1. What is chromium?
Chromium is an essential trace mineral that facilitates the action of insulin.
It is found in high amounts in meat, fats, brewer's yeast, and often times
in drinking water. Chromium picolinate is marketed as a supplement that reduces
body fat, increases lean muscle, and improves insulin sensitivity, and is
the second most popular dietary supplement after calcium (1).
2. What application does chromium have?
There are a few studies that make chromium look promising in select individuals.
A study in hyperinsulinemic, obese rats found chromium improved glucose disposal
and lowered cholesterol, while it had no effect on lean rats (2). A human
study on chromium nicotinate as a preventative measure for insulin resistance
in a healthy population found that it lowered immunoreactive insulin (IRI)
in subjects that had high levels of it, although there were no changes in
fasting glucose or lipids (3). Two smaller, unblinded studies found chromium
combined with nicotinic acid to improve glucose disposal and decrease cholesterol
in the elderly and two individuals with high cholesterol, respectively (4,
5).
Many controlled clinical trials have been done to determine if chromium picolinate
has an effect on body composition and athletic performance in various populations,
and all of them have come out negative (6). Additionally, two studies in
elderly populations indicated that supplementation with almost a milligram
a day of chromium increased chromium excretion 50- to 60-fold (7, 8). However,
a recent meta-analysis that pooled ten studies together found a statistically
significant body weight reduction of .4 to 1.8 kg from chromium, suggesting
a possible modest benefit (9).
3. Which form of chromium is best?
Although some studies suggest a benefit on glucose disposal and cholesterol
reduction with chromium nicotinate due to synergism (3-5), three trials with
chromium picolinate found it to have no effect on glucose metabolism or lipids
(10-12). Chromium picolinate is also the most toxic form, although chromium
nicotinate may have toxicity as well (see below), which may make an inorganic
form the best choice for the average individual (6), while chromium nicotinate
may be recommended given a specific condition.
4. What are the risks of chromium supplementation?
Multiple in vitro studies show that chromium picolinate generates hydroxyl
radicals and superoxide anions (two free radicals) leading to lipid peroxidation,
mitochondrial damage, and DNA damage (1, 13-15), with one study showing chromium
nicotinate to cause some of the same problems (15). Inorganic forms such
as chromium chloride do not have the same effect (6, 16). To see if this
effect is only relevant in cell cultures, a rat study was done on tissue
distribution and excretion rate of chromium picolinate and the authors suggested
that chromium supplementation appeared relatively safe (1). However, a later
study by the same authors on fruit flies measured factors such as mutations
and sterility and found chromium picolinate (but not chloride) to have a
significant negative effect (16). There is also a case report of toxic hepatitis
in which chromium polynicotinate supplementation may have played a role (17).
The modest benefit chromium supplementation may have to offer is outweighed
by the potential toxicity. 50-200 micrograms a day can be taken safely, but
the commonly employed high dose chromium supplements containing 400 mcg or
more are not recommended. Chromium deficiency is a concern, but a multivitamin
can safely prevent a deficiency in athletes, as can a healthy diet (18).
If you have any questions or comments regarding this article, please email
dvdtlsn@bulknutrition.com.
No part of this article may be reproduced in any form without the permission of David Tolson or Mike McCandless. 
