Author
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Anderson, Richard |
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 3/18/2003 Publication Date: 4/2/2003 Citation: Anderson, R.A. 2003. Absorption of dietary chromium [abstract]. Paper No. 25. Interpretive Summary: Technical Abstract: Dietary chromium absorption is in the region of 0.4 to 3% and is inversely related to total dietary Cr intake at daily intakes of less than 40 ug. Above 40 ug, absorption remains constant and there is no evidence of a saturation of total Cr absorbed. Ascorbic acid and oxalate increase Cr absorption with minimal effects of phytate. Protaglandins decrease Cr absorption and aspirin and indomethacin, which inhibit prostaglandins, increase Cr absorption. Once absorbed, Cr is transported via transferrin, the same protein that is involved in iron transport. In the rat, a Cr-nicotinic acid-glycine-cysteine-glutamic acid complex was shown to be absorbed better than the other forms of Cr tested but this complex was shown to be ineffective in humans. Follow-up human studies demonstrated that not only the form of Cr is important but also other components involved in formulating the capsules. Carbohydrates, used as fillers in capsules, were shown to bind to several forms of Cr making them essentially inert regarding absorption. Stable Cr complexes involving histidine were shown to have the best absorption by humans followed by Crpicolinate. Stresses including high sugar intake, acute exercise, pregnancy, lactation and physical trauma have all been shown to increase urinary Cr losses and may also have negative effects on Cr absorption. While acute exercise is a stress, exercise training leads to not only improved glucose and insulin metabolism but also increased Cr absorption based upon the increased absorption of a stable isotope of Cr which can be used to differentiate the effects on absorption from those on excretion. |
