Can coffee cause Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT) elevation?

Coffee's Effect on AST and ALT Levels

Coffee consumption does not cause AST and ALT elevation; rather, it appears to have a protective effect against liver enzyme elevation and may actually lower these enzymes. 1, 2

Relationship Between Coffee and Liver Enzymes

Protective Effects of Coffee

• Multiple clinical guidelines and research studies consistently show that coffee consumption is associated with lower, not higher, liver enzyme levels 2, 3
• Coffee drinking appears to have a beneficial impact on liver morphology and function 4
• Coffee consumption has been associated with:
  • Reduced risk of alcoholic liver disease (ALD) 1
  • Lower levels of AST and ALT in the general population 5
  • Decreased incidence of abnormal liver enzyme elevations 6

Evidence from Clinical Guidelines

• The European Association for the Study of Liver Disease (EASL) guidelines note that drinking up to two cups of coffee per day decreased the risk of alcoholic cirrhosis by nearly half (relative risk 0.62) 1
• The Korean Association for the Study of Liver Disease (KASL) guidelines state that many studies have found the risk of ALD reduces as coffee consumption increases 1
• The EASL-EASD-EASO guidelines on metabolic dysfunction-associated steatotic liver disease (MASLD) indicate that coffee consumption has been associated with improvements in liver damage 1

Research Evidence

• A 4-year follow-up study of middle-aged Japanese men showed that coffee drinking was independently and inversely associated with the development of elevated AST and/or ALT 6
• Analysis of the National Health and Nutrition Examination Survey (1999-2010) found that both caffeinated and decaffeinated coffee were associated with lower levels of liver enzymes 3
• In the Korean population, consumption of coffee ≥2 times/day was associated with significantly lower odds of elevated ALT (aOR=0.86) and AST (aOR=0.83) compared to those who drank <1 time/day 5

Mechanism of Protection

Coffee contains numerous bioactive compounds that may contribute to its hepatoprotective effects:

• Polyphenols and other antioxidants that may reduce oxidative stress in the liver 7
• Anti-inflammatory properties that could reduce liver inflammation 4
• Potential modulation of the glycemic response, which may contribute to reduced endogenous advanced glycation end products (AGE) accumulation 1

Clinical Implications

For General Population

• Coffee consumption appears safe and potentially beneficial for liver health
• No evidence suggests coffee causes AST or ALT elevation; rather, it may help maintain normal liver enzyme levels

For High-Risk Groups

• Coffee may be particularly beneficial for those at high risk for liver disease:
  • People with alcoholic liver disease 1
  • Individuals with HIV-HCV co-infection 7
  • Those with obesity or metabolic syndrome 5

Dosage Considerations

• Most studies show benefits with moderate coffee consumption (2-3 cups per day) 1
• Both caffeinated and decaffeinated coffee appear to have hepatoprotective effects 3

Common Pitfalls and Caveats

• Don't confuse coffee's effects with those of other beverages:
  • Sugar-sweetened beverages and high-fructose drinks may increase liver enzyme levels 1
  • Alcoholic beverages significantly increase risk of liver enzyme elevation 1, 2
• Coffee's protective effect doesn't override the harm from excessive alcohol consumption, which remains a primary cause of liver enzyme elevation 1, 2
• Individual responses may vary based on:
  • Genetic factors affecting caffeine metabolism
  • Pre-existing liver conditions
  • Consumption patterns and preparation methods

In conclusion, coffee consumption is not a cause for concern regarding AST and ALT elevation; current evidence suggests it may actually help maintain normal liver enzyme levels and potentially protect against liver disease.