Background: Professional soccer players are advised to consume 3-8 g kg-1 body mass day-1 of carbohydrate (CHO) on the basis of training demands, fixture schedule and personal objectives. However, owing to the lack of randomized controlled trials on elite players, these guidelines largely rely on data interpretation and practitioner experience. Objective: To identify the gaps in existing literature that inform CHO guidelines for soccer players. Methods: A scoping review was conducted without date restrictions up to 21 March 2024, employing a three-step search strategy to identify relevant English-language primary and secondary articles through PubMed and reference searching. Data were extracted using a standardized audit tool from studies assessing direct and indirect impacts of CHO on soccer players` performance and health. Results: Within 258 studies identified, experimental studies were the most common (~ 36%), followed by observational (~ 33%) and narrative reviews (~ 26%), with systematic reviews, meta-analyses and case studies making up the rest (~ 5%). Most observational studies were field-based (~ 98%), while experimental studies were laboratory-based (~ 75%). Among 4475 participants, ~ 16% were female, and only ~ 12% of the original research was exclusively conducted on female players. Observational studies included developmental (~ 52%) and professional players (~ 31%), whereas experimental studies primarily featured recreationally active (~ 40%) and collegiate/university participants (~ 26%). Key research topics were `dietary intake` (~ 52%) and "energy expenditure and dietary intake" (~ 30%) for observational studies and `CHO interventions` (~ 74%) for experimental studies. Only eight experimental studies exclusively involved professional players, focusing on CHO intervention (n = 7) and CHO co-ingestion (n = 1). Narrative reviews were published in journals with higher impact factor (4.1 ± 6.4) than were observational studies (3.2 ± 1.6, p < 0.001) and experimental studies (3.4 ± 1.6, p < 0.001). Narrative reviews had the most studies, with Altmetric scores = 20 (n = 26), followed by experimental (n = 16) and observational studies (n = 14). Conclusions: Current CHO guidelines for elite soccer players lack experimental research specific to professional and world-class players. More field-based experimental trials involving elite soccer players are required to ensure evidence-based CHO recommendations. Key Points 1. This scoping review and audit of carbohydrate research for soccer shows a predominance of laboratory-based experimental studies and field-based observational studies, while the scarcity of field-based experimental trials involving professional and world-class soccer players highlights the need for such research to enhance the translational applicability of carbohydrate guidelines for this population. 2. Narrative reviews occupied a significant space in the carbohydrate literature for soccer and tended to be published in higher impact factor journals and receive more Altmetric attention compared with original research; therefore, this trend may incentivize researchers to publish reviews over original studies, potentially slowing progress in advancing practical, evidence-based carbohydrate guidelines in soccer. 3. Female soccer players are notably underrepresented in carbohydrate research, resulting in current Union of European Football Associations (UEFA) nutrition guidelines for females being largely extrapolated from male-focused data; this emphasizes the urgent need for targeted, evidence-based studies to inform sex-specific nutritional guidelines for female soccer players.
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