Negative effects of
chromium supplementation
Because chromium has a low absorption rate,
it is not considered to be toxic (Anding et al.
1997). However, Stearns et al. (1995a) reported
that chromium picolinate produced chromo-
some damage in isolated cells in vitro. This study
received criticism due to its use of supraphysio-
logical doses in cell cultures rather than oral
doses in animals or humans (McCarty 1996). In a
second report, Stearns et al. (1995b) employed a
pharmacokinetic model to predict how ingested
chromium could accumulate and be retained in
human tissue. These authors cautioned against
taking supplements with concentrations greater
than the ESADDI and concluded that the normal
dietary intake of chromium may be adequate to
maintain a positive chromium balance in most
people, even at levels of ingestion somewhat
below the 50–200mg range.
Other anecdotal accounts, case histories and
studies suggest that chromium supplements
may cause headaches, sleep disturbances, mood
changes, increased excretion of trace minerals,
altered iron metabolism and changes in percep-
tual processes (Lefavi et al. 1992; Trent &
Thieding-Cancel 1995). Lukaski et al. (1996a)
found that chromium supplementation for 8
weeks resulted in a small decrease in trans-
ferrin saturation which was greater for the
chromium picolinate supplement than the
chromium chloride supplement. This may be
due to the fact that chromium competes with iron
for binding on transferrin. Lukaski et al. (1996a)
speculated that chromium supplementation may
predispose an individual to iron deficiency.
However, it should be noted that the change in
transferrin saturation was not statistically
significant, thus further studies are needed to
confirm this finding.
Summary
Exercise can increase urinary excretion, as can
ingestion of simple sugars; however, whether
this will induce a chromium deficiency or
whether athletes are able to increase efficiency or
retention of chromium is not known. Because
the long-term safety of chromium is a concern
(Anding et al. 1997), athletes should ingest
foods rich in chromium. For added assurance,
a multivitamin-mineral supplement containing
between 50 and 200mg of chromium would not
be harmful. Studies of the effects of chromium
supplementation on lean body mass in athletes
show that it is not effective. Results of the two
studies to assess chromium’s efficacy as a weight
loss agent are equivocal. Chromium may only be
effective in individuals with impaired status, but
this has not been assessed.Vanadium
Vanadium, like chromium, is purported to have
an insulin-like effect and promote the transport
of amino acids into cells. Because this effect is
thought to be anabolic, vanadium, in the form of
vanadyl sulphate, is widely marketed to body-
builders. There is not sufficient information to
state that vanadium is an essential element for
humans (Food and Nutrition Board 1989). Data
suggesting that vanadium may be anabolic come
from in vitrostudy of cells and pharmacological
studies of animals (Nielsen 1996). For example,
growth rate is reduced in vanadium deficient rats
(Nielsen 1996). The Food and Nutrition Board
(1989) came to the conclusion that if nutritional
requirements exist they are low and easily met by
levels naturally occurring in foods.
Fawcettet al. (1996) cite anecdotal evidence
that athletes are taking up to 60 mg · day–1for
2–3 months to increase muscle mass. In the only
study to evaluate vanadium supplements,
Fawcettet al. (1996) had subjects ingest 0.5 mg ·
kg–1· day–1of vanadyl sulphate or placebo for 12
weeks during a weight training programme.
The results showed no beneficial effect of the
supplement on body composition as assessed by
anthropometric measures or DEXA scans.
Vanadium supplements could have detrimental
effects when taken for a long period of time, but
this has not been adequately studied (Moore &
Friedl 1992). There is no basis at this time to