Effectiveness of low-fat diet on the levels of insulin-like growth factor-1 and insulin-like growth factor binding proteins: a systematic review and meta-analysis of randomized controlled clinical trials.

Background: Previous researches on the effect of low-fat diet (LF) on insulin-like growth factor-1 (IGF-1), and its binding proteins (IGFBPs) did not reach a consensus result, and there is no study summarizing these findings. Thus, this systematic review and meta-analysis of randomized control trials (RCTs) was performed to pool available evidence and answer the question whether dietary fat can affect IGF-1 and IGFBPs or not.

Methods: PubMed, Scopus, ISI Web of Science, Google, Google scholar, ProQuest, and the Cochrane Library were searched without language restrictions until July 2, 2024 to retrieve related studies. Weighted mean difference and the corresponding variance were considered as the effect size. Standard tools were applied to assess the quality of the studies and evidence.

Results: Pooling data of the eligible studies showed no significant effect of LF diet on IGF-1 (six studies; participants = 1029.; pooled mean = 1.63 ng/ml, 95% CI= [-1.34, 4.59], P = 0.28, I² = 0.00%), and IGFBP-3 (five studies; participants = 969; pooled mean = 65.24 ng/ml, 95% CI= [-169.53, 300.00], P = 0.59, I² = 0.0%). The results of subgroup analysis for IGF-1 and IGFBP-3 also demonstrated no significant findings. For IGFBP-1, available evidence is insufficient since only two studies have been performed yet and their results are contradictory.

Conclusions: This study indicated no significant effect of LF diet on IGF-1, and IGFBP-3 concentrations. Low certainty of evidence indicates that available evidence cannot support to draw a firm conclusion and future researches may change the estimates.