effects of trace mineral supplementation, par-
ticularly magnesium, zinc, and copper; while
Clarkson and Haymes (1994) recommend a
multivitamin/mineral supplement containing
no more than the dietary guideline to athletes
whose diets may be less than optimal.
Microminerals: iron
Iron is another mineral worthy of consideration
for supplementation. Deficiency of this mineral
has the distinction of being common in female
athletes and is frequently reported in physically
active populations. In a comparison of 111 adult
female habitual runners with 65 inactive females
of comparable age, Pate et al. (1993) found
serum ferritin levels, indicative of iron status,
28% lower in the runners than controls.
However, frank iron deficiency indicated by sub-
optimal haemoglobin levels was rare in both
groups. Dr Eichner provides insight into the
reasons for iron depletion and expanded discus-
sion of the effect of exercise on this mineral (see
Chapter 24).
Challenges in maintaining adequate iron
stores in the female athlete include the complex-
ity of the mineral’s absorption, lower intakes of
energy by females, low levels of iron in food,
avoidance of meat products, and monthly men-
strual losses. More challenge is added to under-
standing this issue when one needs to decide
which haematological assessment to use for iron
status determination. Lack of standardization of
the blood parameters and values used to classify
the stages of iron depletion lends to the variabil-
ity reported for the incidence of iron depletion in
athletic populations.
However, most agree that iron supplements
are appropriately given to those athletes who
are diagnosed with iron deficiency anaemia
(Haymes 1987). This is related to reports by some
researchers that aerobic capacity in female
athletes with mild anaemia can be improved
with iron supplementation (Fogelholm 1995).
Supplement use by athletes
Sobal and Marquart (1994) reviewed 51 studies
in which 10 274 athletes were investigated
regarding the prevalence, patterns and expla-
nations for their vitamin/mineral supplement
use. Mean percentage of supplement use among
female athletes was 57% (33 study groups).
Several reasons were noted by the athletes for
their supplement use: performance enhance-
ment, prevention of illness, substitute for inade-
quate diet, provision of additional energy, and
the meeting of specific nutrient demands for
exercise. It was also noted that vitamin and
mineral supplements were more frequently used
by female athletes consuming low energy diets.
Small sample sizes (<50 athletes) of most of the
reviewed studies (56%) and the minor focus on
supplements in the studies limits our under-
standing of supplement use by athletes. The
authors recommended that those who study
dietary intake of athletes consider vitamin/
mineral supplement use as an important part
of their study designs and sport nutritionists
include a vitamin/mineral supplement history
as part of their dietary assessment.
If the female athlete consumes adequate
amounts of a variety of foods, she does not
require vitamin/mineral supplementation to her
food intake. However, for those athletes who
consistently restrict energy intake, a one-a-day
multiple vitamin/mineral supplement can
provide some insurance in meeting nutrient
needs for overall good health and exercise.Fluid intake and recommendations
Due to the wide variation in individual fluid
losses during exercise, it is not reasonable to dif-
ferentiate hydration recommendations for the
female athlete. In spite of the physical, phy-
siological and hormonal differences between
males and females, individual variations in
fluid balance surpass any gender differences (R.J.
Maughan, personal communication).Conclusion
Dietary guidelines based on data from sedentary
or male populations pose challenges, as well as
opportunities, for the sports nutritionist and