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Effects of copper, iron, and ascorbic acid on manganese availability to rats
1USDA, ARS, Grand Forks Human Nutrition Research Center, North Dakota 58202-7166.
Abstract:
Four experiments were done to characterize the interactions of copper, iron, and ascorbic acid with manganese in rats. All experiments were factorially arranged Dietary Mn concentrations were less than 1 micrograms/g (Mn0) and 50 micrograms/g (Mn+). Dietary Cu was less than 1 mg/g (Cu0) and 5 micrograms/g (Cu+); dietary Fe was 10 micrograms/g (Fe10) and 140 micrograms/g (Fe140). Ascorbic acid (Asc) was not added to the diet or added at a concentration of 10 g/kg diet. Experiment 1 had two variables, Mn and Cu; in Experiment 2, the variables were Mn and Asc. In Experiment 3, the variables were Mn, Cu, and Asc; in Experiment 4, they were Mn, Cu, and Fe. Definite interactions between Mn and Cu were observed, but they tended to be less pronounced than interactions between Mn and Fe. Cu depressed absorption of 54Mn and accelerated its turnover. In addition, adequate Cu (Cu+), compared with Cu0, depressed liver, plasma, and whole blood Mn of rats. Absorption of 67Cu was higher in animals fed Mn0 diets than in those fed Mn+. Ascorbic acid depressed Mn superoxide dismutase activity and increased Cu superoxide dismutase activity in the heart. The addition of ascorbic acid to the diet did not affect Mn concentration in the liver or blood. Absorption of 54Mn was depressed in rats fed Fe140 compared with those fed Fe10. Interactions among Fe, Cu, and Mn resulted in a tendency for Mn superoxide dismutase activity to be lower in rats fed Fe140 than in rats fed Fe10. Within the physiologic range of dietary concentrations, Mn and Cu have opposite effects on many factors that tend to balance one another. The effects of ascorbic acid on Mn metabolism are much less pronounced than effects of dietary Cu, which in turn affects Mn metabolism less than does Fe.
Insights
Interactions between manganese (Mn), copper (Cu), and iron (Fe) were studied in rats. Iron significantly impacted Mn metabolism, while copper had moderate effects, and ascorbic acid showed minimal influence.
Area of Science:
- Nutritional Biochemistry
- Mineral Metabolism
- Toxicology
Background:
- Manganese (Mn) is an essential trace element involved in various physiological processes.
- Interactions between dietary minerals like copper (Cu), iron (Fe), and nutrients such as ascorbic acid (Asc) can significantly influence Mn bioavailability and metabolism.
- Understanding these interactions is crucial for optimizing nutritional strategies and preventing mineral toxicities or deficiencies.
Purpose of the Study:
- To investigate the complex interactions of dietary manganese (Mn) with copper (Cu), iron (Fe), and ascorbic acid (Asc) in rats.
- To quantify the effects of varying dietary levels of these elements on Mn absorption, turnover, and tissue distribution.
- To elucidate the impact of these interactions on specific enzyme activities, such as Mn and Cu superoxide dismutase.
Main Methods:
- Four factorial experiments were conducted using rats with controlled dietary concentrations of Mn, Cu, Fe, and Asc.
- Radioisotopes (54Mn and 67Cu) were used to trace mineral absorption and turnover.
- Tissue (liver, plasma, whole blood) and enzyme (superoxide dismutase) analyses were performed to assess mineral status and activity.
Main Results:
- Copper (Cu) significantly depressed 54Mn absorption and accelerated its turnover, also reducing Mn levels in liver, plasma, and blood.
- Iron (Fe) markedly influenced Mn metabolism, with high Fe intake (Fe140) reducing 54Mn absorption compared to lower intake (Fe10).
- Ascorbic acid (Asc) had minimal effects on Mn concentrations but altered superoxide dismutase activities, increasing Cu-SOD and decreasing Mn-SOD.
Conclusions:
- Dietary iron (Fe) exerts a more pronounced effect on manganese (Mn) metabolism than copper (Cu) or ascorbic acid (Asc).
- Copper (Cu) and iron (Fe) exhibit antagonistic effects on Mn absorption and utilization, with implications for nutritional management.
- Ascorbic acid's impact on Mn metabolism is less significant compared to that of essential minerals like Cu and Fe.