The safety and efficacy of high-dose chromium - High-Dose Chromium

Alternative Medicine Review, June, 2002 by Davis W. Lamson, Steven M. Plaza

Many authors cite absorption levels of 2-3 percent of dietary chromium as organic complexes. (4,82) Chromium from brewer's yeast was absorbed in the range of 5-10 percent, (82) although others were unable to duplicate these results. (81) Chromium picolinate was found to have absorption in humans estimated at 2.8 percent [ or -] 1.14 SD. (84) Studies on rats found that 3-8 times more chromium nicotinate was absorbed and retained than was chromium picolinate or chromium chloride. After 6-12 hours, tissues retained on the average 2-4 times more chromium nicotinate than chromium picolinate. (98) Similar results in rat studies using a number of different organic complexes of chromium found the relative absorption/retention as follows: Cr nicotinate > Cr picolinate > Cr chloride). (81) Concentrations of chromium picolinate in the liver and kidney were found to be 2-6 times higher than for chromium chloride- or chromium nicotinate-fed rats, with no detectable toxicity. (45)

Drugs and Chromium Absorption

Chromium absorption is influenced by a number of drugs. Rats fed 40 mg of aspirin had an increased absorption of chromium III chloride as measured by blood levels of [sup.51]Cr. (99) Intraperitoneal injection of 5 mg indomethacin increased [sup.51]Cr levels in the blood and tissue of rats given [sup.51]Cr III chloride. (100) In contrast to aspirin and indomethacin, a number of antacids significantly decrease blood and tissue levels of [sup.51]Cr III chloride. (99,101) The decrease in absorption of [sup.51]Cr III chloride when combined with antacids (Tums[R] or Maalox[R]) has been ascribed to a competitive inhibition by the minerals in the antacids. (99)

Chromium Retention in Tissue

The extent of chromium retention in various tissues is of as much interest as the absorption of chromium compounds. Rats fed a high-chromium diet (5000 ng Cr/g food) compared to a low-chromium diet over a three-week period followed by organ dissection revealed that by far the majority of Cr concentrated in the kidneys as corn pared to liver, spleen, heart, lung, and gastrocnemius muscle. Table 2 demonstrates that not only is there a preferential organ concentration in the kidney but that the specific chromium compound had substantial effect, with chromium picolinate > nicotinate > chloride. (81)

Chromium dosage at quite high levels in animal studies showed no disturbance in liver and kidney function or tissue histology. In human studies, no abnormalities in liver or kidney function at doses as high as 1000 mcg/day of chromium picolinate were found. It remains to be determined if much higher doses will demonstrate a similar lack of toxicity. There has been no demonstration of any toxicity so far in the clinical observations of the authors with the use of chromium nicotinate at levels as high as 5000 mcg/day.

Conclusion

Deficiency of chromium can result in hypoglycemia or presentation of diabetes. Even in a healthy person, supplemental Cr can increase insulin sensitivity, and decrease fasting serum glucose and endogenous insulin production. Treatment of type 2 diabetes with Cr has led to improvement in serum glucose, insulin, and HbA1C levels. Organic chromium complexes give better results than inorganic chromium, and higher Cr doses give both faster and better improvement in glucose and lipid levels. Glucose control also improves in type 1 diabetes. Supplemental Cr reduces insulin resistance in gestational diabetes in a dose-dependent manner. Chromium is effective in reversing the diabetes caused by therapeutic use of glucocorticoids. The effects of Cr on blood glucose homeostasis are accomplished by increased activation of insulin receptors through binding of chromium with LMWCr.

Chromium can reduce elevated cholesterol and triglycerides in a dose-dependent relationship. Triglyceride reduction may take a longer time or higher dose in diabetics. One publication demonstrated increased serum DHEA levels in postmenopausal women with supplementation of low-dose chromium. Other data suggested that Cr may help in preventing osteoporosis.

Chromium appears to be the only nutritional mineral with a several hundred-fold difference between the acceptable daily intake level and the calculated reference dose. A search for any report of toxicity from supplemented Cr revealed only a few anecdotal reports of chromium picolinate toxicity. Only one of these seemed to have validity and exhibit an individual subjective reaction that resolved with cessation. Animal studies have failed to show toxicity by histological or laboratory examination at doses of Cr as high as 15 mg/kg body weight. The only trials conducted in humans showed no subjective toxicity or abnormal liver or renal function tests at 1000 mcg daily in diabetics over four months or at 500 mcg after one year. The clastogenic potential reported for Cr III picolinate in vitro was not produced by other Cr compounds, nor was it able to be reproduced in vivo in animals.