Revista Adolescência e Saúde

Revista Oficial do Núcleo de Estudos da Saúde do Adolescente / UERJ

NESA Publicação oficial
ISSN: 2177-5281 (Online)

Vol. 13 nº 4 - Oct/Dec - 2016

Original Article Imprimir 

Páginas 49 a 56

Assessment of use frequency and knowledge of university students about vitamins and dietary supplements

Evaluación de la frecuencia de uso y del conocimiento de adolescentes universitarios sobre vitaminas y suplementos alimenticios

Avaliação da frequência de uso e do conhecimento de adolescentes universitários sobre vitaminas e suplementos alimentares

Autores: Eliane Mara Cesário Pereira Maluf1; Veruska Peron2; Anne Twardowsky Di Donato3; Paloma Matiazzo Peña Lupiañes4; Patrícia Rigon Vasconcellos de Souza5; Pedro Henrique Pedruzzi Segato6; Cristina Terumy Okamoto7

1. PhD in Internal Medicine, Paraná Federal University (UFPR). Pediatrics Specialist, Brazilian Pediatric Society. Works in the Epidemiology Sector, Paraná State Health Bureau, Curitiba, Paraná State, Brazil. Professor, Undergraduate Medicine Course, UP and UFPR. Clinical Practice Department, UFPR and Family Health (Mother and Child Area), Positivo University. Paraná Federal University (UFPR) and Positivo University (UP). Curitiba, Paraná State, Brazil
2. Graduand in Medicine, Positivo University (UP). Curitiba, Paraná State, Brazil
3. Graduand in Medicine, Positivo University (UP). Curitiba, Paraná State, Brazil
4. Graduand in Medicine, Positivo University (UP). Curitiba, Paraná State, Brazil
5. Graduand in Medicine, Positivo University (UP). Curitiba, Paraná State, Brazil
6. Graduand in Medicine, Positivo University (UP). Curitiba, Paraná State, Brazil
7. PhD in Health Sciences, Pontifical Catholic University in Paraná (PUC, Paraná State). Pediatrician with specialty in Neonatology, Osaka State University, Japan. Works with the Intensive Care Team, Pequeno Príncipe Children's Hospital, Hospital do Trabalhador. Professor, Undergraduate Medicine Course, years 3, 4 and internship, Positivo University. Pediatrics - Neonatology, Positivo University (UP). Curitiba, Paraná State, Brazil

Veruska Peron
Rua Martim Afonso, 1168, 1706, Mercês
Curitiba, PR, Brasil. CEP: 80430-100

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How to cite this article

Keywords: Vitamins, dietary supplements, adolescent health, self medication.
Palabra Clave: Vitaminas, suplementos dietéticos, adolescente, automedicación.
Descritores: Vitaminas, suplementos dietéticos, adolescente, automedicação.

OBJECTIVE: This research aims to know the use frequency of vitamins and supplements, identify the main motivations of its use and to evaluate the knowledge of university students around 18-19 years old about these substances.
METHODS: Was performed a cross-sectional study with 266 students of a private university of Curitiba-PR.
RESULTS: Of the total, 52.3% of the participants were female, and 27% of those said to use some of the substances listed, 8.6% being vitamins, 12% supplements and 6.4% both. The internet was the most cited research source of information for 73.3%, followed by health professionals (67.7%), newspapers/magazines/tv (42.9%), friends (25.2%) and gym instructors (16.2%). The average amount of correct answers for the 7 questions asked about vitamins was 3.5, and for those about dietary supplements was 3.4. About the motivations for the consumption of supplements and vitamins, the major reason was to increase muscle strength (59%), then to increase immunity (52%) and for beauty purposes (52%).
CONCLUSION: This study allowed a better understanding of today's teenager's profile, who are under the strong influence of internet and have a major concern about muscle strength, adopting some habits without proper scientific evidences.

OBJETIVO: Esa pesquisa tiene por objetivo conocer la frecuencia de uso de suplementos alimenticios y complejos vitamínicos, identificar las principales motivaciones para su uso y evaluar el conocimiento sobre tales sustancias entre universitarios de 18 a 19 años.
MÉTODOS: se realizó un estudio descriptivo transversal abordando 266 universitarios de una universidad privada de Curitiba-PR.
RESULTADOS: Del total, 52,3% de los participantes eran del género femenino y 27% de éstos contestaron hacer uso de alguna de las sustancias estudiadas, siendo 8,6% de vitaminas, 12% de suplementos y 6,4% de ambos. Internet fue lo más citado por los entrevistados como fuente para búsqueda de informaciones por 73,3%, seguido por los profesionales de salud (67,7%), diarios/revistas/tv 42,9% y con menor expresión, amigos 25,2% e instructores de gimnasio 16,2%. Los promedios de aciertos de las 7 preguntas sobre vitaminas fueron de 3,5, y para las de suplementos, de 3,4 preguntas. En lo que se refiere a las motivaciones para el consumo de polivitamínicos y suplementos alimenticios, el aumento de la fuerza muscular fue lo más citado (59%) seguido por el aumento de la inmunidad (52%) y por el deseo de belleza (52%).
CONCLUSIÓN: Este estudio permitió delinear el perfil actual del joven, que sufre gran influencia de internet, valorando el aumento de su fuerza muscular arriba de la búsqueda de evidencia científica sobre los beneficios de las sustancias que ingiere.

OBJETIVO: Essa pesquisa visa conhecer a frequência de uso de suplementos alimentares e complexos vitamínicos, identificar as principais motivações para seu uso e avaliar o conhecimento sobre tais substâncias entre universitários de 18 e 19 anos.
MÉTODOS: Realizou-se um estudo descritivo transversal abordando 266 universitários de uma universidade privada de Curitiba-PR.
RESULTADOS: Do total, 52,3% dos participantes eram do gênero feminino e 27% destes responderam fazer uso de alguma das substâncias estudadas, sendo 8,6% de vitaminas, 12% de suplementos e 6,4% de ambos. A internet foi a mais citada pelos entrevistados como fonte para busca de informações por 73,3%, seguida pelos profissionais de saúde (67,7%), jornais/revistas/tv 42,9% e com menor expressão, amigos 25,2% e instrutores de academia 16,2%. As médias de acertos das 7 questões sobre vitaminas foi de 3,5, e para as de suplementos, de 3,4 questões. No que se refere às motivações para o consumo de polivitamínicos e suplementos alimentares, o aumento da força muscular foi o mais citado (59%) seguido pelo aumento da imunidade (52%) e pelo desejo de beleza (52%).
CONCLUSÃO: Este estudo permitiu delinear o perfil atual do jovem, que sofre grande influência da internet, valorizando o aumento da sua força muscular acima da busca de evidência científica sobre os benefícios das substâncias que ingere.


The construction of personal identity that occurs during adolescence necessarily includes the body. According to Outeiral 1, the body plays an important role in peer acceptance or rejection at this time. Teenagers start to compare their bodies with idealized shapes and also those of their peers, and it is through this identification and comparison with other youngsters that they begin to build up specific ideas of their body images.

Today, many adolescents are clearly very dissatisfied with their own body images. In 2008, a study of 1,381 teens between 11 and 17 years old in the Saudades municipality, Santa Catarina State, found that the prevalence of body image dissatisfaction reached 60% (boys = 54.3%, girls = 65.2%; p < 0.05)3. One of the explanations for this phenomenon is the marked impact of media on this generation2.

Damasceno et al.3 affirm that body image dissatisfaction rises in parallel to media exposure of standards of beauty that are hard to attain. The current generation of adolescents seems more likely to try and resolve this dissatisfaction through esthetic abuses, compared to previous generations and even adults, as there are three factors involved: the lack of confidence inherent to adolescence; spread of different types of media during the past few decades (particularly television and the internet) that spotlight and underscore unreal body images; and new tools such as steroids, dietary supplements, vitamin complexes and plastic surgery promising ideal bodies, but also possibly constituting health hazards3.


The objective of this study is to explore the frequency with which dietary supplements and vitamin complexes are used, identifying the main reasons behind consumption of vitamins and dietary supplements, while evaluating knowledge about indications and proven risks and benefits related to the use of these substances among students between 18 and 19 years old enrolled at a private university in Curitiba, Paraná State. This knowledge will contribute through actions designed to enhance adolescent health.


The target population of this descriptive cross-sectional study consists of Positivo University students in Curitiba, Paraná State. Data were collected through a self-completed questionnaire that included social and economic information with fourteen questions assessing their knowledge: Questions 1 to 7 addressed vitamins, followed by Questions 8 to 14 explored dietary supplements, adapted from Santos and Barros.4 Moreover, this questionnaire included an item on personal motivations for consuming vitamins and supplements. The data were collected between June and November 2014, after project approval by the Positivo University Ethics and Research Committee on April 3, 2014, under Nº 579.812.

The respondents were selected through compliance with inclusion criteria: university students more than 18 years old and less than 20 years old signing Deeds of Informed Consent. Incomplete questionnaires were excluded. The sample was selected through a random draw of sealed, opaque envelopes from three courses in each of the major fields of knowledge: Health Sciences, Human Sciences and Exact Sciences, resulting in a total of nine courses drawn. The Health Sciences courses drawn were: Medicine, Physical Education and Nutrition; for the Human Sciences area: Law, Administration, Publicity and Advertising; and for Exact Sciences: Mechanical Engineering, Computer Engineering and Architecture. The questionnaires were completed in classrooms and elsewhere during breaks between classes. The number of respondents in each area was proportional to the number of students enrolled in these areas.

Statistical Analysis

The results of the assessments were tabulated and expressed through means and standard deviations or frequencies and percentages. For the frequency analysis, Microsoft Office Excel 2007 was used; with the GRAPHPAD PRISM 5.0 statistical package (San Diego California, USA) selected for the other analyses.


After screening, 266 students were included in this study, with a mean age of 18.6 ± 0.5 years old and an average of 19 years old, of whom 52.3% were female (139) and 47.7% (127) were male. In terms of ethnicity, most 84.2% (224) were white and 13.2% (35) were mixed race. Other ethnicities together totaled 2.6% (7). In terms of income, 12.5% (33) of the respondents reported family incomes of up to R$ 2,000.00; 39.5% (105) reported incomes between R$ 2,000.00 and R$ 6,780.00 and 48.1% (128) reported incomes of more than R$ 6,780.00.

Respondent attendance by course area was highest in the Human Sciences area at 44% (117) of the respondents, followed by the Exact Sciences area at 33.1% (88) and finally the Health Sciences area at 22.9% (61). In terms of semesters, 50% (133) of the respondents were in the first semester and 38.7% (103) in the second semester; the third and fourth semesters together accounted for 10.5% (28) of students participating in this study.

In terms of their consumption of vitamins and dietary supplements, 72 (27%) replied that they took at least one of these substances, compared to 194 (73%) who said that they did not. Among the 72 respondents reporting consumption, 23 (8.6%) took only vitamins, 32 (12%) only supplements and 17 (6.4% of the total number of respondents) stated that they took vitamins and supplements concomitantly. The full distribution is presented in Table 1. Among the vitamin users, 23 (57.5%) were female and 17 (42.5%) male. Among students taking dietary supplements, 16 (32.6%) were female and 33 (67.4%) male.

For adolescents taking vitamins distributed by course, it was found that 23.6% are enrolled in Administration, followed by Architecture with 23.3% and Law in third place with 22.2% of the students taking these substances (Table 2).

In terms of the distribution of adolescents taking supplements by course, it was noted that the highest percentage (30.2%) was found in the Administration course, followed by Architecture with 17.2% and Law with 13.3% (Table 3).

The source of information most commonly used by the respondents was the internet for 73.3% (195) of them, followed by healthcare practitioners for 67.7% (180). Newspapers, magazines and television ranked third, mentioned by 42.9% (114) of the respondents, followed by friends for 25.2% (67) and gym instructors for 16.2% (43).

The vitamins most commonly consumed by this sample were multivitamins for 57.5% (23) followed by vitamin C (15%) and vitamin D (7.5%). For supplements, whey protein was the most frequently mentioned, accounting for 85.7% of the supplements (42), followed by creatine at 22.4% (11) and branch chain amino acids (BCAA) for 20.4% (10). Respondents taking vitamins (n=40) have been taking them for a mean duration of 18.9 ± 24.2 months with a median of 12 months. Respondents taking supplements (n=49), had been taking them for a mean of 15 ± 16.3 months and a median of 12 months.

When questioned about taking vitamins with or without medical prescriptions, 21 (52.5%) said that they were taking them with no medical indication, compared to 19 (47.5%) recommended by physicians. Similarly, most of the students taking supplements were doing so without medical recommendations: 35 (71.4%). Only 14 students, 28.6% of the supplements users were doing so under the supervision of a physician.

The assessment of the knowledge of these adolescents about the substances they are taking showed, out of a total of 14 questions, correct answers in a mean of seven questions, ± 2.4 among all the respondents. The mean number of correct answers for only the seven questions involving vitamins reached 3.5 ±1.5 questions; remaining the same for questions on supplements: 3.4 questions, ±1.5.

Among the questions, those with the fewest number of correct answers addressed the role of vitamin C for preventing colds and flu, and the role of chitosan for building up muscle mass, with 6.0% and 8.3% correct answers, respectively. The question with the largest number of right answers explored the idea of vitamins as natural substances that are essential to health, with 86.8% correct answers. Only 67.3% of the respondents felt that supervision by a physician and / or a nutritionist was vital for taking dietary supplements.

When analyzing the distribution of correct answers in the seven questions about vitamins, in terms of consumption, it was noted that youngsters not taking vitamins scored the same number of correct answers on average than those taking them without being recommended to do so by a physician: 3.5 compared to 3.2 respectively. In turn, those taking vitamins under medical supervision posted a higher average for correct answers: 4.1 questions. The variables were analyzed for significant differences through variance analysis (ANOVA). The complete results are shown in Table 4.

With regard to the distribution of correct answers for dietary supplements, it was noted that students taking supplements answered one question more correctly on average than non-users. The Tukey test (ZAR, 2009) showed a significant difference (p<0.001) between the mean correct answers of these two groups. The results for students taking supplements with and without medical supervision are very close: 4.5 versus 4.2, respectively, there was not statistically significant difference between the groups taking them with and without medical supervision. The complete results are shown in Table 5.

With regard to the reasons for taking multivitamins and dietary supplements, building up muscle strength was mentioned most frequently (59%) followed by greater immunity (52%) and wanting to look good (52%), followed by preventing and curing flu (33%), lowering stress (30%), looking younger (14%) and boosting libido (5%). Looking only at vitamin consumers, the main reason was still building up muscle strength (68%), followed by greater immunity (65%), wanting to look good (63%), preventing and curing flu (38%), lowering stress (20%), looking younger (20%) and boosting libido (5%). Looking only at supplement users, the main reason - similar to the other groups - remains building up muscle strength (79%), followed by wanting to look good (58%), greater immunity (54%), preventing and curing flu (31%), lowering stress (19%), looking younger (10%) and boosting libido (8%).


The frequency of teenage university students taking vitamins and / or supplements noted in this study reached 27%. In a study conducted in 2002 with university students between 17 and 24 years old at a private university in São Paulo, Santos and Barros found a 30% rate for vitamin users. The reason for this difference was not investigated, but it might be due to the different methodology used in the survey or different behavior among young people in these regions.

Noting a higher prevalence of supplement users among males is reflected in the literature, as in the studies by Hallack et al. (2007).5 and Albino et al. (2009)6, where males are the main consumers of supplements, at levels varying from 79% to 86%. These findings may be explained by the fact that young men are eager to increase their muscle strength.

In this study, the prevalence of vitamin use was higher among students in the Human Sciences at 15.3%, followed by Exact Sciences area at 13.5% and then the Health Sciences area at 6.3%. The survey by Santos and Barros also showed a higher proportion (27.8%) of vitamin consumers in the Human Sciences area than in the Biological Sciences area (21.9%) and Exact Sciences area (19.5%)4.

The internet was the most frequently mentioned (73.3%) source of information on vitamins and dietary supplements, outstripping guidance from a healthcare practitioner (67.7%). It is a matter of concern that so many adolescents based their opinions on somewhat unreliable sources. It is also worthwhile stressing that several studies - such as those by Glynn et al. 7 and Fortmann et al.8 - show that there is little scientifically proven information on dietary supplement consumption available to the public in general. Consequently, it is probable that the population consuming these products is not endowed with sufficiently solid knowledge on this matter.

When analyzing the vitamins most widely consumed by university students in São Paulo4, vitamin C was mentioned most frequently (20.3%), followed by multivitamins (15.9%). In this survey, multivitamins ranked first at 57.5% and vitamin C second at 15% of their users. Similar figures were found in a survey conducted in 2006 in the USA of 8,860 respondents, with multivitamins the most commonly taken at 50% preference 10,11.

In this survey, whey-based supplements were the most widely consumed (85.7%), followed by creatine (22.4%). This distribution was similar to the study by Pereira12 conducted at Campinas University, which showed that 42.7% of the supplements taken were protein-based. According to the survey conducted by Brunacio et al.13, protein supplements are also the most widely used by people living in the city of São Paulo.

This survey did not assess the quantities taken, due to different individual needs. However, it was noted that most vitamin and supplement users (52.5% and 71.4% respectively) took these substances with no medical supervision. These adolescent university students did not seek guidance from a healthcare practitioner, engaging in self-medication and consequently at risk of ingesting doses far higher than the nutritional recommendations, which could lead to intoxication14,15. Similar results were found by Santos and Barros, with only 21% of consumers stating that they took vitamin products under the supervision of a physician, nutritionist or a trainer.

In terms of analyzing right and wrong answers to the questions presented to the participants, it was noted that the students had a good understanding of the concept of vitamins as natural substances that are essential to health, with 86.8% correct answers. In counterpart, the lower level of correct answers to the question on vitamin C shows that university students in general still believe that vitamin C can cure and prevent flu. This belief dates back to the start of the last century, when vitamin C sales by the pharmaceutical industry began, buoyed by this justification, but which had already been demystified4.

The percentage of wrong answers to the question on the need for a doctor´s prescription in order to take these substances reached 32.7%, indicating that one third of the respondents were unaware of the importance and need for guidance from a healthcare practitioner when taking vitamins and / or dietary supplements. Only 67.3% of the respondents acknowledged this importance, with only 30.6% taking supplements under medical supervision and only 47.5% of vitamin users. This shows that, despite the need for specialized oversight supervision of the use these substances, only a minority seeks this advice. This is due partly to easy access and strong commercial appeals that encourage the consumption of these substances17.

With regard to the reasons for taking multivitamins and dietary supplements, building up muscle strength was mentioned most frequently (59%), followed by greater immunity (52%) and wanting to look good (52%). Similarly, a study at Campinas University presented building up muscle mass as the main reason for taking protein supplements18. The study by Santos and Barros showed that the main reason for university students taking vitamins/supplements was to "ensure health" (24.9%), followed by "offsetting shortfalls in diet" (22.1%) and "preventing diseases" (16.2%).


The results presented above indicate that adolescents constitute a population at risk for abusing these substances, as many of the university students taking vitamins and / or supplements do so without recommendation or oversight by a healthcare practitioner, while most of them (73.3%) use the internet as their main source of information.

Consequently, nutritional health or dietary education lectures on university campuses may help lessen the vulnerabilities identified through the research data, as scientific information would be disseminated in order to eliminate mistaken beliefs and risk factors for this population.

It is expected that the knowledge provided by this project will underpin the preparation of lectures and campaigns on this topic at other universities, and even secondary schools, providing an initial incentive for heightening awareness of this issue among university students.


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