Sport Food Supplements –
(how) do they work ?
Prof. Renger Witkamp
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There is a lot…
104,000,000 hits in Google !
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76 pills per day, or almost 1600 in three weeks
“If you want to survive the Tour the
France you really need these things”
Quote from
2008…..
(nothing
yet about
EPO)
3
“ non-nutritional”
ergogenic aids and
doping
supplements
Dietary
supplements
sport-specific
nutrition
basic nutrition
4
Food supplement (dietary supplement) :
 “foodstuffs the purpose of which is to supplement the
normal diet and which are concentrated sources of
nutrients or other substances with a nutritional or
physiological effect, alone or in combination,
marketed in dose form, namely forms such as
capsules, pastilles, tablets, pills .. etc ”
 Regulated as foods in most countries (some may
legally be regarded as medicinal products)
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(lean-) body
weight, fat mass
Joints etc
endurance
Nutrient
availability
recovery
power
Sleep
prevention of
disease
ability to train
mental factors
alertness
concentration etc.
Rewarding
& well-being
6
Ergogenic aid (in a broader sense):
 ……any nutritional, physical, mechanical,
psychologic or pharmacological method or aid to
improve physical work capacity or athletic
performance……
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Why do athletes take supplements ?
• Because they’re told to do so !
•
• Personal testimonials
• Coaches and trainers
• Advertisements
Because they belief it helps
• To improve performance
• To prevent illnesses
• To compensate for extra demands during intense
training
• Because competitors use them
• As compensation for an inadequate diet
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9
Lots of hypes and trends (just 1 example)
O
S
O
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Main classes* and examples







Metabolic fuels (carbohydrate, lactate, fat)
Metabolic aids (bicarbonate, beta-alanine, HMB)
Proteins and amino acids
Vitamins and anti-oxidants
Minerals (including trace elements)
Substances that enhance recovery (fluids, electrolytes)
Others : caffeine, supplements for joint health, natural pain
killers and anti-inflammatory compounds, probiotics, colostrum
etc.
* different ways of classification possible
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Caffeine : evidence-based
• Has shown beneficial effects in different types of sports
(endurance, stop-and-go types, high intensity)
• Effects on “acute / single event” types of sport less clear
• Moderate doses effective (few cups of coffee..)
• Indirect effects should also be considered
Example : Rowers' performance in 2,000-m efforts can
improve by ∼2% with 6 mg/kg BM caffeine
supplementation (Carr et al., IJSNEM, 2011)
12
Recent example…
The present study illustrates that both
caffeine (5 mg/kg/BW) and coffee (5
mg/kg/BW) consumed 1 h prior to exercise can
improve endurance exercise
performance.
13
Creatine
• Nitrogen containing endogenous substance (liver,
pancreas, kidneys)
• Precursor of creatine-phosphate (phosphocreatine)
• Topselling product (many tons per year)
• Works in short and intense bursts of strenght (and
speed)
• Not recommended for long distance etc. May keep
water, increase weight
• Aids production of phospho-creatine
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Effects in sports:
•
Improvement in short bouts of activities that
require high levels of strength and power
•
Possibly beneficial to preventing injury
•
Not effective for enhancement of endurance
activities
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Effects:
•
•
•
•
•
Buford et al* : “most effective ergogenic product currently
available to athletes”
20 to 25 g / day creatine increases muscle content of
creatine by 20% to 30%.
A plateau is reached by using 5 g creatine, 4 times a day
for 5 to 6 days (loading phase), followed by a maintenance
(postloading) phase of 2-3 g / day.
Buford et al* : 3 days 0.3 gram/kg/day as loading dose,
followed by 3-5 gram/day (see also Book)
But for field hockey ? No consensus (but use reported in
team sports, lower doses)
* J int soc sports nutrition 2007
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Side-effects :
•
•
•
Weight gain (1-2 kg, rapid) (disadvantage in
endurance athletes and in continuous- type
exercise interspersed with high- intensity
exercise (e.g., football, basketball, etc).
Muscle cramps (sometimes)
GI disturbances
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The youngest kid on the block
Kelly et al (March 2013, online) “ dietary nitrate
supplementation improved endurance during
severe-intensity exercise in recreationally-active
subjects without significantly increasing either
the critical power or curvature constant”
18
Dose-effect relation of a nutrient
homeostasis
Dose
19
More is not automatically better;
sometimes even worse…
PNAS 2009
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Pharmacological dose-effect relation
Dosis
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The Future : towards
personalized sports nutrition
and supplementation ?
Resistance exercise stimulates a prolonged elevation of muscle
protein synthesis (MPS) that can remain elevated for ≥ 24 h (dashed
lines).
22 Churchward-Venne et al. Nutrition & Metabolism 2012 9:40
Take home messages
 Nutritional supplements: sometimes useful
 Ergogenic supplements: caffeine (the rest ?)
 Use supplements under dietary supervision
 Beware of contamination
 Miracles don’t exist (for the time being)
 Science in sports nutrition is moving…
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