Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 29, 1996
Publication Date: N/A
Interpretive Summary: Advertisements advancing the use of chromium supplements to promote weight loss, fat loss and gain of muscle can be found in many magazines and newspapers throughout the United States. However, the scientific basis for these claims is generally lacking. We conducted a study in which young men consumed capsules containing chromium in different chemical forms or a placebo that did not contain chromium and participated in a controlled program of exercise to gain muscular strength for eight weeks. We found that consumption of chromium supplements did not improve muscle gain, fat loss or strength gain as compared to other men who did not receive supplemental chromium. These findings indicate no increased benefit of chromium supplementation on changes in body composition during weight training. We suggest that use of chromium supplements may have a beneficial effect only in individuals who have reduced amounts of chromium in their bodies. Thus, chromium supplementation is indicated only for individuals who have depleted body chromium stores. At this time, however, methods for the assessment of human chromium status are not sufficiently sensitive to identify individuals who might benefit from chromium supplementation. This information will be useful to dietitians and nutritionists who seek to identify the biological role of chromium in humans and to individuals who want valid information about the benefits of chromium supplementation.
Technical Abstract: The effects of 8 wk of daily chromium (Cr) supplementation (170-180 ug as Cr chloride or Cr picolinate) or placebo (5 ug Cr) and weight training were examined in 36 men in a double-blind design. Strength, mesomorphy, fat-free mass, and muscle mass increased (p<0.0001) with resistance training independently of Cr supplementation. Protein, magnesium (Mg), zinc (Zn), copper, and iron intakes equalled or exceeded the RDA or ESADDI during training and did not change (p>0.05) from pre-training intakes. Cr supplementation increased (p<0.05) serum Cr concentration and urinary Cr excretion without a difference based on chemical form of Cr. Resistance training was associated with a decrease (p<0.05) in serum ferritin, total iron binding capacity, transferrin saturation, ratio of enzymatic to immunoreactive ceruloplasmin, and plasma Cu independently of Cr supplementation. As compared to pre-training values, urinary Mg excretion increased (p<0.05) and urinary Zn output tended to decrease during the first 4 wk of resistance training then returned to baseline values for the final 4 wk, which suggests an adaptation in mineral excretion in response to weight training. These findings suggest that routine Cr supplementation has no beneficial effects on body composition change or strength gain in men. Whether Cr supplementation of individuals with diminished Cr nutriture facilitates propitious changes in body structure and function, remains to be determined.