The impact of food restriction on liver enzyme levels: a systematic review and meta-analysis

Context The relationship between food restriction (FR) and liver enzyme levels, such as alanine transferase (ALT), aspartate transferase (AST), and gamma-glutamyl transferase (GGT), has not yet been confirmed. Objective A meta-analysis of research articles was conducted to investigate the association of FR and liver enzyme levels. Data sources The PubMed, Web of Science, Embase, and Cochrane Library databases were screened for articles published up to April 30, 2022. Data extraction Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement methodology was used to search for research articles. Publication bias was detected using Begg's test. Finally, 17 trials involving 1982 participants and that reported mean value, mean difference, and standard deviation were identified. Data analysis Data were described as the weighted mean difference of body mass index, body weight, and standardized mean difference (SMD) of ALT, AST, and GGT. A reduction in ALT level was observed after a FR intervention (total SMD, -0.36, 95% confidence interval [CI], -0.68 to -0.05). GGT levels also were decreased in 4 studies (total SMD, -0.23; 95%CI, -0.33 to -0.14). According to subgroup analysis, serum AST levels decreased in the medium-term (between 5 wk and 6 mo) group (subtotal SMD, -0.48; 95%CI, -0.69 to -0.28). Conclusion Existing evidence suggests that dietary restriction improves adult liver enzyme levels. The long-term maintenance of healthy liver enzyme levels, particularly in real-world applications, necessitates additional consideration.