SUPPLEMENT USE BY YOUNG ATHLETES
Department of Family and Nutritional Sciences, University of Prince Edward
13 March 2007
Journal of Sports Science and Medicine (2007) 6, 337 - 342
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|This paper reviews studies of supplement use among child and adolescent
athletes, focusing on prevalence and type of supplement use, as well
as gender comparisons. Supplement use among adult athletes has been
well documented however there are a limited number of studies investigating
supplement use by child and adolescent athletes. A trend in the current
literature revealed that the most frequently used supplements are
in the form of vitamin and minerals. While health and illness prevention
are the main reasons for taking supplements, enhanced athletic performance
was also reported as a strong motivating factor. Generally, females
are found to use supplements more frequently and are associated with
reasons of health, recovery, and replacing an inadequate diet. Males
are more likely to report taking supplements for enhanced performance.
Both genders equally rated increased energy as another reason for
engaging in supplement use. Many dietary supplements are highly accessible
to young athletes and they are particularly vulnerable to pressures
from the media and the prospect of playing sport at increasingly elite
levels. Future research should provide more direct evidence regarding
any physiological side effects of taking supplements, as well as the
exact vitamin and mineral requirements for child and adolescent athletes.
Increased education for young athletes regarding supplement use, parents
and coaches should to be targeted to help the athletes make the appropriate
WORDS: Nutrition, sport, adolescent athletes, dietary supplement.
Nutrition is an important aspect of an athlete's training program.
Although exercise and athletic training is considered to increase
nutrient needs in some athletes, a balanced diet with adequate calories
can potentially provide the necessary nutrients (American Dietetic
Maughan et al., 2004).
It is likely, however, that for various reasons, not all athletes
are able to consume a diet that meets their nutritional needs and
thus resort to nutritional supplements with the intention of preventing
deficiencies and even enhancing performance (Maughan et al., 2004).
Today, the supplement industry is an international market worth
billions of dollars. In 2000, it was reported that sales of dietary
supplements in the US reached US$17.1 billion with an annual increase
in consumer spending of more than 10% (Food and Drug Administration,
Although many individuals use supplements, those engaged in sport
and physical activity represent a substantial portion of the population
purchasing supplements (Maughan et al., 2004).
A past review of supplement use among athletes was conducted by
Sobal and Marquart, 1994a,
which analyzed literature, published primarily in the 1980's. With
the supplement market being what it is today, supplements are readily
available to athletes and are more accepted within the athletic
culture, thus investigation into current supplementation behaviours
is warranted. This review will look at the current literature on
supplement use among young athletes, a population particularly vulnerable
to the hype and claims put forth by the supplement industry.
OF SUPPLEMENT USE
to place the current paediatric literature into context it
is necessary to briefly summarise the adult literature. A
major area of the adult research literature regarding athlete
supplement use focuses on athletes at the university or college
level, thus involving athletes over the age of 18 and adult
athletes (Froiland et al., 2004;
Kristiansen et al., 2005;
Sobal and Marquart, 1994a).
A study involving athletes attending a US Division I university
revealed that 89% of the subjects had used supplements or
were using supplements at the time the study took place (Froiland
et al., 2004).
Another study involving US NCAA Division I university student
athletes found that 88% of respondents consumed at least one
nutritional supplement and 58% used two or more supplements
(Burns et al., 2004).
Additionally, Canadian varsity athletes (94.3%) have been
found to use one or more supplements at least once per month
(Kristiansen et al., 2005).
Supplement use among elite athletes is well documented, as
a high percentage of Canadian Olympic athletes were found
to consume dietary supplements at the Atlanta (69%) and Sydney
(74%) Olympic Games (Huang et al., 2006),
77% Singaporean elite athletes reported consuming dietary
supplements (Slater et al., 2003),
and a high prevalence of supplement use was found among competitive
athletes (53%) in the United Kingdom (Airstone et al., 2005).
The population reported to most frequently engage in supplementation
is elite athletes who compete at national, international,
and Olympic levels (Sobal and Marquart, 1994a).
For example, Erdman et al., 2006
found that 88.4% of Canadian elite athletes competing at the
provincial, varsity, national, North American, and international/professional
levels reported taking one or more dietary supplements. All
levels of athletes engaged in supplement use more frequently
during the training phase, however athletes competing at the
international/professional level reported using supplements
most frequently during both training (98.3%)
and competition (87.1%) while provincial-level athletes used
supplements least frequently during both training (89.6%)
and competition (73.6%) (Erdman et al., 2006).
Prevalence of supplement use among young athletes is not as
clearly documented as the adult and elite athlete literature.
There are a limited number of recent studies conducted in
the 1990's and 2000's investigating supplement use by child
and adolescent athletes though the same issues also appear
to be pertinent to this younger age group. Investigating this
particular population is important as studies show that supplement
uses amongst the child and adolescent athlete population is
widespread (see Table 1).
Sample sizes used in the reviewed studies varied substantially
from 32 to 1,355 and the prevalence of supplement use among
child and adolescent athletes ranged from 22.3% to 71% (Table 1). With the exception of the Scofield and Unruh, 2006
study, the larger studies found a lower prevalence rate than
the studies with the smaller sample sizes. This substantial
difference could be the result of the inconsistent methodologies
of the studies thus implying that the prevalence rate may
not be as high as anticipated. Two studies (O'Dea, 2003; Bell et al., 2004) did not look at the overall prevalence of supplement
use and instead focused only on the use of individual supplements,
thus narrowing still the amount of available data on overall
prevalence rates of supplementation practices in young athletes.
Variation also occurred among the ages of the participants
included in the studies. Although the focus was on 'young'
athletes, five studies examined a range of ages (Kim and Keen,
1999; O'Dea, 2003;
Scofield and Unruh, 2006;
Sobal and Marquart, 1994a)
while two studies focused only on a single age (Nieper, 2005;
Ziegler et al., 2003).
Studies also differed in the actual ages included in the studies;
one included subjects as young as 11years (O'Dea, 2003),
others included athletes aged 19 years, and another investigated
high school athletes, reporting grade levels but not actual
ages (Sobal and Marquart, 1994b)
(Table 1). A few recent
studies of elite athletes have included young athletes in
the population sample, however with the exception of Slater
et al., 2003,
the ages included in the studies did not distinguish between
the age groups thus it was not possible to determine the prevalence
of supplement use by the young athletes in the sample. Slater
et al., 2003,
on the other hand, found that 77% of respondents used dietary
supplements within the year previous to the study, however,
no difference was found in relation to age and 53.8% of respondents
were under the age of 20 (Slater et al., 2003).
Such a variance in age could affect the results, as the older
athletes may have more access to supplements and may be more
exposed to supplement use. Dietary intakes of younger athletes
are most likely to be monitored by a parents or guardian and
therefore they would have less freedom to engage in supplement
use compared to older athletes who would have more opportunity
to engage in unsupervised supplement use. The older adolescent
athletes may be pressured by their peers and team mates to
use supplements, and would have easier access to supplements
than their younger counterparts. On the other hand, one study
found that young athletes reported taking supplement because
their mothers gave them to them (O'Dea, 2003) thus suggesting that younger athletes might have little
control over their supplement intake.
The level of competition the subjects engaged in differed
and thus could have had an effect on the prevalence of supplement
use. Five studies (Kim and Keen, 1999; Metzl et al., 2001; O'Dea, 2003;
Scofield and Unruh, 2006;
Sobal and Marquart, 1994b)
investigated supplement use among high school athletes, one
study (Bell et al., 2004)
focused on students enrolled in health and wellness classes,
and two studies (Nieper, 2005;
Ziegler, et al., 2003)
focused on elite-level athletes. Some studies covered a wide
scope of sports, especially those focusing on high school
athletes, where others examined athletes
of particular sports, such as track and field (Nieper, 2005)
and figure skating (Ziegler et al., 2003).
There is also diversity in the type of sport, which the various
participants were engaged in. Athletes involved in multisports
(2 or more sports) tend to engage in supplement use more frequently
than athletes involved in a single sport (Scofield and Unruh,
Two studies included athletes from only specific sports (Ziegler
et al., 2003;
while others explored supplement use across a range of sports.
Supplement use among particular sports, mainly those requiring
athletes to 'make weight' or the more aesthetic sports is
also more prevalent. Sobal and Marquart, 1994b
found that wrestlers (59%) were more likely to use supplements
than others such as softball, hockey, and golf players (each
50%) with gymnasts not far behind (40%).
Also, most studies used questionnaires to investigate supplement
use, however, one study (O'Dea, 2003)
used focus groups and another study (Ziegler et al., 2003)
used anthropometric measures and food records, as well as
OF SUPPLEMENTS USED
these methodological variances a trend emerged which revealed
that the most frequently used supplement among young athletes
is a form of vitamin/mineral supplement. Studies investigating
only vitamin and mineral supplementation (Sobal and Marquart,
Kim and Keen, 1999)
found the most frequent forms of vitamin/minerals consumed
tend to be vitamin C, multivitamins, iron, and calcium (see
Table 2). These results
coincide with a more recent study which also included a range
of what were termed 'ergogenic aids' such as Creatine and
caffeine, and again, the most commonly used supplements by
adolescent athletes were multivitamins, vitamin C, and iron
The supplement list included in the reviewed studies differed
however vitamin/mineral supplements were consistently one
of the most frequently used supplements. A study of adolescent
athletes (Bell et al., 2004)
investigated the use of several supplements which are readily
accessible to adolescents found that in addition to vitamins
and minerals, protein (14%), energizers (6%), and Creatine
(5%) were also consumed. Contradicting these findings are
results from another study (O'Dea, 2003) in which the most frequently used nutritional supplement
was sports drinks (56%), with vitamin/mineral tablets second
(49%), followed by energy drinks (42%), herbal supplements
(18%), guarana and creatine (5%), high protein milk supplements
(4%), and coenzyme Q10 (1%). Ziegler et al., 2003 also found multivitamin/minerals to be the most popular
supplement by both male (61%) and female (83%) adolescent
athletes. To specifically investigate creatine use among young
athletes, Metzl et al., 2001 surveyed middle and high school athletes aged 10 to 18
years and found that 62% reported using Creatine. This usage
is despite recommendations for athletes under the age of 18
not to consume it or any performance-enhancing substance (American
Academy of Pediatrics, 2005).
Although the risks associated with vitamin and mineral supplementation
are not as severe as the risks involved with using ergogenic
aids such as steroids, amphetamines, and human growth hormone,
young athletes could potentially start out using vitamin and
mineral supplements, then progress to more dangerous substances
(Sobal and Marquart, 1994b). Many dietary or nutritional supplements have the reputation
of being harmless because they consist mainly of naturally
occurring compounds and tend to be advertised as safe and
legal performance-enhancing substances as opposed to the banned
substances such as anabolic steroids. Unfortunately, despite
their seemingly 'natural' composition, not all supplements
are tested by the Food and Drug Administration (FDA) therefore
claims of safeness and reliability cannot be trusted (Metzl
et al., 2001). The effects and dosage recommendations of supplements
are also not regulated so there is no guarantee that they
will provide the alleged outcome (Clarkson et al., 2002). Furthermore, taking single vitamins and minerals is
potentially harmful, as large doses can lead to toxicity and
interactions with other nutrients (Kim and Keen, 1999; Maughan et al., 2004; Sobal and Herbert, 1988).
the use of supplements increasing amongst the child and adolescent
athlete population, it is important to investigate the reasons for
the athletes adopting this behaviour. Burns et al., 2004 found that adult athletes reported using vitamin and mineral
supplements frequently and considered them to have the highest impact
on healing/rehabilitation, while protein supplements and Creatine
were considered to have the highest perceived impact on sport performance.
Other reasons for supplement use cited by adult and elite athletes
include increased energy, enhanced performance, improved health,
prevention of nutritional
deficiencies, prevention of illness, increased muscle mass, and
improved recovery (Erdman, et al., 2006;
Froiland, et al., 2004;
Kristiansen, et al., 2005;
Slater et al., 2003).
In the child and adolescent athlete literature, the reasons for
supplementation are similar. High school athletes have reported
growth (48%), illness prevention (44%), illness treatment (37%),
enhanced performance (31%), tiredness (28%), and muscle development
(28%) as the important reasons for consuming supplements (Sobal
and Marquart, 1994b).
Nieper, 2005 found that the primary reasons for UK junior national
track and field athletes to consume supplements included health
(45%), immune system (40%), and performance (25%). Enhancement of
athletic performance is certainly on the minds of adolescent athletes,
as a study conducted by Perko et al., 2000 found that adolescent athletes agreed that most athletes
their age need dietary supplements a) to improve sports performance
(17.7%), b) taking dietary supplements would help all athletes perform
better (27.4%), c) taking supplements is a safe way to improve sports
performance (32.7%), d) that supplements give you more energy (41%),
and e) taking supplements is a good way to build muscle (44.8%).
The influence of elite and professional athletes engaging in supplement
use cannot be ignored. Highly publicized accounts of athletes, who
are idolized by children and adolescents, using supplements and
ergogenic aids may glamorize supplement use and encourage young
athletes to mimic their actions (Calfee and Fadale, 2006).
Young athletes are under great pressure to attain increasingly higher
levels in sport, thus they may be enticed to seek alternative means
to be able play at elite levels or to be noticed by professional
scouts. The high economic value and social status of a professional
athletic career may lure young athletes to engage in supplement
use as a means for developing the competitive edge to 'make it'
as a professional sports person (Calfee and Fadale, 2006).
The desire to play sport at the varsity or collegiate level is another
justification for young athletes to engage in supplement use. Athletes
expecting to play sports after secondary school are more likely
to take dietary supplements (Sobal and Marquart, 1994b). In North America, playing sport at the university or
college level comes at a high financial cost thus the quest to secure
and maintain an athletic scholarship may be another motivator for
using performance-enhancing substances (Calfee and Fadale, 2006). This may also become a factor in the UK, as universities
are beginning to offer sports scholarships to attract and retain
use tends to differ across genders for prevalence of use, types
of supplements used, as well as reasons for use. Specific gender
comparisons are largely confined to three of the reviewed studies,
which explored the percentages of males and females using supplements.
It was found that females engage in supplement use more frequently
than their male counterparts which was consistent with the trend
observed in previous reviews of the literature (Sobal and Marquart,
1994a; Sobal and Muncie, 1988) however in the current review, one study (Scofield and
Unruh, 2006) found conflicting results (see Table
3). The other four original studies included in this review
either accounted for gender differences only in particular aspects
of data analysis (Kim and Keen, 1999; Perko et al., 2000; O'Dea, 2003;
Sobal and Marquart, 1994b),
or compared genders for individual supplements (Bell et al., 2004),
not overall use.
In terms of reasons for supplement use, males tend to put more emphasis
on the athletic performance-enhancing effects of supplements where
as females tend to be more concerned with the health benefits (Slater
et al., 2003;
Sobal and Marquart, 1994b).
confirmed this by revealing that female UK junior national track
and field athletes reported taking supplements for health issues
(33%) and strengthening the immune system (44%) with performance
and strength (both 11%) reported as less important. The primary
reason males consumed supplements was to improve performance (36%)
and males (45%) consumed 'ergogenic aids' (defined as Creatine and
caffeine) more often than females (11%).
Zeigler et al. (2003)
found that male and female elite figure skaters differed considerably
in terms of their motivation for consuming supplements. Females
used supplements to prevent illness (61%), increase energy (39%),
and make up for an inadequate diet (28%). Males used supplements
to increase energy (41%), prevent illness (34%), and enhance performance
(21%). This is evident in the types of supplements used most frequently
used by each gender. Females consumed multivitamin/mineral supplements
most frequently (83%), followed by herbal supplements (48%), and
multivitamin-only supplements (42%). These supplements could be
categorized as health-related supplements, where males also used
multivitamin/mineral (61%) and herbal supplements (44%), they were
taken less frequently, and instead, males consumed protein bars
(38%), protein powders (15%), amino acid powders (8%), and Creatine
(3%) more frequently than their female counterparts, confirming
that males tend to use supplements claiming a more ergogenic effect.
The only exception to this is that females
(35%) consumed energy drinks and bars slightly more frequently than
OF LITERATURE AND FUTURE RESEARCH DIRECTIONS
Several limitations should be acknowledged whilst conducting this
review of the supplement use literature. Most studies included in
this review used a form of questionnaire to assess supplement use
among athletes, however, one study (O'Dea, 2003)
used focus groups, and another (Ziegler et al., 2003)
used a combination of questionnaire and other anthropometric measurements.
The questionnaires used were different, and although addressing
similar matters, subtle differences could affect the overall results.
Another issue in reviewing the literature is that different studies
investigated the use of different supplements in the questionnaires.
For example, some included sports drinks, energy drinks, caffeine,
herbal supplements while others included a few supplements, while
others still focused only on vitamin and mineral supplements. To
achieve an accurate account of the prevalence and frequency of use
of all types of supplements, studies should incorporate a more uniform
method of examining supplement use which would include a uniform
categorization of supplements, as well as a standardized list of
the types of supplements to include in the analysis to enable direct
comparisons between the findings of various studies. This process
would allow researchers to obtain a more complete interpretation
of the current usage of supplements among the young athlete population.
Further research is needed regarding the effects of high toxicity
levels of vitamins/minerals in adolescents, as they are the most
frequently consumed supplement by the population. The nutritional
component of the young athlete's training program is especially
crucial as there are many connections between nutritional deficiencies,
growth, development, athletic performance, and injury prevention
(Petrie et al., 2004).
A major concern for health professionals and the sporting community
is that the effects of supplement use on the growth and development
of children and adolescents are unclear. Minimal experimental research
exists regarding the performance-enhancing qualities or adverse
effects of ergogenic substances focusing exclusively on adolescent
athletes under the age of 18 (American Academy of Pediatrics, 2005).
Many physiological changes are occurring during these developmental
stages thus making it difficult to fully understand the physiological
implications of regular consumption of supplements by this age group
(Calfee and Fadale, 2006).
More direct evidence is also needed regarding potential physiological
side effects of taking any type of supplement.
Another area requiring further research is the exact vitamin and
mineral requirements of child and adolescent athletes. Most of the
research currently available shows that athletes tend to have a
greater food intake that negates any increased need for vitamins
and minerals. The majority of these studies are however, citing
results of studies conducted in the 1980's and 1990's. More current
empirical evidence would be beneficial, as although in theory, the
diets of athletes should be better and more complete than their
non-athletic counterparts, this cannot be assumed. It is quite possible
that that the diets of athletes are not supporting the increased
requirements for vitamins and minerals. Nutrition knowledge of adolescent
athletes has been found to be inadequate and laden with misconceptions
regarding the nutritional requirements for maximal sport performance,
and thus their dietary habits tend to be poor (Reading et al., 1999).
To further investigate the factors influencing athletes to engage
in supplement use, it may be beneficial to explore the link between
health and athletic performance. Although research has demonstrated
that enhancement of sport performance is a primary reason for supplementation,
overall health concerns also emerged as a key motivator, especially
for females, and was often more prominent than sport performance
(Kim and Keen, 1999;
Sobal and Marquart, 1994b).
Vitamins and minerals are considered a nutritional supplement, however,
it is possible that athletes, who are generally concerned about
their health and aware of the impact optimal health has on athletic
performance, view vitamins and minerals as more of a pharmaceutical
or medicine than a supplement. Since vitamin and mineral use is
so prevalent among athletes, it is likely that there is a misunderstanding
as to the role of vitamins and minerals in the diet, their function
in maintaining overall health, their role in athletic performance,
and how they are best obtained from the diet. Athletes want to be
as healthy as possible and tend to consume vitamins and minerals
to maintain health rather than boost performance therefore it may
be advantageous to determine a different approach to studying and
addressing vitamin and mineral use by athletes.
In conclusion, it is important to recognize sporting organizations
such as UK Sport, who are acknowledging the need to educate young
athletes about supplement use. To do this, UK Sport have decided
to focus their efforts on their attitudes and values of supplement
use in sport. UK Sport has commenced a research project involving
over 1,000 young athletes in the UK (UK Sport, 2006).
As well as increased education for young athletes regarding supplement
use, parents and coaches also need to be targeted to help the athletes
make the right choices.
Promoting physical activity in children and adolescents is particularly
important at this time of increasing incidence of childhood obesity.
Instilling a healthy attitude about exercise and sport in youth
is imperative, but the message may become misconstrued if the emphasis
is to excel at all costs, thus suggesting to young athletes that
using supplements is the key to success. Supplement use among young
athletes is a current and substantial issue that merits future study
in order to provide as much accurate information as possible for
both professionals and consumers.
would like to thank the staff at the Children's Health and Exercise
Research Centre, University of Exeter, for their warm hospitality
during my work placement. I would especially like to thank Prof.
Craig Williams for his guidance and support.
use among the child and adolescent athlete population is widespread
with the most frequently used supplement being a form of vitamin/mineral
effects of supplement use on the growth and development of children
and adolescents remain unclear and thus use of supplements by
this population should be discouraged.
is likely that there is a misunderstanding as to the role of vitamins
and minerals in the diet, their function in maintaining overall
health, their role in athletic performance, and how they are best
obtained from the diet therefore further education for adolescent
athletes and athletes in general is needed.
Employment: Dietitian, Nutrition Consultant, Sessional lecturer
for the Department of Family and Nutritional Sciences, University
of Prince Edward Island.
Degree: BSc. (Psychology), BSc. (Foods and Nutrition), MSc.
(Psychological Research Methods), RD (Registered Dietitian).
Research interests: Dietary supplement use, nutrition
knowledge, and disordered eating among young athletes.