. 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