Abstract
BACKGROUND: This study investigated the nutritional knowledge and prevalence of dietary supplements (DSs) among Iranian bodybuilders. METHODS: This cross-sectional research study involved sampling 648 bodybuilding clubs in Iran. A researcher distributed questionnaires among clubs in various regions and analyzed categorical variables, DS, nutritional knowledge, and sports nutrition data from 160 bodybuilders aged 18 and above in Iran. The analysis was conducted using the results obtained from a quantitative questionnaire. RESULTS: There was a significant relationship between DS use and gender (P = 0.001, r = 0.330, males > females), bodybuilding history (P = 0.045; r = 0.158), and exercise sessions/wk (P = 0.050, r = 0.156). Whey protein (45.6%) and branched-chain amino acid (33.7%), vitamin D (50%), caffeine (34.3%), and generally vitamin C (56.2%) were the most common DS used. The most information sources for bodybuilders regarding DS were fitness coaches (35.6%) and registered dietitians/nutritionists (34.3%). Drug stores (36.7%) and fitness coaches (19.3%) were the most prominent sources for purchasing DS. Increasing performance (54.3%), increasing the need for DS through exercise (53.6%), preventing injury, and improving recovery (36.2%) were the most important reasons to consume DS. Skin problems (21.0%), increased liver enzymes (10.8%), and hair loss (9.4%) were the most common side effects of DS use. Total nutritional knowledge (macronutrients, micronutrients, and sports nutrition) was 58.6%. CONCLUSIONS: This study concluded that fitness coaches and registered dietitians/nutritionists were the most common information sources for bodybuilders. It also revealed a moderate level of nutrition knowledge among bodybuilders. The most commonly used DS were vitamins C, D, and whey protein. Also, gender, bodybuilding history, and exercise sessions had a significant relationship with the prevalence of DS. However, the study also revealed some concerning findings; bodybuilders commonly experienced adverse side effects such as skin rashes, increased liver enzymes, and hair loss.