Alcohol is readily absorbed from the digestive tract, and up to 98% is metabolised in the liver. Each liver cell contains three pathways for alcohol metabolism. All of these result in the production of a highly toxic metabolite which can contribute to liver cell damage.
Reversible injury of liver cells can occur with large quantities of alcohol. With regular alcohol use, this regenerative ability may be inhibited and lead to sustained liver damage. Long term heavy alcohol use may lead to fat accumulation in the liver, which may progress to alcoholic hepatitis, or to liver cirrhosis.
Recommended Safe Levels:-
The Australian National Health and Medical Research Council (NH&MRC) has provided guidelines for safe daily drinking limits. The recommended maximum for men is 4 standard drinks per day. For women it is 2 standard drinks per day.
One standard drink contains 10 grams of alcohol, and is equivalent to one ordinary beer, a small glass of wine (100 mls) or a nip of spirits (30 mls).
More than 6 standard drinks per day for men, and 4 standard drinks for women, is known to cause harm. Long term effects of alcohol on the liver as identified by the NH&MRC include impaired liver functioning, severe pain, inflammation (hepatitis) and cirrhosis.
Are Women at Greater Risk?
As one of the Danish studies (listed below) indicated, gender is an important risk factor for alcohol-induced liver damage. It found that women have a significantly higher risk of developing alcohol-related liver disease than men for any given level of alcohol intake.
Tissue ethanol concentrations are higher in women, and with high regular intake of alcoholic beverages, severe hepatic damage can occur over a period of years. Depending on individual variations, significant liver disease may develop in 5 years, or 20. While prolonged daily intake of 80gms of alcohol may cause liver damage in men, in women 50gms may be harmful.
Some Study Findings –
- A study which determined the risk level for developing cirrhosis in Australian men who drank alcohol found the risk increased significantly when alcohol intake exceeded 40 grams per day. The risk for women was determined to occur at a similar intake level. 40 gms/day (4 standard drinks) was concluded to be the safe maximum level for both men and women. [Batey R et al Med J Aust (1992) 156 (6)].
- 1% of deaths for 1986 were examined in the U.S. Quantity and frequency of alcohol consumption was obtained from each descendant’s next of kin. The percentage of deceased with cirrhosis increased sharply with increasing number of drinks per day. An intake of three alcoholic drinks per day was associated with a significantly higher percentage of cirrhosis deaths compared with lifetime abstainers. [Parrish K et al, J Stud Alcohol (1993) 54(4)].
- 156 papers were reviewed assessing the relation of individual alcohol consumption to risk of physical damage. Evidence was found for a dose-response relationship between alcohol consumption and risk of liver damage. At levels of more than 20-30 grams alcohol/day, all individuals are likely to accumulate risk of harm. [P.Anderson et al. Addiction (1993) 88(11)].
- In a consecutive autopsy series of 210 Finnish males, the effects of long-term moderate alcohol consumption on the incidence of liver disease were observed. Below 40 gms of alcohol/day no significant increase in the features of liver disease were apparent. Daily intake of between 40 – 80 gms/day increased the frequency of fatty liver and slight alcoholic hepatitis. The incidence of liver cirrhosis increased significantly when daily intake exceeded 80gms. [V.Savolainen et al. Alcohol Clin Exp Res (1993) 17 (5)].
- A Danish study measured the prevalence of abnormal liver-derived enzymes in a population sample of 905 men and women aged 30-50. 12% of the cohort was found to have raised levels of abnormal liver-derived enzymes associated with moderate (48gms/day) alcohol intake. With higher alcohol intake (>48gms/day) the odds ratio for raised liver enzymes increased further. [F. Steffensen et al. Int J Epidemiology (1997) 26(1)].
- In another Danish study, self-assessed alcohol intake was determined in a prospective cohort study of 13,285 men and women (aged 30-79 years). The diagnosis of alcohol-induced liver disease was observed. An estimated relative risk of developing liver disease was determined at an intake of 1 – 6 alcoholic beverages per week, with a steep increase in risk above this intake. Women were found to have a significantly higher relative risk of developing alcohol-related liver disease than men. At 7-13 alcoholic beverages per week for women, and 14-27 for men, the relative risk of developing liver disease was greater than one. [U.Becker et al. Hepatology (1996) 23(5)].
- An Italian cohort study looked at the prevalence of chronic liver disease. 6534 subjects aged 12-65 were fully examined, and their alcohol intake evaluated with a dietary questionnaire. The risk threshold for developing liver damage was found at ingestion of more than 30gms alcohol/day (both sexes). 21% of the study group were at risk, and 5.5% of this risk group (74 individuals) showed signs of liver damage. Alcoholic cirrhosis was diagnosed in 2.2% of the risk group (ratio men:women, 9:1) and non-cirrhotic liver disease in 3.3%. The authors concluded that in an open population the risk threshold for developing cirrhosis and non-cirrhotic liver damage is 30gms ethanol per day. This risk increases with increased daily intake. [S.Bellentani et al. Gut (1997) 41(6)].