Abstract
Collagen is a protein with multiple roles within the human body, such as supporting fibroblast formation in the dermis, replacing dead skin cells, protecting organs, giving structure, strength and elasticity to the skin, and a primary role in blood clotting. The aim of the present study was to carry out an umbrella review with integrated meta-analyses to capture the breadth of health outcomes associated with collagen supplementation intake. This umbrella review of systematic reviews includes a search of the use of collagen in PubMed, Embase, Scopus, and Web of Science until March 2025. The effect size for each health outcome was calculated using standardized mean differences, relative risks, or odds ratios, along with their corresponding 95% CIs. Separate meta-analyses were conducted for each outcome and pooled effect sizes were calculated using the inverse variance method under a random-effects model. Meta-regression analyses were conducted to explore potential sources of heterogeneity, and the grading of evidence was carried out using the GRADE. Among 573 papers, 16 systematic reviews for a total of 113 RCTs and 7983 patients were included. In relation to skin, musculoskeletal health, and osteoarthritis conditions, collagen supplementation was consistently associated with favorable outcomes. Regarding oral health and cardiometabolic parameters, the impact of collagen supplementation yielded mixed results. Collagen supplementation demonstrates consistent and clinically meaningful benefits for dermal, bone, and muscular health. Level of Evidence: 3 (Therapeutic).