Knowledge, attitudes and practices of gym users towards the use of dietary supplements–A systematic review

Dietary supplements (DS) are products that are taken alongside the usual diet and utilized to attain a particular health result or enhance exercise performance. DS are increasingly popular among the general population, including gym users without sufficient knowledge. This systematic review aims to understand the sources of knowledge, reasons for supplement usage, and practices of DS usage among gym users. A systematic search in PubMed, Web of Science, and Scopus was performed to identify the cross-sectional survey-based studies, published between 2013 and 2023, related to knowledge, attitudes, and practice of DS use among gym users. The risk of bias was assessed using the Risk of Bias Instrument for Cross-Sectional Surveys of Attitudes and Practices. A total of 24 eligible studies were included in this review. These studies were conducted in: Africa (n = 3), Asia (n = 6), Europe (n = 6), and South America (n = 1). Participants in the included studies were gym users (n = 9202) with the total supplement users being (n = 5370). Results showed that there is a high prevalence of supplement usage among gym users, the internet and media were the most used sources of information, healthcare improvement is the most reported reason for supplement usage, and protein supplements are the most used type of supplements. These findings suggest that there should be more attention to sources of information on the use of dietary supplements with the finding of a high prevalence of dietary supplement usage accompanied by the prevalent use of non-trustworthy sources of information, such as the internet, media and non-healthcare professionals.