Nutritional supplements (the combination of dietary supplements, sports foods, and performance-enhancing supplements) are used by many athletes for health and/or performance-related reasons. Nutritional supplements may be contaminated with illegal substances, putting the athlete at risk of adverse health outcomes or a positive doping test. Third-party testing programs help mitigate risk by regulating the purity and safety of supplements. However, it is unknown what percentage of high school athletes are familiar with third-party testing programs and how many athletes use such programs. This study was designed to explore high school athletes’ use of nutritional supplements, whether they were third-party tested, and their attitudes and influences toward safe(r) nutritional supplement use. An online questionnaire was developed to distribute among student-athletes from a private high school in the western US, resulting in a representative sample (n=225). Ninety-four percent (n = 211) of the student-athlete population reported using at least one nutritional supplement within the past year, reporting six different supplements on average. Sports foods were used the most (87%), followed by dietary supplements (76%), and then supplements claiming to enhance performance (58%). The most frequently reported nutritional supplements were sports drinks (72%), vitamins (65%), sports bars (60%), protein powder (58%), recovery drinks (46%), and multivitamin/mineral supplements (40%). One-fourth of student-athletes reported consistent use of third-party tested supplements. Reasons for supplement use include gaining muscle (48%), improving health (46%), improving performance (44%), and losing or gaining weight (29%). Parents (45%) had the most influence on the athlete’s purchasing of supplements, followed by friends, teammates, or other family members (40%), the physician (30%), head sports coach (26%), strength and conditioning coach (25%), and athletic trainer (24%). The sports dietitian was checked by 8% of students as influential. The biggest gap in knowledge was where to find third-party tested supplements (22% knowledgeable) and where to order third-party tested supplements (25% knowledgeable). Based on the results, high school athletes would likely benefit from increased education regarding third-party testing programs and should increase their knowledge of where to find and purchase third-party tested supplements.

Nutritional supplement use by high school student athletes may pose risks of consuming prohibited or banned substances that can result in suspension of athletic participation. Currently, there is no peer-reviewed published data that exists on the use of supplements and use of third-party tested supplements for this population. When looking at supplement use, the Theory of Planned Behavior (TPB) can be utilized. This model was designed to determine if the intention of completing a behavior is based on three different constructs which include attitude, subjective norm, and perceived behavioral control. A pre- and post- test questionnaire was used to determine the effect of an educational intervention that was designed and developed. A total of 106 high school student athletes, ranging from 14-19 years of age from a private high school in the western US were included in the analysis of the study. The intention to use a good basic diet and intention to use nutritional supplements were both predicted by attitude, subjective norm, and perceived behavioral control and both resulted in a significant regression equation (p < .001). There was 95.3% (n=101) of athletes that reported use of at least one supplement in the last 12 months with reporting on average eight supplements ranging from 0-31 supplements. In conclusion, almost all high school student athletes reported using at least one nutritional supplement in the last 12 months, while roughly one-fourth consistently reported to use third-party tested nutritional supplements. The TPB based supplement education program resulted in the intention to change supplement behavior toward using safe third-party tested supplements more frequently at a group level.