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NUTRITION SUBSPECIALTY ARTICLE
Use of dietary supplements and hormones in adolescents:
A cautionary tale
Harvey J Guyda MD
HJ Guyda. Use of dietary supplements and hormones in
adolescents: A cautionary tale. Paediatr Child Health
2005;10(10):587-590.
Ergogenic aids, such as nutritional supplements, anabolic steroids and
human growth hormone, are increasingly being used to enhance sports
performance or body image. While few rigorous scientific studies have
derived significant conclusions, the marketing and promotion of most
supplements is intense and far exceeds the data supporting their use.
Particular concern has arisen regarding safety in the use of these substances among adolescents, who may be at particular risk when using
caffeine-ephedra and anabolic steroid combinations. Indeed, long-term
effects and fatalities have been reported. As a consequence, the
American Academy of Pediatrics has condemned the use of anabolic
steroid use for bodybuilding or performance enhancement in adolescents. Health care professionals need to educate themselves about
ergogenic use and ask informed questions of their adolescent patients.
An honest discussion of the limitations of most supplements, and
acknowledgement that some supplements may work some of the time,
may allow the physician to be more credible and useful in providing
medical care and guidance to the adolescent seeking to improve body
image or athletic performance.
Key Words: Adolescents; Anabolic steroids; Dietary supplements;
Human growth hormone
‘NUTRITIONAL’ SUPPLEMENTS
The field of nutritional supplementation for ergogenic benefit is complex and rapidly changing. Natural health products do not require a prescription and are available for
self-care and self-selection. It is important to note that the
number of studies with rigorous scientific methodology that
have derived significant conclusions is small, whereas the
intensity of the marketing and promotion of most nutritional supplements is intense, far exceeding the data supporting their use (1). The most common supplements
currently used are amino acids, creatine, protein powder,
caffeine, ephedrine-type alkaloids (derived from the herb
ma huang), ginseng, vitamin C, vitamin E, multivitamins,
copper, magnesium and zinc (Table 1). Many supplements
are marketed and promoted on the basis of various theoretical benefits that may be derived from limited animal studies, without any proven basis for recommending their use
by humans for specific ergogenic benefits. Approximately
Le recours aux suppléments diététiques et
aux hormones chez les adolescents :
Un avertissement
Les aides ergogéniques, telles que les suppléments diététiques, les stéroïdes
anabolisants et les hormones de croissance humaines, sont de plus en plus
utilisées pour améliorer les performances sportives ou l’image corporelle.
Peu d’études scientifiques rigoureuses ont tiré des conclusions
significatives à ce sujet, mais la commercialisation et la promotion de la
plupart des suppléments sont intenses et dépassent de loin les données à
l’appui de leur usage. Des préoccupations particulières ont été soulevées
au sujet de l’innocuité de ces substances chez les adolescents, qui sont
particulièrement à risque s’ils utilisent une association de caféine éphédra
et de stéroïdes anabolisants. En effet, des effets à long terme et des décès
ont été déclarés. Par conséquent, l’American Academy of Pediatrics a
condamné le recours aux stéroïdes anabolisants pour le culturisme ou
l’amélioration des performances chez les adolescents. Les professionnels
de la santé doivent se tenir au courant de l’usage d’aides ergogéniques et
poser des questions informées à leurs patients adolescents. Une discussion
honnête sur les limites de la plupart des suppléments et l’admission que
certains suppléments peuvent parfois fonctionner peuvent permettre au
médecin d’être plus crédible et plus utile dans ses soins et ses conseils
médicaux à l’adolescent qui cherche à améliorer son image corporelle ou
ses performances athlétiques.
50% of the general population and up to 100% of athletes
in some sports have reported taking some form of dietary
supplement (1,2).
Dietary supplements are not required to meet the United
States Food and Drug Administration requirements (3), but
Health Canada has established new guidelines for over-thecounter products (4). Natural health products are defined in
Health Canada regulations as vitamins and minerals, herbal
remedies, homeopathic medicines, traditional medicines
(such as traditional Chinese medicines), probiotics, and
other products such as amino acids and essential fatty acids.
Under the new regulations, the product must be safe for consideration as an over-the-counter product. It is important to
note that nonhormonal supplements, such as vitamins, minerals and amino acids, may contain anabolic steroids that are
not declared on the labels of the products (5).
Very few studies have examined the performance benefits
of long-term, nonanabolic supplement use (1,2). A frequently
Department of Pediatrics, McGill University, and Montreal Children’s Hospital, Montreal, Quebec
Correspondence: Dr Harvey J Guyda, Department of Pediatrics, Montreal Children’s Hospital, Room C-414, 2300 Tupper Street, Montreal, Quebec
H3H 1P3. Telephone 514-412-4467, fax 514-412-4251, e-mail [email protected]
Paediatr Child Health Vol 10 No 10 December 2005
©2005 Pulsus Group Inc. All rights reserved
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cited study (6) performed at the Australian Institute of Sport
comprised 82 elite athletes in four sports – basketball, gymnastics, rowing and swimming. Athletes were randomly
assigned in a controlled, blinded fashion to their usual diet
or a diet with a markedly enhanced intake of vitamins and
minerals – 10 to 50 times the recommended daily intake of
vitamins A, B1, B2 (riboflavin), B6, B12, C, E, folate, calcium,
phosphorus, aluminum, copper, magnesium and zinc.
Athletes were followed for up to eight months to assess performance and side effects. Athletes on the supplemented
diet had significantly increased blood levels of several vitamins, but no benefit to athletic performance was seen.
Concern has arisen regarding the safety of the use of
performance-enhancing substances in adolescents (7-10).
Few safety studies of supplements have included adolescents, who may be at particular risk when using caffeineephedra and anabolic steroid combinations. In a study (7)
of 742 high school athletes, 38% used supplements. The
most common reasons given by the athletes for nutritional
supplement use were to promote healthy growth, prevent
illness and improve performance. Sixty-two per cent
believed that supplement use improved athletic performance (7). The variety of supplements used may have significant implications for the medical care of adolescents
(Table 1), who do not regularly inform their physicians
about their use. Health care professionals need to educate
themselves about supplement use and ask informed questions to their adolescent patients (8-10).
ANABOLIC STEROIDS
In response to the controversy over the use of anabolic
steroids (2,11-13), the American Academy of Pediatrics has
condemned their use for bodybuilding or performance
enhancement in adolescents (12). However, abuse of anabolic steroids, such as androstenedione and dehydroepiandrosterone, to increase muscle mass is a serious
problem not only among professional athletes but also
among bodybuilders and teenagers (12). Among high
school students, 3% to 12% of males and 1% to 2% of
females admit to anabolic steroid use at some time (13).
Long-term effects and fatalities due to anabolic steroid
abuse have been reported, including liver tumours, myocardial infarction, stroke and severe arteriosclerosis (Table 1).
A significant black market has been established in the gym
culture, but studies of anabolic steroids bought on the black
market have shown that 35% do not contain the expected
ingredients (11).
HUMAN GROWTH HORMONE
Human growth hormone (HGH) has a number of accepted
medical uses due to its anabolic effect on protein metabolism, but it has become a popular ergogenic aid among athletes (2,14). The supraphysiological effects of HGH lead to
lipolysis, with increased muscle volume (14). HGH may
also be used for its anabolic effect, but data on this effect
are lacking in adolescents. Due to the ethical limitations
588
of studying the use of high doses of HGH in isolation or
combined with anabolic steroids, the scientific literature
has not produced compelling results on its efficacy. HGH
has led to some improvement in athletic performance in
isolated studies (2,14). Despite the lack of compelling data,
HGH has developed a reputation among athletes for
enhancing performance (2,14).
PROGRAMMED INTERVENTION:
INNOVATION LEADING TO IMPROVED
ADOLESCENT HEALTH
An innovative prospective controlled trial (15) of 18 high
schools, including 928 students from 40 participating sports
teams, was designed to prevent young female high school
athletes’ disordered eating and body-shaping drug use.
Balanced random assignment was used to assign the schools
to the intervention (eight weekly 45 min sessions) or to
usual-care control conditions. Experimental athletes
reported significantly less ongoing and new use of diet pills,
and less new use of performance-enhancing substances
(amphetamines, anabolic steroids and sports supplements).
Other health-harming actions were also reduced (eg, fewer
instances of riding with an alcohol-consuming driver, more
seat belt use and less new sexual activity). The experimental athletes had coincident positive changes in strengthtraining self-efficacy and healthy eating behaviours. Thus,
sports teams can be effective natural vehicles for peer-led
curricula to promote healthy lifestyles in adolescents and to
deter disordered eating, performance-enhancing substance
use and other health-harming behaviours.
CONCLUSIONS
Amateur and professional athletes use numerous ergogenic
aids that claim to enhance sports performance. Although
some studies have indicated a performance benefit in particular athletic situations, there are few available data
regarding efficacy or safety in competitive or noncompetitive adolescents (8-14). Common ergogenic aids include
nutritional supplements, anabolic steroids and HGH.
Physicians can evaluate these products by examining four
factors that can help them counsel their adolescent
patients: method of action, available research, adverse
effects and legality. However, athletes report that their most
common sources of dietary and supplement information to
be (in rank order) their trainer or coach, a family member
or friend, magazines and books, a physician and a nutritionist (1). While most adolescents may not seek information
about ergogenic benefits from medical professionals, they
may seek information about side effects or contraindications if the physician is open and nonjudgemental. An
honest discussion of the limitations of most supplements,
and acknowledgement that some supplements may work
some of the time, may allow the physician to be more credible and useful in providing medical care and guidance to
the adolescent seeking to improve body image or athletic
performance.
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Use of dietary supplements and hormones in adolescents
TABLE 1
A paediatrician’s glossary of ergogenic aids
Ergogenic agent
Purported actions
Proven effects
Side effects
Amino acid
Increases exercise-induced HGH release
Pre-exercise oral amino acid
Large doses cause stomach discomfort
mixtures: arginine,
via oral ingestion.
lysine, ornithine
supplementation does not augment
and diarrhea.
HGH release. No increased exercise
benefit above exercise alone.
Anabolic steroids:
androstenedione,
Improves muscle mass and strength
beyond inherent genetic limits.
dehydroepiandro-
Few studies of how DHEA affects anabolic
Long-term use associated with liver tumours,
activity in younger athletes whose
severe arteriosclerosis, myocardial
levels are already very high.
infarction, stroke and premature death
sterone (DHEA)
due to severe tissue-damaging effects,
some of which are irreversible.
Arginine
Needed for periods of growth and recovery
after injury; precursor for protein,
but lower doses do not increase
creatine and nitric oxide biosynthesis;
HGH release and may even impair
increases HGH release.
Carnitine
Very high intakes may increase HGH levels,
Improves skeletal muscle function and
athletic performance in healthy individuals.
None at usual doses.
HGH release in younger adults.
No compelling evidence that carnitine
Oral carnitine doses of several grams
supplementation improves physical
cause no significant clinical toxicity.
performance in healthy subjects.
Chromium
Promoted as a nonsteroidal anabolic
hormone to increase lean body mass.
No specific ergogenic effect has been
demonstrated.
Interferes with iron and zinc metabolism;
addition of ephedrine to chromium can
cause hypertension, stroke and death.
Copper
Creatine
Ginseng
Critical nutrient.
Provides increased power during
No studies have demonstrated a specific
ergogenic effect from supplementation
GI distress, nausea, vomiting and diarrhea,
beyond usual dietary intake.
as well as intravascular hemolysis.
No benefit on endurance exercise or
anaerobic, short-duration, high-intensity
maximal oxygen uptake. Not tested in
activity.
those younger than 18 years.
Increases resistance to catabolic effects of
Excessive supplementation can cause
None of the proposed mechanisms of action
Significant negative effects, mostly
GI cramping and distress.
Bioavailability may be low, with no active
exercise, with a secondary consequence
have been proven, nor have the benefits
ginseng in some products. Excess leads
of prolonged time to exhaustion with
been demonstrated.
to hypertension, insomnia, diarrhea and
extreme exercise.
irritability, but all or some of these effects
may be due to coexistent ephedrine or
ma huang.
Glucosamine
Regenerates cartilage and aids joint
No direct evidence that repair or protection
In North America, glucosamine is a highly
lubrication and shock absorption,
occurs in vivo, or that the use of
purified derivative of shellfish, which may
and has anti-inflammatory effects.
glucosamine sulfate changes articular
provoke allergic reactions.
cartilage either structurally or functionally.
Magnesium
Increases physical power through
There is no proven effect on performance.
vomiting, diarrhea, muscle weakness
associated increase in aerobic power
and interference with the absorption
and endurance.
Multivitamins:
A and D, B complex,
Excessive intake causes GI upset, nausea,
increased muscle mass, with an
Helps meet increased requirements of
of all or some of these vitamins for up to
resorption and bone abnormalities.
may include many
nine months did not improve aerobic
Hypervitaminosis D causes anorexia,
minerals
performance. Can address dietary
nausea, vomiting, constipation,
Ornithine
intense exercise and training.
of calcium.
10 to 50 times the recommended daily intake Hypervitaminosis A may cause bone
Promotes muscle building by increasing
levels of anabolic (growth-promoting)
deficiencies due to calorie restriction
weakness and weight loss. Both cause
or high carbohydrate intake.
hypercalcemia.
Most human research does not support
these claims at reasonable intake levels.
Very high amounts cause many GI side
effects.
hormones such as insulin and HGH.
Vitamin E
Reduces delayed-onset muscle soreness
in eccentric exercise.
There is no known benefit at low-altitude
exercise, and no performance improvement
Can act as an anticoagulant and may
increase the risk of bleeding problems.
or effect on VO2 max in endurance athletes.
Zinc
Increases muscle contraction strength,
explosive power and power endurance.
No evidence of a measurable ergogenic
effect in controlled studies.
Can cause copper deficiency and interfere
with tetracycline activity.
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TABLE 1 (continued)
A paediatrician’s glossary of ergogenic aids
Stimulant
or narcotic
Purported actions
Proven effects
Side effects
Amphetamines,
Stimulates exercise performance.
May increase time to exhaustion by masking
Anxiety, tremor, tachycardia and hypertension.
the physiological response to fatigue, but
Can increase blood glucose and lactate.
ephedrine
have not been shown to result in any
significant performance improvements.
Caffeine
Stimulates exercise performance.
The potential benefits of caffeine are lost in
Anxiety, tremor, tachycardia and hypertension.
several confounding variables. Most studies
High caffeine intake may accelerate bone
show minimal to no benefit in untrained,
loss. Combinations of caffeine with other
recreational athletes. Caffeine plus
stimulants (eg, ephedrine) have been
ephedrine may increase performance during
linked to fatal events.
submaximal steady-state aerobic exercise.
Narcotic analgesic
Allows extension of exercise
Not necessarily ergogenic.
Harmful if used to allow participation of an
Marijuana does not increase strength. Cocaine
Addictive and illegal.
performance.
Marijuana, cocaine
Enhances athletic performance.
athlete with a severe injury.
and other sympathomimetic drugs have
little or no effect on athletic performance.
GI Gastrointestinal; HGH Human growth hormone; VO2 max Maximal oxygen consumption. Data from references 1 to 3
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