Chromium supplements
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Chromium Supplements: Chromium is not all it's beefed up to be.
Chromium (Cr) supplements are enthusiastically marketed to strength athletes and body builders. The hype claims that this mineral is a safe and effective alternative to steroids and growth hormone, as it can increase muscle mass and decrease body fat. It's true that chromium is involved in helping insulin to achieve its work in the body. The theory goes that taking chromium supplements encourages the uptake of extra amino acids into muscle cells by zapping up the activity of insulin.
Preliminary studies in the late 1980s suggested that increases in lean body mass and decreases in body fat occurred with Cr supplementation, when the supplements were taken alongside a resistance training programme. Despite the delightful results reported (eg, a 2.6 kg increase in lean tissue over six weeks), the research has been criticised - for example, participants were not screened for steroid use, and the methods used to measure body composition are not very reliable and can vary according to who is doing the measuring.
Researchers from the University of Maryland and the Beltsville Human Nutrition Centre recently collaborated on a far more rigorous assessment of chromium supplementation ('Effects of chromium and resistive training on muscle strength and body composition', Hallmark et al, Med & Sci in Sport & Ex, vol 28, pp 139-144).
Sixteen healthy, untrained males were recruited (mean age 24 years). First they were given a standardised strength test to gauge their upper and lower body strength using exercises that included leg press, leg extension, chest press and overhead press. They were then sorted into pairs, matched for their initial strength levels. One member of each pair was allocated to take a Cr supplement (200ug of Cr as Chromium picolinate), the other member a placebo. The allocation was performed at random, and the volunteers were unaware which tablet they were getting. Dietary records were also completed by the volunteers for three consecutive weekdays to give a rough estimate of the Cr content of their diet and to ensure they were getting enough protein.
The volunteers then trained three times a week for 12 weeks. The training programme included a warm-up and stretching component, followed by two sets of 8-10 repetitions of nine standardised exercises using resistance exercise machines and free weights. Training logs were reviewed weekly and subjects instructed to increase the resistance when more than 10 reps could be completed.
Body composition was assessed before and after 12 weeks of resistive training using hydrodensitometry - that's science-speak for underwater weighing, traditionally reckoned to be the most accurate method available for determining body composition. Once an allowance has been made for air in the lungs, a figure for overall body density can be reached. This is then translated into percentages of fat and lean tissue using standardised equations. After the 12 week training period, the same standardised strength test used before the training was readministered.
The results revealed that, after the resistive training, there were significant increases in upper, lower and total body muscle strength in both groups. However, there was no significant difference between the group taking the chromium supplement and the group only taking placebo. Similarly, there was no significant difference in body weight, percentage body fat or lean body mass in either group. The only thing that distinguished the Cr supplementers was that they excreted more chromium in their urine. This is consistent with other research which has found increased chromium excretion rates once intake rises above 40ug. So, sadly, it seems to be a case of money flushed down the bowl for anyone buying chromium tablets in the hope of beefing themselves up.
Researchers from the University of Maryland and the Beltsville Human Nutrition Centre recently collaborated on a far more rigorous assessment of chromium supplementation ('Effects of chromium and resistive training on muscle strength and body composition', Hallmark et al, Med & Sci in Sport & Ex, vol 28, pp 139-144).
Sixteen healthy, untrained males were recruited (mean age 24 years). First they were given a standardised strength test to gauge their upper and lower body strength using exercises that included leg press, leg extension, chest press and overhead press. They were then sorted into pairs, matched for their initial strength levels. One member of each pair was allocated to take a Cr supplement (200ug of Cr as Chromium picolinate), the other member a placebo. The allocation was performed at random, and the volunteers were unaware which tablet they were getting. Dietary records were also completed by the volunteers for three consecutive weekdays to give a rough estimate of the Cr content of their diet and to ensure they were getting enough protein.
The volunteers then trained three times a week for 12 weeks. The training programme included a warm-up and stretching component, followed by two sets of 8-10 repetitions of nine standardised exercises using resistance exercise machines and free weights. Training logs were reviewed weekly and subjects instructed to increase the resistance when more than 10 reps could be completed.
Body composition was assessed before and after 12 weeks of resistive training using hydrodensitometry - that's science-speak for underwater weighing, traditionally reckoned to be the most accurate method available for determining body composition. Once an allowance has been made for air in the lungs, a figure for overall body density can be reached. This is then translated into percentages of fat and lean tissue using standardised equations. After the 12 week training period, the same standardised strength test used before the training was readministered.
The results revealed that, after the resistive training, there were significant increases in upper, lower and total body muscle strength in both groups. However, there was no significant difference between the group taking the chromium supplement and the group only taking placebo. Similarly, there was no significant difference in body weight, percentage body fat or lean body mass in either group. The only thing that distinguished the Cr supplementers was that they excreted more chromium in their urine. This is consistent with other research which has found increased chromium excretion rates once intake rises above 40ug. So, sadly, it seems to be a case of money flushed down the bowl for anyone buying chromium tablets in the hope of beefing themselves up.
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