Maintaining safe limits of alcohol intake can mean different things, as females are more susceptible to liver injury at much lower doses than their male counterparts and, as a result, may suffer more extensive liver disease if they drink the same amount as a man.

Researchers at the University of Pittsburgh School of Medicine and the Veterans Affairs Medical Center used animal models to analyze the differences in liver injury between the sexes due to chronic alcohol ingestion, using two diets that vary in carbohydrate and fatty acid content. One diet contained fish oil, while the other contained a mixture of vegetable oils. They reported their findings at the Digestive Disease Week conference held in Chicago.

Alcohol-induced liver injury (ALI) can involve damage that ranges from mild to quite severe: fatty liver (fat buildup in liver cells), alcoholic hepatitis (an inflammatory condition) or cirrhosis (replacement of normal tissue with fibrous scar tissue).

Male and female rats were divided into groups and given either no alcohol (IC) or alcohol (AF) in a higher-carbohydrate diet (LDC) or a low-carb, higher-fat diet (NFO) for eight weeks. Researchers determined injury to the intestine by measuring bacterial translocation and blood endotoxin levels, and also the degree of liver injury. Previous reports have shown that endotoxins, which are bacterial products that can escape from the intestine, appear to be a major factor in the development of ALI.

Female rats fed alcohol in the high-fat fish oil (NFO) diet had significantly greater bacterial translocation (escape of bacteria from the gastrointestinal tract to abdominal lymph nodes, in this example), higher blood endotoxin levels and more severe liver injury than male rats on the same diet or rats of either sex on the LDC diet (2-fold increase in total change), based on their intake of unsaturated fatty acids and alcohol.

These results indicate that the intestines of the females had become permeable as a result of the alcohol-fish oil combination in the diet.

All rats that ingested alcohol demonstrated some degree of fatty change in their livers, but liver inflammation was evident only in females fed the NFO diet, and both female and male rats on the LDC diet showed fatty liver only, without bacterial translocation or elevation of endotoxin levels.

"Our research suggests that women should be cautious about the amount of alcohol they consume, since they are highly susceptible to more severe liver injury than men and thus to potentially serious complications," said Patricia Eagon, Ph.D., of the University of Pittsburgh and Pittsburgh VA Medical Center and lead author of the study. "Our work also shows that in females, alcohol in the diet along with fish oil injures the intestine, which causes release of factors that contribute to liver injury."