Clinical studies and meta-analysis on the effects of collagen, vitamin, and nutrient supplementation for the rejuvenation of collagenic fibers: a systematic review

Abstract

Introduction: Collagen prevails in connective tissues, constituting 80% of the dry weight of human skin. Aging induces a decline in enzymes involved in the post-translational processing of collagen, reducing the number of fibroblasts that synthesize collagen and the vessels that irrigate the skin. Oral ingestion of hydrolyzed collagen together with vitamins and nutrients (especially apple exosomes) increases the levels of collagenderived peptides in the bloodstream and improves skin properties. Objective: It was to carry out a systematic review to elucidate the main results of clinical studies and meta-analyses of clinical studies on the effects of supplementation of types of collagen, vitamins, and nutrients for the rejuvenation of collagen fibers. Methods: The search was carried out from October to December 2023 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 122 articles were found, and 12 articles were evaluated in full, and 07 were included and developed in the present systematic review study. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 20 studies with a high risk of bias and 26 studies that did not meet GRADE and AMSTAR-2. Most studies showed homogeneity in their results, with X2=62.4%>50%. Oral nutritional supplements containing collagen peptides can reduce skin vulnerability in the elderly and thus prevent conditions such as skin lesions. The direct effects of collagen peptides on fibroblasts, M2-like macrophages, and mechanisms related to oral tolerance are the possible mechanisms for the beneficial effects of collagen supplementation. Special collagen peptides together with acerola extract, vitamin C, vitamin E, biotin, and zinc showed a significant improvement in the skin's collagen structure. The proven positive nutritional effect on collagen structure was fully consistent with the quality of healthy skin. Finally, apple-derived nanovesicles (exosomes) also reduce the degradation of the extracellular matrix, increasing collagen synthesis (COL3A1, COL1A2, COL8A1, and COL6A1) and negatively regulating the production of metalloproteinases.