Patterns of Nutritional Supplement Use in Turkish Handball Players: Influence of Sex and Competition Level Based on the AIS Classification System

Handball is a sport that demands explosive movements and unique skills, and its popularity has been rising in recent years. This study evaluated elite handball players’ nutritional supplement (NS) use profiles and the differences in sex, competition level, and competition type based on the Australian Institute of Sport (AIS) criteria. The data collection form contains questions about participants’ sociodemographic characteristics, training details, use of supplements, and related factors. Supplements were classified into A, B, C, and D classes according to the scientific evidence level of the AIS. The study involved 92 elite handball athletes, comprising 48 professionals and 44 amateurs, and included 37 females and 55 males. The most frequently used supplements among participants were magnesium (37.0%) (Group C—AIS), vitamin C (20.7%) (Group B—AIS), whey protein (19.6%), sports bars (19.6%), and vitamin D (19.6%) (Group A—AIS). Regarding sex differences, a significant difference was observed only in Group C supplements, with male players using them more frequently than female players (p < 0.05). Professional athletes exhibited a significantly higher prevalence of supplement use, covering total, Group A, sports foods, performance supplements, and Groups B and C, relative to amateur players (p < 0.05). The results reveal that handball players have limited awareness of NS, emphasizing the need for training and consulting services.