Fecal zinc excretion, effect

Kelsay and co-workers (27,28) observed no effects on iron balance of including 24g/day of NDF from fruits and vegetables however, negative zinc and copper balances were observed. In a second study (29), lower zinc, but not copper, balances were observed at intakes of 25g NDF/day lower intakes (10, 18g NDF) had no effect. In these studies, the effects of oxalates (from spinach) may have affected mineral balances. In a third study, a combination of consuming spinach every other day plus a daily fiber intake of 26g NDF resulted in increased fecal zinc excretion and negative balances (22) ... 

In the present study the effect of calcium and phosphorus on zinc metabolism was investigated In adult men by determining metabolic balances of zinc during different intakes of calcium and phosphorus. Three Intake levels of calcium, ranging from 200 to 2000 mg/day, and two Intake levels of phosphorus (800 and 2000 mg/day) were used during a constant dietary zinc Intake of 14.5 mg/day. Increasing the calcium Intake from 200 to 2000 mg and Increasing the phosphorus Intake from 800 to 2000 mg/day had no effect on urinary or fecal zinc excretion nor on zinc retention. absorption studies confirmed... 

Table II shows data of the effect of a high phosphorus Intake on the zinc balance. The phosphorus supplements were given to three patients during different calcium Intakes, namely, during a low calcium Intake of 200 mg per day and during higher calcium Intakes of 800 mg and 2000 mg calcium per day. The phosphorus Intake of the subjects studied was approximately 900 mg per day In the control study and was 2000 mg per day during the high phosphorus Intake. In the control study, during a low calcium Intake and a normal phosphorus Intake of 900 mg per day and a dietary zinc Intake of 17 mg per day, the urinary zinc excretion was relatively high, 1.6 mg/day, the fecal zinc excretion was In the expected range and the zinc balance was positive,...

Mean urinary zinc excretion of omnivore and vegetarian subjects were not significantly different from one another nor did the addition of ascorbic acid supplements seem to have a pronounced effect (Table IV). Fecal zinc losses were significantly hlger for the omnivore subjects than for the vegetarian... 

Several zinc absorption studies, using oral doses of ZnCl2 were carried out. 65zq plasma levels were determined serially on the day of the oral administration of the zn tracer. Urinary and fecal 65zn excretions were determined for approximately 15 days. The subjects studied were fully ambulatory males who were In good nutritional state. They were normal according to all clinical and laboratory criteria. Including the serum levels of zinc, calcium, and phosphorus. The effect of three Intake levels of calcium on the zinc balance was studied, namely, of 200, 900,... 

Metal metabolism The use of zinc in the treatment of copper deposition due to Wilson s disease was first proposed in the Netherlands by Schouwink in his 1961 PhD thesis [107, 108 ]. This was based on earher experience in veterinary medicine in Australia that zinc salts are effective in copper poisoning in sheep. Later observations showed that stimulation by zinc of metallothionein blocks the intestinal absorption of copper. Metallothionein binds both zinc and copper, but it has a higher affinity for the latter. It binds newly absorbed copper in enterocytes and prevents it from passing firom the gut into the circulation. Copper has no enterohepatic circulation, and Ihe shedding of enterocytes with copper still bound to metallothionein results in higher fecal copper excretion. 

High levels of dietary zinc were associated with marked decreases in bone calcium deposition and in the apparent retention of calcium in male weanling albino rats. Marked increases in fecal calcium levels were also observed in the zinc-fed rats. Excessive dietary zinc was associated with a shifting of phosphorus excretion from the urine to the feces. This resulted in an increase in fecal phosphorus and provided an environmental condition which would increase the possibility of the formation of insoluble calcium phosphate salts and a subsequent decrease in calcium bioavailability. The adverse effect of high dietary zinc on calcium status in young rats could be alleviated and/or reversed with calcium supplements. 

The effect of zinc toxicity on the calcium balance of young rats is presented in Table V. Marked increases in the fecal excretion of calcium was noted in the zinc-fed rats, and the overall effect of zinc toxicity was a substantial decrease in the apparent retention of calcium. The effects of zinc on calcium retention were noted as early as one week of the experimental period. 

Table VI shows the effect of 0.75% dietary zinc on the phosphorus balance in young rats. A decrease in the apparent retention of phosphorus was noted in the zinc-fed rats as early as the end of the first week. Possibly a more significant observation was the apparent movement of phosphorus excretion from the urine, the normal pathway for phosphorus excretion, to the feces in rats fed the high zinc diet. Such a shifting of the phosphorus excretion to the fecal pathway in animals fed a high zinc diet should result in an increase...

For patients who are unable to tolerate penicillamine, trientine, another chelating agent, may be used in a daily dose of 1-1.5 g. Trientine appears to have few adverse effects other than mild anemia due to iron deficiency in a few patients. Zinc acetate administered orally increases the fecal excretion of copper and is sometimes used for maintenance therapy. The dose is 50 mg three times a day. Zinc sulfate (200 mg/d orally) has also been used to decrease copper absorption. Zinc blocks copper absorption from the gastrointestinal tract by induction of intestinal cell metallothionein. Its main advantage is its low toxicity compared with that of other anticopper agents, although it may cause gastric irritation when introduced. 

Taper et al. (13) investigated the effects of zinc intake on copper utilization in adult women. The experiment involved feeding three levels of zinc, ranging from 8.0 to 24.0 mg/day. Copper retention was not affected by zinc Intake. Urine losses of zinc were from 0.4 to 0.6 mg/day and fecal excretions paralleled the intake. Percent apparent absorptions of zinc were 7.75, 9.13, and 11.50 percent when intakes were 8.0, 16.0 and 24.0 mg/day. 

Taper e al. (39) from the same laboratory as the aforementioned geriatric study, found no significant effect of dietary zinc levels when they studied 18 young women of childbearing age. Dietary copper intake was 2.0 mg day with 0.86 mg from food and 1.14 mg as supplement. Foodstuffs provided 5.63 mg of zinc, and total daily Intakes were adjusted to 8 mg (N = 7), 16 mg (N = 6) and 24 mg (N = 5). The experimental details of the supplementation with zinc and copper salts were not provided. The dietary Zn/Cu ratios were 4.0, 8.0, and 12.0 respectively the mean fecal excretion (mean SD) for the respective diets was 2.01 + 0.15, 2.10 + 0.14 and 2.02 + 0.23, respectively. Neither the fecal outputs nor the derivative apparent retention values differed significantly one from another. 

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