Chromium
[Advertised Claims] [Description] [ Commercial Availability and General Use] [Ergogenic Effects] [Risks and Disadvantages] [Recommendations]
Advertised
Claims
|
Chromium is a trace element and is an essential nutrient found in high concentrations in foods such as meats, whole grains, cheese, mushrooms, prunes, nuts, asparagus, beer, and wine (1). As a dietary supplement, chromium is typically sold in the form of chromium picolinate although other forms such as chromium polynicotinate are sold on the market or used in experimental research. Chromium exists as Cr3+ (trivalent chromium) in the diet and in dietary supplements (2,1). The Estimated Safe and Adequate Daily Dietary Intake (ESADDI) of chromium is 50 to 200 micrograms per day, and chromium is considered to have one of the lowest thresholds of toxicity of all nutrients (3,2). Dosages much higher than the ESADDI are widely believed to be safe for human consumption (2). However, a few studies suggest that chromium picolinate supplementation may have adverse effects in some individuals (4,5,6) (See Risks and Drawbacks).
Chromium plays an essential role in the metabolism of lipids and glucose by promoting the binding affinity between insulin and its receptors. Glucose tolerance factor (GTF) is a compound formed by the combination of chromium with nicotinic acid and various amino acids. GTF is believed to potentiate insulin activity via the formation of disulfide bridges between insulin and insulin receptors. Furthermore, chromium may play a direct role in blood lipid metabolism by stimulating lipoprotein lipase activity (1).
Insulin is the primary, anabolic hormone and plays a role in satiety and thermogenesis by regulating the hypothalamus. Many obese individuals are thought to have a reduced sensitivity to insulin which results in hyperinsulinemia which in turn results in weight gain (7,8,9). Hyperglycemia is also a result of insulin insensitivity (7). Because chromium supplementation is thought to potentiate the effect of insulin, it has been investigated as a treatment for obesity and hyperglycemia (10). However, the precise mechanisms by which chromium exerts its effects on insulin are not known.
| Commercial
Availability and General Use Chromium supplements are typically sold in the form of chromium picolinate although other forms such as chromium polynicotinate, chromium chloride, and chromium yeast are also available on the market. Chromium is often combined with other dietary supplements such as L-carnitine or pyruvate and is commonly added to other nutrition products such as protein drinks and vitamin supplements. Chromium supplements are mostly available in the form of softgel capsules and tablets. The cost of the supplements (products containing chromium without the addition of other dietary supplements) varies over a wide range. A two months supply may cost between $5 to 20 (assuming an intake of 400 micrograms per day). The dosage recommended on most product labels is between 200 micrograms to 600 micrograms daily. The Estimated Safe and Adequate Daily Dietary Intake (ESADDI) for chromium is 50-200 micrograms per day. However, chromium is generally regarded to be one of the safest of all nutrients, and there is little evidence to suggest that intakes of up to 600 micrograms per day is detrimental to human health. |
Many individuals lack the recommended amount of chromium in their diets. The U.S. Department of Agriculture (USDA) reported that the majority of Americans consume less than 50 micrograms of chromium per day (7,11). The ESADDI for chromium is 50-200 micrograms or 1-4 micromoles per day (3).
Low-calorie diets typically have low amounts of chromium. Furthermore, strenuous exercise may accelerate the loss of chromium in the urine (12,13). Consequently, athletes who are attempting to lose weight via dieting and exercise may be at a particular risk for chromium deficiencies (14). Deficiencies in dietary chromium have been linked to impairment in carbohydrate, protein, and lipid metabolism (15).
By lowering insulin concentration in the blood, chromium supplementation may reduce the amount of lipogenesis in adipose tissue. Furthermore, it has been suggested that chromium may promote gains in lean body mass (LBM) by improving the sensitivity of insulin receptors in skeletal muscle tissue and thus increasing the uptake of amino acids into the skeletal muscles (14,16). Increases in LBM are known to cause an increase in the basal metabolic rate which in turn increases the rate of fat oxidation (2).
Some studies show that dosages of 200-400 micrograms of chromium supplementation each day may enhance gains in lean body mass while concomitantly reducing body fat in exercising individuals. However, other studies do not support these findings. A summary of relevant research is presented below.
Research
Evans et al. (1989)16
Thirty-one college football players underwent 6 weeks of resistance training and received 200 micrograms of chromium picolinate daily. The subjects increased significantly in lean body mass afer the 6-week intervention.
Hasten et al. (1992)17
Fifty-nine college students (37 males, 22 females) underwent 12 weeks of resistance training and received 200 micrograms of chromium picolinate daily. The female subjects significantly increased in body weight after the 12-week intervention. The male subjects did not increase in body weight.
Hallmark et al. (1996)18
Sixteen untrained males aged 23 +/- 4 yrs. underwent 12 weeks of resistance training and received 200 micrograms of chromium picolinate daily. No significant improvement in body composition or strength was associated with chromium supplementation. (Gains in strength were not statistically different between the placebo group and the treatment group).
Clancy et al (1994)19
Thirty-six male college football players underwent 9 weeks of resistance training and received 200 micrograms of chromium picolinate daily. No changes in body composition or strength were associated with chromium supplementation.
Trent et al. (1995)7
Ninety-five navy personnel (79 men, 16 women) underwent 16 weeks of aerobic training and received 400 micrograms of chromium picolinate daily. No significant changes were observed in lean body mass, weight, or percent body fat.
Grant et al. (1997)10
Forty-three healthy, sedentary, obese females participated in a 9 week study. Treatment subjects consumed 200 micrograms of either chromium picolinate or chromium nicotinate. Subjects treated with chromium picolinate were divided into an exercise group and a non-exercise group. A fourth group exercised while consuming a placebo. Exercise training consisted of aerobic training (cycling + step aerobics) and resistance training. Subjects treated with chromium picolinate actually gained significant weight. However, there were no significant changes in lean body mass, fat mass, or percent body fat. Subjects treated with chromium nicotinate lost a significant amount of weight. However, these subjects did not decrease significantly in lean body mass, fat mass, or percent body fat.
Walker et al. (1998)14
Twenty male wrestlers (aged 18-23 years) underwent 14 weeks of resistance training, cardiovascular endurance training (long-distance runs), and anaerobic endurance/power training (middle-distance sprinting, sparring, and sparring drills). Treatment subjects consumed 200 micrograms of chromium daily during the 14-week treatment period. No significant changes were observed in lean body mass, fat mass, percent body fat, or muscular strength in the subjects treated with chromium. Maximal aerobic power increased similarly in all subjects (treatment, placebo, and control subjects) and thus was independent of chromium supplementation.
Campbell et al. (1999)20
Eighteen elderly males (aged 56-69 years) underwent 12 weeks of resistance training and received 924 micrograms of chromium picolinate daily. Gains in muscular strength, power, and lean body mass were independent of chromium supplementation.
Blood lipid metabolism
Chromium may play a direct role in blood lipid metabolism by stimulating lipoprotein lipase activity. One study reported that chromium supplementation increased blood high-density lipoprotein (HDL) concentration while lowering blood low-density lipoprotein (LDL) concentration. The mechanism by which this occurs is unknown (1,15).
| Risks and
Disadvantages Research methods and techniques used in many of the studies reporting positive effects of chromium supplementation have been questioned (1). Many studies have reported no significant benefits linked to chromium supplementation . A few reports suggest that chromium supplementation may cause certain adverse effects such as headaches, sleeplessness, and alterations in mood, cognition, motor function, perception, and various metabolic processes (4,5,6). |
| RecommendationsStudies investigating the efficacy of chromium supplementation have yielded mixed results. Furthermore, any benefits associated directly with chromium supplementation are relatively mild compared to the benefits that may be gained by exercise or diet control. Nevertheless, chromium supplementation is generally regarded to be safe within the recommended dosages (though some studies do indicate otherwise- see Risks and Drawbacks). Athletes and exercising individuals who are attempting to lose weight via dieting could theoretically benefit from chromium supplements if they are deficient in this nutrient. However, there is little evidence to support this claim. |
Article by Richard Chiang 10/19/99
2. Anderson RA. Effects of chromium on body composition and weight loss. Nutr Rev. 1998;56:266-70.
3. National Research Council. Recommended Dietary Allowances. Washington, DC: National Academy Press, 1989, pp. 241-43.
4. Schrauzer GN, Shrestha KP, Arce MF. Somatopsychological effects of chromium supplementation. J Nutr Med. 1992;3:42-8.
5. Huzonek J. Over-the-counter chromium picolinate. Am J Psychiatry. 1993;150:1560-61.
6. Lefavi RG, Anderson RA, Keith RE, Wilson GD, McMillan JL, Stone MH.
Efficacy of chromium supplementation in athletes: Emphasis on anabolism. Int J Sport
Nutr.1992;2:111-22.
7. Trent LK, Thieding-Cancel D. Effects of chromium picolinate on body composition. J Sports Med Phys Fitness. 1995;35:273-80.
8. Porte D Jr, Woods SC. Regulation of food intake and body weight of insulin. Diabetologia. 1981;20:274-80.
9. Felig P. Insulin is the mediator of feeding-related thermogenesis: insulin resistance and/or deficiency results in a thermogenic defect which contributes to the pathogenesis of obesity. Clin Physiol. 1984;4:267-73.
10. Grant KE, Chandler RM, Castle AL, Ivy JL. Chromium and exercise training: effect on
obese women. Med Sci Sports Exerc. 1997;29:992-8.
11. Anderson RA, Kozlovsky AS. Chromium intake, absorption and excretion of subjects consuming self-selected diets. Am J Clin Nutr. 1985;41:1177-83.
12. Anderson RA, Polansky MM, Bryden NA, Canary JJ. Supplemental-chromium effects on glucose, insulin, glucagon, and urinary chromium losses in subjects consuming controlled low-chromium diets. Am J Clin Nutr. 1991;54:909-16.
13. Anderson RA, Bryden NA, Polansky MM, Deuster PA. Exercise effects on chromium excretion of trained and untrained men consuming a constant diet. J Appl Physiol. 1988;64:249-52.
14. Walker LS, Bemben MG, Bemben DA, Knehans AW. Chromium picolinate effects on body composition and muscular performance in wrestlers. Med Sci Sports Exerc. 1998;30:1730-7.
15. Mertz W. Chromium in human nutrition: a review. J Nutr. 1993;123:626-33.
16. Evans GW. The effect of chromium picolinate on insulin controlled parameters in humans. Int J Bios Med Res. 11:163-180, 1989.
17. Hasten DL, Rome EP, Franks BD, Hegsted M. Effects of chromium picolinate on beginning weight training students. Int J Sport Nutr. 1992;2:343-50.
18. Hallmark MA, Reynolds TH, DeSouza CA, Dotson CO, Anderson RA, Rogers MA. Effects of chromium and resistive training on muscle strength and body composition. Med Sci Sports Exerc. 1996;28:139-44.
19. Clancy SP, Clarkson PM, DeCheke ME, Nosaka K, Freedson PS, Cunningham JJ, Valentine B. Effects of chromium picolinate supplementation on body composition, strength, and urinary chromium loss in football players. Int J Sport Nutr. 1994;4:142-53.
20. Campbell WW, Joseph LJ, Davey SL, Cyr-Campbell D, Anderson RA, Evans WJ. Effects of resistance training and chromium picolinate on body composition and skeletal muscle in older men. J Appl Physiol. 1999;86:29-39.
