Study highlights key determinants of dietary supplement use among varsity athletes

Led by PhD candidate Jana Daher under the supervision of Dr. Dalia El Khoury at the University of Guelph in Canada, the research provided insights that may inform future educational initiatives and industry practices.

“Our findings indicated that the online nutrition education program significantly improved varsity athletes’ intentions, attitudes and perceived behavioral control towards dietary supplement use,” Daher told NutraIngredients.

Background and study objectives

While varsity athletes are a significant demographic of dietary supplement users, their supplement use remains underresearched, Daher said.

“We believe that understanding the motivations and key determinants behind supplement use among athletes is crucial for developing effective interventions to influence and modify these behaviors,” she added.

Given the potential benefits and risks associated with supplement use, it is crucial to understand the factors that impact various athletes’ supplement choices, the authors wrote.

Specifically, athletes often rely on supplements to enhance performance, recovery or overall health. Yet, they may not always have access to accurate, evidence-based information, the authors noted, adding that “the prevalence of misinformation increases the risk of uninformed or potentially harmful choices.”

Study methodology

To develop the online education program content, the research team used the most recent available research evidence, Daher said.

Applying the Theory of Planned Behavior

As the study authors wrote, these objectives were based on the normative, behavioral and control beliefs proposed by the Theory of Planned Behavior.

Daher explained that the theory “served as the conceptual framework to design our intervention,” emphasizing “the role of three constructs—attitudes, subjective norms and perceived behavioral control—in shaping an individual’s intentions to perform a certain behavior.”

For example, she said that the researchers aimed to positively influence the athletes’ attitudes towards dietary supplementation “by providing evidence-based information about the actual benefits and risks of supplements, while also addressing misconceptions.”

Findings: Shaping attitudes and intentions

Daher said that the program “decreased participants’ positive attitudes towards the ability of dietary supplements to improve performance or health,” and “strengthened their perception of their ability to control the decision to use or not use dietary supplements.”

These insights offer a valuable foundation for developing educational materials by dietary supplement manufacturers and suppliers.

“Our results suggest that athletes are more likely to make informed decisions about supplement use when provided with evidence-based information,” Daher said.

“Manufacturers and suppliers could benefit from developing educational materials that challenge misconceptions and highlight the importance of informed decision-making.”

Challenges and future directions

One limitation of the online program was the participants’ inability to ask real-time questions. To address this challenge, the researchers purposely designed the program’s content to be written in language that was clear and easy to understand for greater participant accessibility, Daher said.

An external OpenEd team also reviewed the program, she added, “who are not experts in the field, to ensure that the material was comprehensible to a wider audience.”

“Future research could benefit from recruiting a more diverse participant pool to explore potential characteristic-based differences, such as variations in the intervention’s impact based on age, sex and sports team.”

Industry collaboration for responsible supplement use

The study highlighted opportunities for collaboration to promote informed supplement use.

“Manufacturers and suppliers can play a crucial role in promoting responsible supplement use by collaborating with researchers to create evidence-based educational materials,” Daher said.

“They can work with academic institutions and experts in the field to ensure that the information they provide to athletes is accurate, up-to-date, and free from marketing bias.”

Daher also pointed to the role of industry in supporting research initiatives.

“Manufacturers can support research by funding studies that assess the efficacy and safety of supplements in athletic contexts and work with researchers to disseminate findings that promote a more balanced, fact-driven approach to supplement use,” she said.

This research was funded by the Seeding Funding Grant by the College of Social and Applied Human Sciences at the University of Guelph.

Source: Nutrients, 2025, 17, 557. doi: 10.3390/nu17030557, “An Online Nutrition Education Program Targeting Intentions and Related Determinants Towards Dietary Supplement Use: An Application of the Theory of Planned Behavior.” Authors: Daher, J.; Mountjoy, M.; El Khoury, D.