be therapeutic solution.
The findings have been reported to the journal Cancer Cell, in a paper titled “Circadian Homeostasis of Liver Metabolism Suppresses Hepatocarcinogenesis.”