Introduction
Trace minerals are required by the body
in very small quantities, generally less than
20 mg · day–1 for healthy adults. Fourteen
essential trace minerals have been identified,
but only six are related to exercise, and these
are iron, zinc, copper, selenium, chromium
and vanadium. Vanadium is known to be
essential for animals and is likely essential for
humans, although not enough information
exists to establish a requirement. Boron has
been associated with bone health and exercise,
but it is not yet considered an essential trace
element.
The reason these minerals have received atten-
tion in the sports medicine arena is that
some, like zinc, serve as components of enzymes
involved in energy production, and others, like
selenium and copper, work with enzymes
and proteins that function as antioxidants.
Chromium and vanadium have been purported
to increase muscle mass because they are
involved in either amino acid uptake or growth.
Moreover, there is concern that many athletes
may not ingest sufficient quantities of certain
trace minerals to meet possible losses in sweat
and urine induced by exercise.
This paper will discuss physiological function,
dietary intake and status of athletes, changes
induced by exercise and training, and effects of
supplementation for each trace mineral men-
tioned above (except iron, which is discussed in
Chapter 24).
Zinc
Zinc functions as a component of more than
200 enzymes which affect many processes of
life (Hunt & Groff 1990; Lukaski 1997). The rec-
ommended dietary allowance (RDA) is set at
15 mg · day–1 and 12 mg · day–1 for males and
females, respectively, 11 years and older (Food
and Nutrition Board 1989). Diets containing
meat generally provide sufficient amounts of
zinc to meet the RDA. Animal products, such as
meat, fish, poultry and especially oysters,
contain the most zinc.
Most, but not all, male athletes and some
female athletes ingest sufficient amounts of zinc
(Lukaskiet al. 1983, 1990; Peters et al. 1986; Singh
et al. 1989; Fogelholm et al. 1991, 1992a, 1992b),
but many female athletes do not (Deuster et al.
1986, 1989; Nieman et al. 1989; Steen et al. 1995).
Lower zinc intakes have been reported for female
compared with male swimmers (Lukaski et al.
1990, 1996b). Those athletes maintaining low
body weights, such as wrestlers, dancers and
gymnasts, do not appear to meet their require-
ment for zinc (Benson et al. 1985; Loosli et al. 1986;
Steen & McKinney 1986).Zinc status and effects of exercise
Zinc status is most commonly assessed in serum
or plasma samples, although this measurement
can be affected by stress, infection and oral con-
traceptives (Hunt & Groff 1990). Several studies
reported that male athletes and some female ath-