Mitochondrial DNA 5178 C/A polymorphism modulates the effects of coffee consumption on elevated levels of serum liver enzymes in male Japanese health check-up examinees: an exploratory cross-sectional study

BACKGROUND: Longevity-associated mitochondrial DNA 5178 cytosine/adenine (Mt5178 C/A) polymorphism modulates the effects of coffee consumption on the risk of hypertension, dyslipidemia, and abnormal glucose tolerance. The objective of this study was to investigate whether Mt5178 C/A polymorphism modifies the effects of coffee consumption on abnormally elevated levels of serum liver enzymes in male Japanese health check-up examinees. METHODS: A total of 421 male subjects (mean age ± SD, 54.1 ± 7.7 years) were selected from among individuals visiting the hospital for regular medical check-ups. After Mt5178 C/A genotyping, a cross-sectional study assessing the joint effects of Mt5178 C/A polymorphism and coffee consumption on elevated levels of serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), and serum gamma-glutamyl transpeptidase (GGT) was then conducted. RESULTS: For men with Mt5178C, after adjustment for age, body mass index, alcohol consumption, habitual smoking, green tea consumption, antihypertensive treatment, and antidiabetic treatment, elevated levels of serum AST, as defined as ≥30 U/L; those of serum ALT, as defined as ≥25 U/L; or those of serum GGT, as defined as ≥60 or >51 U/L, may depend on coffee consumption (P for trend = 0.013, P for trend <0.001, P for trend = 0.002, and P for trend <0.001, respectively). On the other hand, no significant joint effects of Mt5178A genotype and coffee consumption on elevated levels of serum liver enzymes were observed. CONCLUSIONS: The present results suggest that Mt5178 C/A polymorphism modifies the effects of coffee consumption on abnormally elevated levels of serum liver enzymes in male Japanese health check-up examinees.