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R E S E A R C H A R T I C L E Open Access
Prevalence and patterns of dietary
supplement use in elite Spanish athletes
Gabriel Baltazar-Martins
1
, Diego Brito de Souza
1
, Millán Aguilar-Navarro
1,2
, Jesús Muñoz-Guerra
3
,
María del Mar Plata
4
and Juan Del Coso
1*
Abstract
Background: Dietary supplementation is a common strategy to achieve a specific health status or performance
benefit. Several investigations have focused on the prevalence of dietary supplement use by athletes. However,
information on how athletes manage the use and purchase of dietary supplements is scarce.
Methods: Five hundred and twenty-seven high-performance athletes (346 males and 181 females), participating in
individual and team sports, completed a validated questionnaire about use and purchase patterns of dietary
supplements. The dietary supplements were categorized according to the International Olympic Committee (IOC)
consensus.
Results: Sixty four percent of the athletes (n= 337) used dietary supplements (median = 3; range 1 to 12). Age,
sex, type of sport, level of competition, and professionalism influenced the prevalence of dietary supplement use
(all p< 0.05). The most prevalent dietary supplement consumed was proteins (41%; n= 137), followed by amino
acids/BCAA-based supplements (37%; n= 124). Additionally, as per group of supplements according to IOC consensus,
18% of the supplements were rated as having a low level of scientific evidence (e.g., glutamine, HMB, L-carnitine, etc).
Most athletes (45%, n= 152) purchased dietary supplements in a store and 24% (n= 81) obtained them from a sponsor.
Most athletes also (42%, n= 141) reported a self-organization of supplementation and did not consult with any
professional. Last, 81% (n= 273) of athletes consuming supplements did not know any platform to check supplement
safety/quality. For those who do not use dietary supplements (36% of the total sample, n= 190), most reported that they
do not consider supplements necessary (72%, n= 137).
Conclusion: Dietary supplementation appears to be widely used in sport with a considerable proportion of
athletes consuming supplements with low level of scientific evidence. Additionally, athletes seem to rely on
inadequate sources of information and may be largely unaware of sources to detect supplement
contamination.
Keywords: Dietary supplement, Ergogenic aid, Athletic performance, Elite athlete
Background
The quest for optimal nutrition has been gaining im-
portance among athletes as the level of sport competi-
tion has become more demanding [1]. At the elite level,
the constant quest for excellence is obtained through
regular and planned training, while the advances in nu-
trition and supplementation can aid to improve athlete’s
performance, recovery, health and well-being [2].
A dietary supplement is a commercially available prod-
uct that is ingested in addition to the habitual diet. Ath-
letes often use dietary supplements as a strategy to
achieve a specific health outcome or exercise perform-
ance benefit [3,4]. Although some consider that the use
of nutritional supplements is unnecessary when athletes
have a well-balanced diet [5], dietary supplement use has
grown significantly in the past years [6]. Dietary supple-
ments are available for the general population, but the
use of these supplements is higher in elite athletes than
in non-athletes or recreationally active individuals [3].
The overemphasis of dietary supplement use, as
© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
* Correspondence: jdelcoso@ucjc.edu
1
Exercise Physiology Laboratory, Camilo José Cela University, C/ Castillo de
Alarcón, 49. Villafranca del Castillo, 28692 Madrid, Spain
Full list of author information is available at the end of the article
Baltazar-Martins et al. Journal of the International Society of Sports Nutrition
(2019) 16:30
https://doi.org/10.1186/s12970-019-0296-5
endorsed by internet and social media, along with the ef-
forts of nutritional supplement companies to sponsor re-
markable athletes [7] have aided at increasing the use of
these products worldwide. In 2017, global sales of sup-
plements reached US $128 billion [8]. Although the use
of supplements varies across different sports, its usage is
generally higher in men than in women and increases
with age [4]. In addition, the athletes involved in short
sprint-based activities typically consume less dietary sup-
plements than athletes competing in endurance-based
activities [9].
The prevalence of dietary supplement use by athletes
has been the topic of several investigations [10,11]and
their results have been recently reviewed and systemat-
ically analyzed [4]. Overall, the prevalence of supple-
ment consumption ranges from approximately 48 to
81% [12–17] while proteins and multivitamins are the
most popular supplements. The reasons reported by ath-
letes for using dietary supplements are diverse although
are mainly related to health-related issues [16], physical
and mental performance improvement [18], and increased
rate of recovery [1]. However, the patterns of use and pur-
chase of supplements have not been well investigated.
Athletes often rely on their coaches [15], family [16],
and friends/teammates [19] as their preferable sources
of reliable information for their use of dietary supple-
ments. However, sports nutritionists or scientists are
rarely the main source of information to plan a supple-
mentation program [20], even at the elite level. This may
lead athletes to an excessive and/or incorrect use of diet-
ary supplements along with possible adverse interactions
due to polypharmacy [21]. In addition, there are signifi-
cant risks associated with the use of dietary supple-
ments, such as the absence of active ingredients, the
presence of harmful substances, or even the presence of
doping agents [22]. With rates of contamination between
12 and 58% [23], the likelihood of unintended doping
with the use of supplements is high. Lastly, athletes are
not always aware of the risks associated with purchasing
supplements and rarely inform themselves to confirm
the quality and safety of the selected supplement [20].
The internet has become a preferable site to purchase
supplements and thus, the easy access to contaminated
nutritional supplements and “black market”products
might constitute a risk for public health.
Since athletes often use dietary supplements with no
clear understanding of their effects and risks [24], it be-
comes critical to provide information about the patterns
of use and purchase of dietary supplements in samples
of elite athletes. This information might help to provide
nutritional education approaches that reduce the risk
associated with dietary and nutritional supplementation
through better informed the athletes. Taking into ac-
count the lack of research in Spanish athletes [25,26],
the present study aimed to determine the prevalence of
supplement use by elite athletes while describing how
athletes manage dietary supplements use.
Methods
Participants
Five hundred and twenty-seven athletes (346 males and
181 females) volunteered to participate in this investiga-
tion by filling out a validated and standardized question-
naire about the use of dietary supplements [27]. The
athletes were considered elite because all of them were
training and competing in high-performance programs
of different national sports federations. Specific informa-
tion about the study sample can be obtained in Table 1.
The questionnaire was provided by email to athletes
with the help of staff from different national federations
and announcements in sport performance centers. Thus,
it was unfeasible to record the number of athletes soli-
cited for this investigation. Forty-five athletes were ex-
cluded from the study because they did not complete
the questionnaire and 4 questionnaires were not consid-
ered valid because they contained duplicate information
in all questions. Informed consent was obtained with the
questionnaire. The study was approved by the Camilo
José Cela University Ethics Committee and it was carried
out in accordance with the procedures approved by the
Declaration of Helsinki.
Questionnaire
The questionnaire used in this investigation has been
previously validated to assess the prevalence of dietary
supplement use and to obtain information about the in-
dividual consumption patterns in the last year [27]. The
questionnaire also assessed information on socio-
demographic variables, sport level, and professionalism.
This questionnaire was developed by a group of experi-
enced sport scientists, its construct validity was verified
by a group of six experts in nutrition, sports sciences
and chemistry (Aiken’s V = 0.97 for pertinence and 0.82
for relevance of the questions) and its reliability has been
measured by a test-retest performed 4 weeks apart. The
questionnaire contained a definition of a dietary supple-
ment according to the latest consensus statement of the
International Olympic Committee (IOC; [3]). Through
81 questions, it also asked participants about the use of
performance enhancing substances, supplements for
weight control, supplements to increase the rate of
recovery, medicaments, and other substances. The ques-
tionnaire allowed athletes to report the total number,
type of supplement used, and season of consumption
(pre-season, competitive periods, or all year). The ques-
tionnaire also had a section to be filled out only by those
who did not report any supplement use in order to as-
certain the reasons for their lack of use.
Baltazar-Martins et al. Journal of the International Society of Sports Nutrition (2019) 16:30 Page 2 of 9
The questionnaire was organized to obtain informa-
tion about a) sociodemographic information, sport
discipline, and level of competition; b) prevalence and
frequency of dietary supplement usage; c) reasons for
the use of supplements, sources of information about
supplementation, and contamination and purchase
conditions. Participants filled out the questionnaire
between July 2017 and May 2018. In order to help
athletes to identify supplements, examples for each
category were provided.
Analysis of dietary supplements by group
To improve the applicability of the results, each supple-
ment was individually notated and grouped according to
the groups of the IOC consensus statement [3], as
follows:
1. “Performance enhancement”, which included
caffeine, beta alanine, creatine, sodium bicarbonate,
carbohydrate foods, and carbohydrate powders.
2. “Immune health”, which included antioxidant
supplements, probiotics, and vitamin C.
3. “Micronutrients”, which included iron supplements,
magnesium, folic acid, calcium, zinc, selenium,
multivitamin supplements, and electrolytes.
4. “Improve recovery & injury management”, which
includes joint support supplements (glucosamine,
chondroitin, collagen), recovery supplements (mixes
of carbohydrate and protein powders labelled as a
“recovery product”), omega- 3 &- 6 polyunsaturated
fatty acids, and curcumin.
5. “Body composition changes”, which includes
protein powders (whey protein mixes, casein,
calcium caseinate, plant/meat/egg-based protein
powders).
6. “Low level of evidence supplements”, which
includes: glutamine, single amino acids/branched-
chain amino acids (BCAA), beta-hydroxy beta-
methylbutyrate (HMB), L-carnitine, spirulina, royal
jelly, citrulline, probiotics, taurine, conjugated
linoleic acid, co-enzyme Q10, and fat burners,
among others.
It is important to clarify that some dietary supplements
may be included in different categories, as reported in the
IOC consensus [3]. However, we have selected the most
pertinent category based on scientific evidence. This is the
case of “carbohydrate powders”(including maltodextrin,
amylopectin, and powdered isotonic blends) and “carbo-
hydrate foods”(energy bars, energy gels, and other miscel-
laneous carbohydrate-rich products) which have been
included in the “performance enhancement”category.
Although the IOC consensus also considers them as sup-
plements for immune health, the evidence so far mainly
supports their role in the maintenance of exercise inten-
sity in endurance sports [28]. Similarly, other dietary sup-
plements reported to have a low level of evidence have
been included in a category of their own (“low level of
evidence supplements”). Although some of these supple-
ments may be in a specific category in the IOC consensus
statement, these are reported in said document has having
a low level of evidence (e.g. glutamine and HMB). Finally,
Table 1 Socio-demographic characteristics of the participants
and distribution of athletes who reported use/not use of
supplements in the last year
Total Frequency % (n)
Yes No Pvalue
Gender
Male* 346 67% (232) 33% (114) 0.04
Female* 181 58% (105) 42% (76)
Total 527 64% (337) 36% (190)
Age Range
<15–20 years* 111 30% (33) 70% (78) < 0.01
21–25 years 123 65% (80) 35% (43)
26–30 years* 106 77% (82) 23% (24)
31–35 years 58 74% (43) 26% (15)
36–40 years* 62 79% (49) 21% (13)
> 41 years 66 74% (49) 26% (17)
Sport
Body Building* 38 95% (36) 5% (2) < 0.01
Cycling 36 86% (31) 14% (5)
Athletics 238 77% (184) 23% (54)
Triathlon 75 77% (58) 23% (17)
Aquatics 31 77% (24) 23% (7)
Weightlifting 16 75% (12) 25% (4)
Football 8 75% (6) 25% (2)
Volleyball 8 75% (6) 25% (2)
Others 112 74% (83) 26% (29)
Canoe/Kayaking 11 73% (8) 27% (3)
Field Hockey 11 64% (7) 36% (4)
American Football* 68 57% (39) 43% (29)
Golf* 29 55% (16) 45% (13)
Gymnastics* 17 53% (9) 47% (8)
Basque pelota (jai alai)* 15 53% (8) 47% (7)
Level of competition
National* 262 71% (262) 29% (77) < 0.01
International* 265 57% (265) 43% (113)
Professional
Yes* 85 75% (64) 25% (21) 0.02
No* 438 61% (269) 39% (169)
(*)The distribution was different from the value expected at p< 0.05
Baltazar-Martins et al. Journal of the International Society of Sports Nutrition (2019) 16:30 Page 3 of 9
athletes from 23 different sport disciplines filled out the
questionnaire, but sport disciplines with less than 8 partic-
ipants were grouped in the “others”category.
Statistical analysis
After the data collection, data was organized, checked and
analysed with the statistical package SPSS 20 (SPSS Inc.,
Chicago, IL). Participants and quantitative data of dietary
supplements are expressed by frequencies and percentages.
Because the number of supplements used followed a non-
normal distribution, median and range have been calculated
for this variable. The 16 most-used supplements have been
presented for clarity. The differences in the distribution of
dietary supplements use across the groups made by socio-
demographic variables (Table 1) were tested with crosstabs
and the Chi Square test, including adjusted standardized re-
siduals. The significance level was set at p< 0.05.
Results
From the total sample, 64% of the athletes (n= 337) re-
ported habitual use of at least one dietary supplement in
the last year during any point of the season. The remaining
36%ofthesample(n= 190) did not report any supplement
use in the last year. Overall, male athletes reported a higher
use of dietary supplements than women (p= 0.04; Table 1)
while age was another variable that significantly modified
theprevalenceofuse(p< 0.01). Although all sports showed
a supplement usage frequency of at least 50%, body build-
ing was the discipline with the highest self-reported use of
supplements (Table 1). Cycling, athletics, triathlon, and
aquatics were also sport disciplines with high proportions
of athletes using supplements (Table 1). American football,
golf, gymnastics, and Basque pelota had lower than ex-
pected frequencies in the proportion of athletes that used
supplements (p<0.01; Table 1). The use of supplements
was higher in athletes that had national-level stand-
ings than athletes with international-level standings
(p< 0.01) while professionalism increased the use of
supplements (p= 0.02).
In total, 1056 supplements were reported; most of the
supplements were categorized as low level of evidence
substances, followed by micronutrients and performance
enhancement supplements (Fig. 1). In the sample of sup-
plements users, a median consumption of 3 supplements
per athlete was found with a range from 1 to 12 supple-
ments (Fig. 2). Still, 6% of athletes reported a use of ≥8
supplements in the last year. From the subsample of
supplement users, 47% reported consumption during the
whole season, 43% reported consumption only during
competitive periods, and 10% reported consumption
only during the pre-season. Proteins, amino acids/
BCAA, and multivitamins were the most consumed sup-
plements in the sample of supplement-users (Fig. 3). A
total of 36 different supplements were identified in the
questionnaire. Most of the athletes that consumed sup-
plements reported relying on him/herself for the obtain-
ing of valid and accurate information about the efficacy
of the supplements and they did not consult any profes-
sional for this matter (Fig. 4). The remaining athletes
reported seeking advice through physicians, nutritionists,
and coaches as alternative sources of information. The
most common site of purchase were physical supple-
ment stores while a high proportion of athletes directly
obtained supplements from sponsors or internet web-
sites (Fig. 5). Although 85% of the sample indicates that
they only used certified supplements free of doping
agents, 81% were not aware of any platform to verify
supplement safety/quality. This is because 92% of the
sample considered that supplements are safe and con-
trolled by the supplement company/brand. Only 40% of
athletes had knowledge of a Spanish national-based ap-
plication that certified permitted supplements and iden-
tified doping agents (i.e., NoDop App).
Among the athletes that did not report any use of sup-
plements (n= 190), the main reason was that they did
not consider them necessary to maintain their level of
fitness (Fig. 6). A low proportion of athletes did not con-
sume supplements because their family/coach did not
allow this practice.
Discussion
The aim of this study was to investigate the prevalence
of dietary supplement usage in elite athletes from differ-
ent sports and to provide information about how ath-
letes manage the use of these supplements. We gathered
information about the number and type of supplements
consumed in the last year, when and why the supple-
ments were consumed, along with data about purchasing
routines and certification of supplement quality/safety.
The current investigation was shaped by the recent sug-
gestions for improving research on dietary supplement
use as raised by Knapik et al. [4]. The investigation relied
on a questionnaire that included definitions and exam-
ples of dietary supplements. It also contained specific
categories of dietary supplements along with open and
closed questions for participants to respond to. A wide
variety of sports were solicited for questioning. Although
a similar aim has been pursued in several previous inves-
tigations [12–16], this current study is novel because it
expands upon the most common practices employed for
the management and administration of dietary supple-
ments in a sample of elite athletes. Finally, the study is
innovative because categorizes dietary supplements ac-
cording to the last consensus of the IOC [3].
Overall, the use of at least one dietary supplement was
reported by 64% of the study sample, a proportion within
the range of previous investigations carried out in similar
samples in Europe [1,14]. However, several demographic
Baltazar-Martins et al. Journal of the International Society of Sports Nutrition (2019) 16:30 Page 4 of 9
variables affected the proportion of athletes that con-
sumed dietary supplements in the last year. Sex, age, level
of competition, and professionalism influenced this pro-
portion. The sociotype of a typical dietary supplement
user is a 36–40-year-old male that competes at a national
level, but in a sport that allows professionalism. Interest-
ingly, age was the strongest predictor of dietary supple-
ment use which confirms this variable as an important
modulator of the decision to use supplements to obtain
performance and/or health benefits, as previously found
[13,29]. The use of dietary supplements by youngest ath-
letes is likely monitored by parents and coaches compared
with older athletes who might have more opportunity to
engage in unsupervised supplements use [30].
The sport discipline was another variable with great
influence in the proportion of dietary supplements use
(Table 1). The sport with the highest proportion of diet-
ary supplement use was bodybuilding, with 95% of
body-builders reporting the use of at least one supple-
ment/year. Cycling, athletics triathlon, and aquatics also
had high frequencies of dietary supplement use, as
observed in elite Portuguese athletes, where the number
of training hours –normally higher in endurance-based
activities-- was associated with an increased supplement
consumption [1]. Additionally, other studies also confirms
that endurance athletes appear to consume more supple-
ments than athletes engaged in sprint-based activities [9].
Interestingly, team sports (i.e., football, volleyball, field
hockey, etc) presented a non-significant lower proportion of
athletes that used supplements. This data coincides with
previous publications in samples of Spanish tennis [25]and
basketball players [12] where individual athletes reported a
higher use of supplements than in team sports (81% vs
58%). Even in the sports with the lowest proportion of sup-
plement use (i.e., gymnastics and Basque pelota), one out of
two athletes reported the supplement use. This data rein-
forces the idea that characteristics of the sport influence the
general use of dietary supplements in sports while it sup-
ports the establishment of dietary supplementation as a
common tool for athletes of all types of sport disciplines.
The number of consumed supplements also presented a
high interindividual variability with athletes consuming
between 1 to 12 dietary supplements, as previously found
[1,16] Although the median of supplement consumption
Fig. 2 Frequency of elite athletes according to the number of supplements used in the last year
Fig. 1 Distribution of dietary supplement use in elite athletes according to the categories used in the International Olympic Committee consensus
statement on dietary supplements and the high-performance athlete
Baltazar-Martins et al. Journal of the International Society of Sports Nutrition (2019) 16:30 Page 5 of 9
per athlete was 3 supplements per year, a high proportion
of athletes consumed more than 8 different supplements
and at different times of the season. This results suggest
that some athletes might be subject to the adverse interac-
tions of polypharmacy [21] while also laying out the idea
of excessive dietary supplement use amongst some ath-
letes. This is more evident by the high reliance of athletes
on themselves as being the main source to obtain accurate
information about the effect and efficacy of the supple-
ment while they referred themselves as a the main respon-
sible for the plan of supplementation (Fig. 4). As it has
been found, receiving dietary counseling by a qualified
professional - instead of relying on self-prescription - re-
sults in better-informed choices with respect to the use of
nutritional supplements related to performance, recovery,
and health [31]. This information points towards the
necessity of increasing the knowledge of the benefits and
risks of supplementation in the elite athlete population.
This result highlights the importance of elite athletes pla-
cing more reliance on sport nutritionists and scientists to
design their supplementation plans. A more informed ath-
lete population will likely reduce the strong effect of pur-
chasing multiple types of supplements that have been
driven by dietary supplement manufacturers.
The most consumed dietary supplements were pro-
teins, amino acids/BCAA, multivitamins, glutamine, and
creatine (Fig. 3). A very similar pattern for the type of
supplements consumed has been reported in other stud-
ies where proteins [32], multivitamins [31], and creatine
[29] were found to be the most consumed substances.
However, as a novelty of this investigation, the data indi-
cate that the most prevalent group of substances were
Fig. 4 Main source of information to determine the type, use, and utility of dietary supplementation in elite athletes
Fig. 3 Frequency of elite athletes using the 16 most taken supplements in the last year
Baltazar-Martins et al. Journal of the International Society of Sports Nutrition (2019) 16:30 Page 6 of 9
ones that had little scientific evidence (Fig. 1). This effect
was produced by the high number of supplements avail-
able in the market that contain minimal evidence of its
effectiveness. Although this in the first investigation that
suggests this finding, it could be ventured from previous
literature due to the gaps in knowledge about effective
nutrition and supplementation found in coaches and
athletes [24]. This outcome is likely the result of current
supplementation practices that imply a poor knowledge
about the effect and efficacy of supplements along with
reliance on sources with low credibility, at least in this
sample of high-performance athletes.
The internet is not only a readily accessible outlet for
quick purchases, but also a source of information for the
claimed effects of dietary supplements. It is also often
reported as a preference site of purchase [33], as it was
found in the present study. Nevertheless, the purchase
of supplements in physical stores was listed as the main
preference for athletes in this study. This might be justi-
fied by a possibly increased safety perception by athletes
when buying supplements directly to the vendor when
compared to buying online, but research on this topic is
scarce and the justification of purchase preference
merits further research. Because of their graphical at-
tractiveness and ability to interact/share, athletes often
prefer internet and social media as preferred tools for
obtaining information and/or educating themselves on
nutrition-related topics [29]. Possibly, an excessive
amount of information readily available on the internet
and a high engagement with social media [34] with mar-
keting campaigns aimed for sports practitioners, might
increase the risk for athletes not relying on other profes-
sionals to obtain advice.
Lack of legislation on dietary supplements worldwide,
the risk of contamination, and the absence of proper infor-
mation regarding their use and scientific basis [23,24]
may increase the risk for inadequate and excessive use of
dietary supplements or even inadvertent doping.
In the sample of athletes that took at least one supple-
ment, four out of five athletes did not know platforms to
check safety/quality of supplements. Most solely relied
on the brand name for quality and safety. Despite ample
evidence that confirms contamination in commercially
available products, athletes still purchased supplements
Fig. 6 Relative frequency of athletes not taking supplements according to the reasons for not using them
Fig. 5 Main site of dietary supplements purchases in elite athletes
Baltazar-Martins et al. Journal of the International Society of Sports Nutrition (2019) 16:30 Page 7 of 9
with the assumption of safety [23]. Furthermore, only a
relatively small percentage of the athletes not taking diet-
ary supplements reported fearing contamination of the
supplement. Together, all these results may indicate that
athletes are disturbingly unaware of the contamination
risks inherent in dietary supplements. Athlete supplement
education is a critical need. This is important to not only
reduce the cases of unintended doping [22], but to also
avoid unintentional intakes of substances that could po-
tentially have acute and long term side-effects [20].
This investigation presents some limitations that
should be discussed to improve the results’applicability.
Although we used a validated and reliable questionnaire
[27], the timeframe used to report the use of supple-
ments (i.e., “in the last year”) might have induced some
error due to imprecision in the number and type of sup-
plements reported. This might be important for those
subjects reporting a high number of supplements. We
used open and closed questions and provided examples
of each supplement category in an attempt to reduce re-
call inaccuracies. Additionally, although it was made
clear that the questionnaire was anonymous, it is pos-
sible that due to personal bias, some athletes may have
intentionally avoided reporting some information re-
garding supplement consumption. Finally, some athletes
showed some difficulty describing the type of supple-
ment they were taking. To avoid wrongfully identifying
supplements, an open space was provided in the ques-
tionnaire to fully describe the supplement (name, brand,
type, and any other extra information that they could re-
call) to improve the identification of each supplement.
Despite these limitations, the authors believe that the
article presents valuable information for the scientific
community about patterns of dietary supplementation
consumption.
Conclusion
In conclusion, the results of this questionnaire demonstrate
a widespread use of dietary supplements in elite athletes.
Socio-demographic factors that include age, sex, type of
sport, level of competition, and professionalism might influ-
ence the prevalence of dietary supplement consumption.
Although proteins and amino acids were the most con-
sumed supplements, substances with a low scientific basis
for their consumption were the most predominant group
of supplements. This is mainly due to the high number of
commercially-available dietary supplements that fulfill this
definition. Furthermore, athletes seem to rely on inadequate
sources of information when acquiring and using supple-
ments, with a considerable proportion of athletes engaging
in self-prescription and purchase without consulting an
accredited professional. Additionally, a high proportion of
athletes are unaware of the contamination risks that dietary
supplements may pose, which expose them to possible
inadvertent doping. Urgent nutritional education and con-
sulting should be made available to athletes and coaches,
emphasizing the role of the nutritionist, sport scientists,
and the acute and long-term side effects of incorrect plans
of supplementation.
Abbreviations
BCAA: Branched-chain amino acids; HBM: Beta-hydroxy beta-methylbutyrate;
IOC: International Olympic Committee
Acknowledgments
The authors would like to thank all the athletes who participated in the
study, as well as all the national federations that have collaborated in the
data collection process.
Authors’contributions
The study was designed by MAN, JMG, MMP and JDC; data were collected
by MAN, JMG, MMP and JDC; data were analyzed by GBM, MAN, DBS and
JDC; data interpretation and manuscript preparation were undertaken by
GBM, MAN, DBS and JDC. JMG and MMP critically reviewed the manuscript.
All authors approved the final version of the paper.
Funding
This study did not receive any fundings. During this study, Gabriel Baltazar-
Martins received a grant from the Spanish Agency for Health Protection in
Sport. Diego Brito de Souza received a scholarship from the Camilo José Cela
University to support his PhD studies.
Availability of data and materials
Please contact author for data requests.
Ethics approval and consent to participate
Informed consent was obtained from all participants with the questionnaire.
The study was approved by the Camilo José Cela University Ethics
Committee and it was carried out in accordance with the procedures
approved by the Declaration of Helsinki.
Consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing interests.
Author details
1
Exercise Physiology Laboratory, Camilo José Cela University, C/ Castillo de
Alarcón, 49. Villafranca del Castillo, 28692 Madrid, Spain.
2
Exercise and Sport
Sciences. Faculty of Health Sciences, Francisco de Vitoria University, Madrid,
Spain.
3
Department for Doping Control, Spanish Agency for Health
Protection in Sport, Madrid, Spain.
4
Department of Education, Spanish
Agency for Health Protection in Sport, Madrid, Spain.
Received: 11 April 2019 Accepted: 8 July 2019
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