supplements, and vitamin and mineral supple-
ments. For example, ferrous sulphate tablets
consumed by an iron-deficient female athlete or
a concentrated carbohydrate beverage ingested
following training would be considered dietary
supplements.
Nutritional ergogenic aids encompass those
products whose ingestion is purported to
directly and immediately provoke an improve-
ment in performance. Burke (1992) suggests that
these supplements are better labelled as ‘pro-
posed ergogenic aids’ because there is scant sci-
entific support for their effectiveness. Bee pollen,
ginseng, vanadium, inosine, molybdenum, car-
nitine and countless other pills, potions and
powders appear to fall neatly into this category.
Upon further examination, however, the distinc-
tion between dietary supplements and nutri-
tional ergogenic aids can become blurred. When
carbohydrate is ingested during exercise, is it
meeting a special dietary need or provoking an
immediate improvement in performance? Some
would argue that it does both.
Butterfield (1996) suggested that sports nutri-
tion products could be categorized into four
areas:
1 Metabolic fuels such as carbohydrate, fat and
metabolic intermediates including pyruvate,
lactate and components of the Krebs cycle.
2 Limited cellular components such as creatine,
carnitine, vitamins and free amino acids.
3 Substances with purported anabolic effects
such as energy, protein, chromium and
vanadium.
4 Nutrients which enhance recovery, including
fluid, carbohydrate and electrolytes.
This categorization system allows for pigeon-
holing supplements on the basis of functionality,
although some nutrients serve multiple func-
tions. For example, carbohydrate could fit
equally well in all four categories: as a metabolic
fuel, as a limited cellular component (during the
latter stages of prolonged exercise), as a nutrient
that provokes anabolic effects (via insulin) and as
an aid to recovery.
Kanter and Williams (1995) suggested that the
purpose of most nutritional ergogenic aids is to
enhance energy production during exercise by
either (i) providing an additional energy source
(as in the case of carbohydrate and fat) or (ii) by
benefiting the metabolic processes that produce
energy (a catch-all category for protein, amino
acids, vitamins, minerals and sundry other sub-
stances touted to improve performance). This
two-tiered approach to categorizing sports nutri-
tion supplements served the authors well in their
review of antioxidants, carnitine and choline
(Kanter & Williams 1995), but falls short of pro-
viding a niche for supplements with a proposed
effect on processes other than energy metabo-
lism (e.g. amino acids, chromium, choline, g-
oryzanol).
In the not too distant future, it is likely that
government agencies will attempt to establish
regulatory control over the nutritional supple-
ment industry, including what might be broadly
classified as sports foods. In fact, such regula-
tions have either been proposed or enacted in the
United States, Australia, Japan and within the
European Community. The likely result of each
attempt will be the creation of a less than perfect
way to define and categorize a group of foods,
beverages and supplements that by their very
diversity defy a simple manner of categorization.
None the less, faced with the challenge of
addressing the role of sports nutrition supple-
ments, the following section provides an admit-
tedly arbitrary attempt at organizing the wide
array of sports nutrition supplements into cate-
gories that allow for some degree of generaliza-
tion regarding their proven or purported effects.Role of sports nutrition products
The reader wishing a comprehensive review of
the science underlying sports nutrition products
is referred to the other chapters in this book and
to the many review articles and books previously
written on this topic.Fluid replacement beverages
(i.e. sports drinks)
Sports drinks are the most comprehensively