Background  The association between body-mass-index (BMI), alcohol consumption and their joint effect in increasing the risk of elevated serum alanine (ALT) and aspartate (AST) is unclear in older community-dwelling adults.

Aim  To determine the association between alcohol, BMI, and their combined effect with serum ALT and AST in older community-dwelling adults in the United States.

Methods  A cross-sectional, population-based study in participants (n = 2364) from the Rancho Bernardo Study (54% women; mean age: 70 years, BMI: 25 kg/m2, alcohol users: 63%) who attended a research visit in 1984–87. BMI was recorded by a trained nurse and alcohol use ascertained by a validated questionnaire. Odds-ratio (OR) and 95% confidence intervals (CI) of elevated serum ALT and AST (defined as ≥30 U/L in men and ≥19 U/L in women) were calculated for alcohol and BMI separately and their joint exposure using logistic regression models.

Results  In multivariate logistic regression models adjusted for age, alcohol use, total cholesterol, serum triglycerides, fasting plasma glucose, systolic blood pressure, and diabetes mellitus, obesity independently increased the odds of elevated ALT in this cohort of older men and women by 3.0 (95% CI, 1.7–5.3) and 1.8 (95% CI, 1.1–2.7) respectively. Joint effects of consuming >3 alcoholic drinks/day and obesity raised the odds of elevated ALT by 8.9 (95% CI, 2.4–33.1) and AST by 21-fold (95% CI, 2.6–170.1), demonstrating synergism. Obese participants had higher odds of elevated ALT even at 0 ≤ 1 drink/day.

Conclusions  In older men and women, the combination of obesity with alcohol is synergistic in increasing the risk of liver injury.