Author
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MILNE, DAVID - 5450-10-00 |
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Nielsen, Forrest - Frosty |
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Submitted to: Journal of Trace Elements in Experimental Medicine
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/15/2002 Publication Date: 8/1/2003 Citation: Milne, D.B., Nielsen, F.H. 2003. High dietary fructose compared with corn starch does not heighten changes in copper absorption, retention or status indicators in men fed low dietary dietary copper. Journal of Trace Elements in Experimental Medicine. 16:27-38. Interpretive Summary: An inadequate dietary intake of copper by adult humans has been suspected to contribute to several forms of ill health including ischemic heart disease, osteoporosis, and cancer. However, confirmation that copper is of nutritional importance in the prevention of chronic disease has been elusive. Although experimental copper depletion studies have occasionally identified individuals who responded by exhibiting undesirable changes in cholesterol, blood pressure and electrocardiograms, such changes have not been consistently found. One possible reason for the inconsistency is that in copper deprivation studies other dietary factors strongly influenced the need for copper and thus had an impact on the appearance of undesirable changes with short-term copper depletion. If this is true then there may be stressors that make copper a nutritional concern and also enhance the ability to induce experimental copper deficiency signs in humans. One possible stressor of copper need is high dietary fructose, which has been shown to exacerbate signs of copper deficiency in male weanling rats. Thus, an experiment was performed on six men living on a metabolic unit. They were fed a diet with or without 20% of dietary starch being replaced by fructose while being fed 0.6 and 2.6 mg of copper per day. The men attempted to adapt to the low intake of copper by retaining absorbed copper longer. The adaptation was inadequate because copper balance became negative. Also, some mild changes in copper variables occurred. However, the response of the men to short-term copper depletion was not heightened by high dietary fructose. The findings indicate that 0.6 mg of copper per day is an inadequate intake and that high dietary fructose is not an Technical Abstract: To determine the effect of high dietary fructose on copper (Cu) metabolism and Cu status indicators in healthy men fed low dietary copper, six men aged 27 to 37 yrs completed a metabolic unit study divided into four 7-week dietary periods with a randomized, double-blind, 2 x 2 factorial design with variables of 0.6 or 2.6 mg Cu/2500 kcal and fructose or corn starch as s20% of energy. Neither type of dietary carbohydrate nor intake of Cu significantly affected absorption, but Cu deprivation resulted in negative Cu balance. The source of dietary carbohydrate did not affect the biological half-life (BHL) of Cu, but it was significantly (P<0.001) longer when dietary Cu was low (35+/-11 d mean +/- SD) than when supplemented (20 +/-5) d. The natural log of the BHL directly correlated with plasma Cu (r= 0.498, P=0.001), and immunoreactive ceruloplasmin (RID Cp) (r=0.394, P= 0.01), and was inversely related to glutathione that has a role in Cu metabolism (r=-0.510, P=0.03). Copper deprivation decreased erythrocyte superoxide dismutase activity and RID Cp when fructose was fed, but increased the activity when corn starch was fed. The RID Cp change resulted in a significant increase in the enzymatic ceruloplasmin/RID Cp radio with high dietary fructose and a decrease with corn starch substituting for fructose when dietary Cu was low. Thus, the men fed approximately 0.6 mg Cu/d for 7 weeks attempted to adapt to this low intake by retaining absorbed Cu longer. However, the adaptation was inadequate because CU balance became negative. Also, some mild changes in Cu variables associated with reactive oxygen metabolism occurred with Cu deprivation that were influenced by dietary carbohyrdrate. The response of men to short-term by high dietary fructose. |
