High Dietary Fructose Compared With Corn Starch Does Not Heighten Changes in Copper Absorption, Retention, or Status Indicators in Men Fed Low Dietary Copper

In experimental animals, high dietary fructose exacerbates signs of copper deficiency in rats. Thus, an experiment was performed to determine whether high dietary fructose affected copper metabolism and copper status indicators in healthy men who were fed low dietary copper. Six men aged 27 to 37 years 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 20% of energy. Twice during each dietary period the men consumed a standardized breakfast meal labeled with 2.5 micro Ci 67Cu, then were counted daily in a whole-body counter for 3 weeks after each meal. At the end of each dietary period, blood was collected to assess copper status. Neither type of dietary carbohydrate nor intake of copper significantly affected 67Cu absorption, but copper deprivation resulted in a negative copper balance. The source of dietary carbohydrate did not affect the biological half-life of copper, but it was significantly (P < 0.001) longer when dietary copper was low (35 ± 11 d; mean ± SD) than when supplemented (20 ± 5 days). The natural log of the biological half-life directly correlated with plasma copper (r = 0.498; P = 0.001) and immunoreactive, or radial immunodiffusion, ceruloplasmin (RID Cp; r = 0.394; P = 0.013), and was inversely related to glutathione (r = -0.510, P = 0.03). When high dietary fructose was fed, erythrocyte superoxide dismutase activity and RID Cp was lower, and the enzymatic ceruloplasmin/RID Cp ratio was higher during copper depletion than during repletion; just the opposite occurred when corn starch was fed. No other copper status indicator was affected by an interaction between dietary carbohydrate and copper or was heightened by high dietary fructose. The results indicate that men fed approximately 0.6 mg Cu/d for 7 weeks attempted to adapt to this low intake by retaining absorbed copper longer. The adaptation was inadequate because copper balance became negative. However, although copper status was decreased, the response of men to short-term dietary copper deprivation was not heightened by high dietary fructose.