Summary of findings
This study aimed to explore the frequency of, and reasons for, DS use, and the frequency of, and explanatory factors for use of MEDS specifically, in male and female university students.
Among Norwegian university students, a similar frequency of males (42.3%) and females (39.5%) reported use of DS. Most students reported to maintain health, improve physical or mental performance, and to increase muscle mass, as reasons for DS use in general. As many as 1 in 4 males and 1 in 10 females used MEDS, with a significant gender difference. In males, being a fitness center member, exercising to improve muscle mass, and a higher physical activity level, positively explained use of MEDS, while exercising to increase endurance and being an exercise science student, negatively explained use of MEDS. In females, internalizing the athletic body ideal and exercising to improve muscle mass positively explained use of MEDS.
Frequency of dietary supplement and muscle enhancing dietary supplement use
The frequency of DS and MEDS use in our sample is lower than previously reported [2, 5, 7,8,9]. Differences in BMI seem not to be explaining these differences, as BMI in the current sample is comparable to previous student samples [2, 5, 13, 35]. The differences in use of DS in general, and MEDS in particular, when comparing to other studies, might have been influenced by how “use” was defined, in which our study asked about “current use”, while previous studies asked about “the last six months” [2, 7, 8] or “the past 12 months” [9]. Our results indicate a low frequency of use of illegal DS (0.3% in both genders), which is lower than previous findings among Norwegian males (2.9%) and females (1.0%) trying out for the military basic training [38].
The lack of gender difference in use of DS in general, echoes what most studies from other countries have found [5, 6, 11, 13, 14]. However, our study is among few which have investigated gender differences for specific supplements, such as MEDS, and strengthens the assumption that males are more likely to use MEDS than females [5, 8, 11]. This gender difference might reflect a variance in advertisement targeted at males and females [39]. It could also reflect a more prolonged period of muscular body idealization within the history of masculinity, resulting in a more established focus on supplement use to meet this body ideal among males compared to females [40].
Reasons for dietary supplement use
The most frequent reported reasons for use of DS among our university students, where “to maintain or improve health”, “improve mental or physical performance”, and to “increase muscle mass”, similar to what other student samples have reported [2, 5, 9,10,11]. In contrast to previous studies, we also looked at gender differences and found that significantly more males compared to females reported use of DS to improve performance and muscle mass, and to increase weight for appearance. This gender difference might underline the under-communicated body appearance pressure among male students [21], and their use of body modification methods.
Explanatory factors for use of muscle enhancing dietary supplements
Among males, being a fitness center member explained most of the variance in MEDS use, indicated by being four times more likely to use MEDS compared to not being a member. This result is in line with findings among Norwegian high school students [24] but contributes with new in-depth information with regards to adults [31, 32]. Also, in line with findings among high school students, although a higher physical activity level slightly increased the odds of using MEDS in males, our findings are of no coherence between use of MEDS and participation in organized sports [24]. Possible explanations might be the culture within fitness centers, where sale and use of such products are promoted [31], and where a focus on body appearance and shaping dominates, as in contrast to the performance, enjoyment, health, and social focus, more prominently promoted within organized sports [29, 30, 41].
In males, reporting to exercise “to increase muscle mass” almost doubled the odds of using MEDS, which supports previous findings among male American fitness center members [32]. This might be expected, as those who aim to enhance muscle strength might be more receptive to advertisement claiming to give you a quick fix to improve muscle strength. In contrast, reporting to exercise “to increase endurance” reduced the odds of using MEDS, which is logical based on less intensive statements related to the products’ effects on endurance, and the lower need of muscle building when aiming to improve endurance.
Finally, among males, we also found that being an exercise science student, as compared to other students, reduced the odds (OR: 0.47) of using MEDS. Our finding adds to current knowledge about differences in MEDS use between student groups. Firstly, because previous studies investigating differences between study programs have investigated differences in DS use in general, not specifically MEDS. Secondly, previous studies included nurse, medicine, and pharmaceutical students, as health-related students, who in contrast to exercise science students, do not have an educational background in sports nutrition and exercise physiology, and represent a very different health-related student group. The education of exercise science students provides them with sports nutrition and exercise knowledge which might have equipped them with lifestyle related media literacy. This argument only relies on the authors knowledge about exercise science students’ curriculum, as we did not measure knowledge about supplements in our sample. However, one study supports our suggested explanation, by finding that students with higher media literacy were less likely to be DS users [14]. Also, exercise science students are exposed to a social environment which does not emphasize the need for supplements and special product in addition to, or at the expense of, real foods.
In female students, internalization of the athletic body ideal and exercising to increase muscle mass, being two highly coinciding elements, partly explained the variance in use of MEDS, after adjusting for all other variables in the regression model. The finding that females who internalized the athletic body ideal and exercised to increase muscle mass, were almost two times more likely to use MEDS, is novel among adults. However, it supports previous findings among Norwegian adolescent girls [24], and further underline that being occupied with improving physical appearance towards the muscular body ideal, takes part in explaining the use of MEDS.
Based on our finding that explanatory factors vary between genders, one could speculate whether males’ habits related to use of MEDS are more affected by the environment they engage in (exercise context and study program), while females’ habits are more strongly driven by their own demands and perceived needs to meet ideals (internalization). Importantly, in the discussion of explanatory factors for use of MEDS in both males and females, it is necessary to point out that the regression models for both genders only partly explained use of MEDS, which leaves room for further investigation of other explanatory factors which were not measured in this study. As an example, we were not able to assess energy and nutrient intake in the current study, and we only assessed current use of supplements without asking about duration and amount of use per supplement. The inclusion of these aspects of use might be especially important in future studies aiming to investigate and reflect upon potential long-term health consequences of such use. Also, considering our study design, we were not able to explore causation. Therefore, we cannot be sure whether students who are introduced to e.g., an exercise science program or a fitness center, develop specific behaviors in terms of using or not using MEDS, or whether individuals with specific characteristics are more prone to engage in such environments, and at the same time use such supplements. Longitudinal studies to better investigate direction of associations are needed in future research.
Importantly, our sample is comparable to previous student samples regarding age, BMI, and gender distribution within the sample. However, our sample differ by representing both exercise science students in addition to non-health and non-exercise science students. Also, in contrast to most studies, our sample included several universities, representing students from all parts of Norway.
Strengths and limitations
Our study included a large sample size, compared both male and female students, and included scarcely investigated explanatory factors for use of MEDS. Despite the large sample size, a low response rate may impair generalization, and well-known biases are related to self-report of physical activity and exercise. Finally, based on our cross-sectional study design, cause-effect cannot be discussed.
Perspectives
Because higher education is assumed to lead to enhanced competence to practice source criticism and to make evidence-based lifestyle choices, the high frequency of DS and MEDS use among Norwegian university students, is surprising. Although we found less frequent DS and MEDS use compared to previous studies, the frequency of, reasons for, and explanatory factors for use, such as appearance, is of concern due to the potential negative physical and mental health effects. Variables related to body idealization are found to reduce well-being and mental health. Therefore, the use of MEDS can be related to a condition of less favorable mental health. Since studying exercise science seemed to result in lower frequency of MEDS use in our study, increased knowledge about health, exercise, and nutrition, might be important to prevent uncritical use of such supplements. Changes are also necessary within the fitness center industry, as this exercise context is known to promote idealization of specific body types in addition to promoting and selling MEDS.