Chromium

Chromium is a mineral that is essential to human health. In its trivalent form (meaning that it can bond with three other atoms)—the only form found in food and supplements—chromium appears to be among the safest of nutrients. The hexavalent form—hexa means six—is toxic, but it is not a nutrient and is not encountered in food.

Chromium plays a role in the body’s use of energy-providing carbohydrates, protein and fat and, when in short supply, is associated with impaired glucose tolerance and diabetes-like symptoms.[1] In 1977, the first published case of a chromium-diabetes link showed that the severe diabetic symptoms that developed in a woman while on long-term parenteral nutrition (intravenous feeding) were alleviated by supplemental chromium.[2]

Not only can insufficient chromium intake result in diabetic symptoms (e.g., increased thirst, increased hunger, frequent trips to the bathroom, blurred vision, feeling tired most of the time, slow healing of sores, frequent infections), but elevated insulin and blood glucose concentrations (conditions suggestive of diabetes) can lead to increased urinary excretion of chromium,[3] creating a vicious circle.

Chromium occurs widely in the food supply—in meats, poultry, fish, grains, and other plant foods. A serving of meat, poultry, or fish typically provides 1 to 2 micrograms (mcg) of chromium. Concentrations of chromium in plant foods are widely variable, depending on the amount of chromium in the soil. (Chromium is not essential for plants to grow.) High-bran cereals are usually, but not always, high in chromium. Dairy products are generally low in chromium.

Supplemental forms of chromium include chromium picolinate, chromium polynicotinate, and chromium chloride. Absorption of chromium picolinate, though limited (less than 4 percent), is still significantly greater than that of the other forms.[4], [5] The low percentage absorption, which decreases further when intake is increased, may be part of the reason chromium is not toxic. Absorption of chromium appears to be greatly increased by the concurrent presence of ascorbic acid.[6]

Uses

Elevated Fasting Glucose and Insulin Resistance

Chromium deficiency causes insulin resistance, and supplementation with adequate chromium overcomes that resistance. (There are, however, other causes of insulin resistance that will not be overcome by chromium supplementation.) In a four-month, double-blind study carried out in China, 180 people with type 2 diabetes were given twice-daily doses of either placebo, 100 mcg chromium (as picolinate) or 500 mcg chromium (as picolinate). The group taking 1000 mcg/day showed significant reductions in fasting glucose and fasting insulin, blood glucose and insulin concentrations two hours after a glucose load, and glycosylated hemoglobin (HbA1C—a marker of long-term glucose control; lower is better). At 200 mcg/day, there was no improvement in fasting or two-hour glucose but two-hour insulin decreased as much as with 1000 mcg/day.[7] Other studies have shown significant improvements in regulation of carbohydrate metabolism blood lipid parameters in subjects with type 2 diabetes by supplementing with a combination of chromium (600 mcg of chromium as chromium picolinate/day) and biotin (2 mg/day).[8],[9]

Weight Loss

Disappointingly, most controlled studies have not supported claims that chromium aids weight loss or change in body composition.[10],[11] One study, however, reported that 600 mcg of niacin-bound chromium (i.e., chromium polynicotinate) daily in combination with a modest dietary and exercise regimen for two months in overweight women resulted in more fat loss and less loss of lean body mass than in women who undertook the dietary and exercise regimen without the chromium supplement. Total weight loss was not different for the two groups.[12]

Bodybuilding

Claims that chromium supplementation can enhance muscle building during weight training have not been borne out by research. Analysis of 12 studies showed that chromium supplementation in combination with weight training yielded a small, nonsignificant increase of 0.08% in net lean mass gain over that achieved with placebo.[13]

How Much to Take

The Adequate Intake (AI) as published by the Food and Nutrition Board and the Institute of Medicine is 35 mcg/day for young men and 25 mcg/day for young women.[14] However, according to the same publication, there are factors that affect the chromium requirement. High intake of simple sugars causes increased urinary excretion of chromium and thereby increases the chromium requirement, as does a high intake of phytic acid (common in grains), which interferes with intestinal absorption of chromium. Also, in animal models, non-steroidal anti-inflammatory drugs have resulted in increased urinary excretion of chromium and antacids reduced absorption.

A serving size commonly recommended by manufacturers is 200 micrograms/day. As seen in the China study mentioned above, however, 1000 micrograms was more effective than 200 micrograms for blood glucose regulation.

Cautions

No adverse effects have been convincingly associated with excess intakes of chromium from food or supplements.[14]


References

[1] Glinsmann WH & Mertz W. Effect of trivalent chromium on glucose tolerance. Metabolism 1966; 15:510-519.

[2] Jeejeebhoy KN et al. Chromium deficiency, glucose intolerance, and neuropathy reversed by chromium supplementation in a patient receiving long-term total parenteral nutrition. Am J Clin Nutr 1977; 30:531-538.

[3] Vincent JB. Recent advances in the nutritional biochemistry of trivalent chromium. Proc Nutr Soc 2004; 63(1):41-47.

[4] Anderson RA et al. Dietary chromium effects on tissue chromium concentration and chromium absorption in rats. J Trace Elem Exp Med 1996; 9:11-25.

[5] DiSilvestra RA & Dy E. Comparison of acute absorption of commercially available chromium supplements. J Trace Elem Med Biol 2007; 21(2):120-124.

[6] Offenbacher 1994

[7] Anderson RA et al. Elevated intakes of supplemental chromium improve glucose and insulin variables with type 2 diabetes. Diabetes 1997; 46:1786-1791.

[8] Albarracin CA et al. Chromium picolinate and biotin combination improves glucose metabolism in treated, uncontrolled overweight to obese patients with type 2 diabetes. Diabetes Metab Res Rev 2008; 24(1):41-51.

[9] Albarracin C et al. Combination of chromium and biotin improves coronary risk factors in hypercholesterolemic type 2 diabetes mellitus: a placebo-controlled, double-blind randomized clinical trial. J Cardiometab Syndr 2007; 2(2):91-97.

[10] Volpe SL et al. Effect of chromium supplementation and exercise on body composition, resting metabolic rate and selected biochemical parameters in moderately obese women following an exercise program. J Am Coll Nutr 2001; 20(4):293-306.

[11] Lukaski HC et al. Chromium picolinate supplementation in women: effects on body weight, composition, and iron status. Nutrition 2007; 23(3):187-195.

[12] Crawford V et al. Effects of niacin-bound chromium supplementation on body composition in overweight African-American women. Diabetes Obes Metab 1999; 1(6):331-337.

[13] Nissen SL & Sharp RL. Effect of dietary supplements on lean mass and strength gains with resistance exercise: a meta-analysis. J Appl Physiol 2003; 94(2):651-659.

[14] Dietary Reference Intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. (2000) National Academies Press, Washington, D.C.