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Adaptive responses in men fed low- and high-copper diets
Linda J Harvey1, Gosia Majsak-Newman, Jack R Dainty
1Nutrition and Consumer Science Division, Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK.
The British Journal of Nutrition
|July 8, 2003
Summary
Copper (Cu) homeostasis in adult men is maintained by adjusting endogenous losses, not absorption, across varying dietary intakes. This study used stable isotopes to track Cu metabolism, revealing significant reductions in Cu excretion on lower-intake diets.
Area of Science:
- Human Nutrition
- Trace Element Metabolism
- Biochemical Homeostasis
Background:
- Copper (Cu) metabolism research is limited by a lack of sensitive biomarkers and suitable isotopic labels.
- Existing data suggest Cu homeostasis relies on absorption and endogenous loss modifications.
- Understanding these regulatory mechanisms is crucial for nutritional science.
Purpose of the Study:
- To quantify copper absorption and endogenous losses in adult men using stable-isotope techniques.
- To investigate the impact of varying dietary copper intakes on copper homeostasis.
- To elucidate the primary mechanisms maintaining copper balance.
Main Methods:
- Employed stable-isotope techniques with highly enriched 65Cu.
- Measured copper absorption (apparent and true) and endogenous excretion.
- Utilized controlled diets with low (0.7 mg/d), moderate (1.6 mg/d), and high (6.0 mg/d) copper levels over 8-week periods with washout phases.
Main Results:
- Apparent and true copper absorption rates did not significantly differ between low- and high-copper diets (41-48%).
- Endogenous copper losses were significantly reduced on low- (0.45 mg/d) and medium- (0.81 mg/d) copper diets compared to the high-copper diet (2.46 mg/d).
- No significant biochemical changes were observed due to dietary copper variations.
Conclusions:
- Copper homeostasis is maintained across a wide range of intakes in adult men.
- The primary mechanism for maintaining copper balance, especially at lower intakes, involves significant adjustments in endogenous copper excretion.
- The body adapts more rapidly to lower copper intakes primarily through reduced excretion.