"Our findings suggest that not only the quantity of alcohol intake, but also the way in which alcohol is consumed can be an important and independent determinant of liver disease risk," said Saverio Stranges, a research instructor in the department of social and preventive medicine at the State University of New York at Buffalo, and first author of the study. "Our findings also suggest that the effects of drinking patterns on potential liver damage vary by gender: women show a greater susceptibility in general; while for men, the amount and frequency of drinking seem to be very important."
Liver injury can be determined by testing the blood for concentrations of certain enzymes, such as gamma-glutamyltransferase (GGT), aspartate amino-transferase (AST), and alanine amino-transferase (ALT).
"ALT, AST and GGT are the most widely used biochemical indicators of liver function," said Stranges. "Although these enzymes are not very specific, they are used routinely for assessing liver function in health screening, and in epidemiological research that focuses on the risk factors for liver disease, including alcohol consumption. Among them, GGT, despite its lack of specificity, seems to be the hepatic biomarker most strongly associated to alcohol intake. Other factors, such as obesity and body fat distribution, appear to be stronger determinants for aminotransferase levels, especially for ALT."
Stranges and his colleagues examined 2,943 Caucasians (1,575 females, 1,368 males) from two counties in New York state, enrolled as part of a larger series of studies conducted between September 1995 and May 2001. All of the study participants were between the ages of 35 and 80 years, and were free from any known hepatic diseases. Computer-assisted in-person interviews gathered information about their alcohol intake, such as drinking frequency during the week, drinking with meals and snacks, drinking in the absence of food, and mixed. Blood samples from all study participants were measured for levels of GGT, AST, and ALT.
The most significant association was found with GGT: for both genders, average GGT levels were significantly higher in both current and former drinkers compared to lifetime abstainers.
"Our findings also suggest that how and when drinkers consume alcohol may be as important to a healthy liver as the amount consumed," said Stranges. "Moreover, these findings reveal gender differences in the effects of drinking on the liver. In men, the amount and frequency of drinking seem to be more important than pattern, while in women, pattern appears to be more important than the amount consumed. Specifically, we found that the men who drank daily had the highest levels of GGT; while in women, GGT levels were highest in those who drank only on weekends. A gender difference was also found when examining food intake.
Gender Differences in Metabolism"Women who did not eat or snack when they drank had higher levels of GGT than women who drank primarily with a meal, even though the amount of alcohol was the same. In men, there was no significant difference in GGT levels between those who drank with food and those who did not. Finally, and not surprisingly, the amount of alcohol men and women could consume without causing potential liver damage, based on GGT levels, also differed. Results showed that the safe range for men was 14 to 27 drinks per week, or [roughly] three a day; for women, the safe range was 7 to 14 drinks per week, or no more than two a day."[p Stranges noted that the apparent greater susceptibility to hepatic damage among women is most likely the result of differences in how men and women metabolize alcohol. The fact that women need to drink a lesser amount of alcohol than men, or for a shorter amount of time, to produce the same degree of damage is referred to as the "telescoping" phenomenon.
Some of the reasons behind this phenomenon, he said, include a decreased gastric oxidation of ethanol and lower gastric alcohol dehydrogenase activity in women, the interference of hormonal status (both endogenous and exogenous female hormones have been shown to result in some impairment of liver function in a significant number of women), methodological issues, such as a higher degree of underreporting of alcohol intake among women than men, and possibly other risk factors associated with specific drinking patterns.