Theory:
Chromium deficiency is known to lead to glucose intolerance and insulin resistance – symptoms commonly encountered in people with diabetes. Since chromium helps regulate the actions of insulin (as a constituent of glucose tolerance factor), chromium supplements may help support the many functions of insulin in the body, such as maintaining blood sugar and cholesterol levels and controlling appetite (particularly sweet cravings). Chromium is notorious for its poor absorption by the body, so many supplements are typically combined with another, more efficiently absorbed compound such as a vitamin (like niacin in polynicotinate versions) or an amino acid derivative (like picolinic acid, a derivative of tryptophan, in picolinate versions).
Scientific Support:
Chromium supplementation rapidly gained popularity the mid 1980s when studies suggested chromium supplements (200mcg per day) were associated with anabolic effects (increased muscle mass and reduced body fat). Subsequent studies have been equivocal on the effect of chromium on muscle and fat mass – with nearly a 50/50 split between studies showing a beneficial effect of the supplements with those showing no effect. Some of the “positive” studies have been criticized for using inaccurate or imprecise measures of body composition to arrive at their conclusions that chromium is beneficial for weight loss.
What we DO know about chromium is that deficiency results in insulin resistance that can be easily corrected by supplements. Chromium deficiency is not unknown in the United States and is thought to contribute to insulin resistance in many people. It is estimated that 90% of Americans consume less than the recommended amount of chromium each day. Also, the urinary excretion of chromium is known to increase in people who exercise, suggesting that active people and athletes may have higher dietary requirements for chromium.
In diabetic and overweight individuals, chromium supplements have been shown to reduce triglyceride levels by almost 20%, improve glucose tolerance and normalize insulin levels. Supplements of 400 mcg have helped overweight women lose about 50% more fat in 3 months compared to a placebo group.
Safety:
Although the vast majority of studies of chromium supplementation reveal no side effects except mild gastrointestinal upset, they tend to be of short duration (a few weeks to a few months). Recent anecdotal reports, however, have suggested a variety of adverse side effects such as anemia, memory loss and DNA damage – in most cases for a particular form of chromium known as chromium picolinate
A handful of laboratory studies have shown that the supplemental form of chromium (chromium III) provided as the picolinate form, causes DNA breakage in isolated cells. Such DNA effects are thought to lead to genetic mutations and cancer, but it is important to note that these cell studies in the test tube are a long way removed from the case of a human ingesting an essential trace mineral. In one of the most publicized studies, Dartmouth researchers demonstrated that chromium picolinate is absorbed into cells intact (at least in the test tube), where it appeared to cause breaks in chromosomal DNA in hamster ovary cells (a common model for cancer researchers). The upshot of the study was that other chromium salts, such as nicotinate and chloride, were not taken up into the cells as efficiently as the picolinate version.
There have been a few case reports of adverse effects following high dose chromium supplementation. In one, a 24-yr-old female body builder developed rhabdomyolysis, a serious condition causing muscle and kidney toxicity, after ingesting 1200 mcg of chromium picolinate over 48 hours. This is 6-24 times the daily recommended allowance of 50-200 mcg. Another case of toxicity following chromium picolinate ingestion (1200-2400 mcg for 4-5 months) involved a 33-yr-old woman who was taking it to enhance weight loss. The supplement increased blood chromium levels to 2-3 times normal and caused anemia, blood abnormalities, liver dysfunction, and renal failure.
Both case reports demonstrate the fact that intakes of chromium picolinate at levels above the recommended dosage should be avoided. An animal study conducted by the USDA, fed rats a diet rich in chromium picolinate for 24 weeks and found no adverse side effects and there are no clinical studies that show harmful effects in humans from supplements containing chromium picolinate. It would seem prudent, however, to avoid excessive intake of supplements containing chromium picolinate and, where possible, select supplements which use alternate forms of chromium such as nicotinate, chloride or other amino acid chelates.
Value:
A few years ago, the Federal Trade Commission (FTC) cracked down on several chromium companies for making unsubstantiated claims about the ability of chromium to "magically" melt away body fat without diets or exercise. The majority of claims now are couched in the "maintain and promote" terminology permitted by the Dietary Supplement Health and Education Act (DSHEA). However, because more than 90% of American diets fail to provide the recommended amount of chromium, and chromium supplements have been shown to be effective in maintaining insulin function and in helping some dieters lose body fat, chromium supplements may be an effective supplement for those individuals seeking better control of blood sugar and appetite (sweet cravings).
Dosage:
The most widely available supplements are chromium salts such as chromium polynicotinate, (ChromeMate from InterHealth Nutraceuticals), chromium picolinate (ChromeMax from Nutrition 21/AMBI) and various chromium/amino acid chelates - which help increase the absorption and availability compared to isolated chromium salts such as chromium chloride (which has an extremely low gastrointestinal absorption rate).
No Recommended Dietary Allowance (RDA) has been established for chromium, but the ESADDI (estimated safe and adequate daily dietary intake) is 50-200 mcg. Natural forms of supplemental chromium, such as chromium-rich yeast, may be absorbed somewhat more efficiently than inorganic forms of chromium, such as chloride, found in some supplements. One ounce of brewer's yeast provides approximately 100-200 mcg of chromium.
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