A recent University of California at Riverside study found that secondhand smoke from tobacco can lead to nonalcoholic fatty liver disease (NAFLD), which can cause fat to accumulate in the liver of people even if they drink moderately or don't drink alcohol at all.

Researchers studied mice exposed to secondhand smoke for a year and found that fat accumulated in their liver cells, a sign of NAFLD.

The researchers focused their attention on two main fat metabolism regulators that are also found in human cells:  the protein that stimulates synthesis of fatty acids in the liver and AMPK (adenosine monophosphate kinase), which regulates that protein.  They found that AMPK activity is inhibited when exposed to secondhand smoke, leading the other protein to synthesize more fatty acids. The result is NAFLD, according to the report.

"Our study provides compelling experimental evidence in support of tobacco smoke exposure playing a major role in NAFLD development," said Manuela Martins-Green, who led the study.

The study was published in the September 2009 issue of the Journal of Hepatology.