Introduction
Nearly all living things need iron, the fourth
most abundant element on Earth. In humans, the
nutritional need for iron centres on its role in
energy metabolism. Iron is necessary for the
formation of haemoglobin and myoglobin, the
oxygen carriers in red blood cells and muscles,
respectively. Iron is also a constituent of several
enzymes—including catalase, peroxidase, and
succinate dehydrogenase—and of the cyto-
chromes, which enable electron transport in cel-
lular respiration (and foster drug metabolism in
the liver). In other words, because it delivers
oxygentocells and facilitates the use of oxygen
bycells, iron is essential for energy metabolism.
Simply put, iron is as vital as oxygen in convert-
ing chemical energy from food into metabolic
energy for life.
Because it is vital for energy metabolism, iron
is critical in sports nutrition. Concerns include:
(i) whether athletes need more iron than non-
athletes; (ii) the prevalence of iron deficiency
among athletes; (iii) the effect of iron deficiency
anaemia on athletic performance; (iv) whether
low ferritin level in the absence of anaemia
impairs performance; (v) how to ensure that ath-
letes—vegetarian or not—get the iron they need
from their diet; and (vi) the pros and cons of iron
supplementation for athletes.
Iron deficiency may be the most common
nutritional deficiency in the world. When it leads
to anaemia, the paramount problem for athletes
is diminished exercise capacity. Iron deficiency
may also impair two other functions key to ath-
letes—immunity and cognition (Dallman 1982;
Cook & Lynch 1986; Bruner et al. 1996)—but
because supporting evidence is limited and
inconclusive, these areas will be omitted here.
The value of dietary iron has been known for
centuries. It is said the Persian physician Melam-
pus in 4000 bcgave iron supplements to sailors
who bled in battle. Other accounts of iron as
therapy date to ancient Egypt and Rome. In the
16th and 17th centuries, poets, painters and play-
wrights portrayed the ‘green sickness’, or chloro-
sis, and attributed it to unrequited passion, or
‘lovesickness.’ Shakespearean heroines and
heroes, disappointed by love, were smitten by
the green sickness (Farley & Foland 1990). It was
Thomas Sydenham in 1681 who first cured the
green sickness with iron; he prescribed a syrup
made by steeping iron filings in cold Rhenish
wine (London 1980).
The symptoms of the green sickness—dysp-
noea, fatigue and palpitations—are recognized
today as those of anaemia. But the grave olive
pallor that gave the condition its name is no
longer common because today anaemia is diag-
nosed early, especially in athletes. Indeed, today
‘anaemia’ is found so early among athletes—and
vague ‘fatigue’ often ascribed to it—that iron
deficiency is sometimes overdiagnosed and
overtreated. Today, we have the Humpty-
Dumpty problem.
Humpty Dumpty, when challenged by Alice
on word usage, said, ‘When I use a word, it
means just what I choose it to mean, neither more