The effects of Ramadan intermittent fasting on liver function in healthy adults: A systematic review, meta-analysis, and meta-regression

Growing evidence is suggestive that intermittent fasting likely to improve liver function; however, still the evidences are controversial to draw a definitive conclusion. Therefore, we conducted a systematic review and meta-analysis to estimate the effect size for changes in liver function tests (LFT) in healthy people practicing Ramadan diurnal intermittent fasting (RDIF), and to examine the impact of different covariates using subgroup analysis and meta-regression. Scientific databases were searched from date of inception in 1950 to the end of July 2020. The liver function tests searched and analyzed were aspartate transaminase (AST), alanine transaminase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), bilirubin (BLU), L-lactate dehydrogenase (LDH) and prothrombin time (PT). Twenty studies (601 adult participants in total, aged 18–57 years) conducted in 10 countries between 1987 and 2020 were identified. RDIF-induced effect sizes for the LFT expressed as standardized mean difference (SMD) [95% confidence interval] were: AST (no. of studies K = 16, number of subjects N = 502, SMD = −0.257 [−0.381, −0.133], I2 = 42%); ALT (K = 16, N = 502, SMD = −0.105 [−0.282, 0.07], I2 = 71%); GGT (K = 2, N = 46, SMD = −0.533 [−0.842, −0.224], I2 = 0%); ALP (K = 10, N = 312, SMD = −0.318 [−0.432, −0.204], I2 = 0.0%); BLU (K = 10, N = 325, SMD = −0.264 [−0.520, −0.007], I2 = 70.1%); LDH (K = 5, N = 145, SMD = −0.041 [−0.380, 0.298], I2 = 72%); PT (K = 2, N = 74, SMD = −0.027 [−0.732, 0.678], I2 = 87%). RDIF induces significant but small (AST, ALP, BLU) to medium (GGT) positive changes on LFT, and may confer a transient, short-term protection against fatty liver disease in healthy subjects.