Dietary phosphorus, effect retention

Phosphorus Rat Lead retention Low dietary phosphorus enhances lead retention no effect on lead resorption in bone Quarterman and Morrison 1975... 

Reports of lead-nutrient interactions in experimental animals have generally described such relationships in terms of a single nutrient, using relative absorption or tissue retention in the animal to index the effect. Most of the data are concerned with the impact of dietary levels of calcium, iron, phosphorus, and vitamin D. These interaction studies are summarized in Table 2-12. 

Quarterman J, Morrison JN. 1975. The effects of dietary calcium and phosphorus on the retention and excretion of lead in rats. Br J Nutr 34 351-362. 

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. 

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...

A couple of theories have been proposed to explain how dietary Ca might possibly affect Se utilization. It has been suggested that Se availability may be directly influenced by intestinal interactions involving Ca or minerals linked to Ca utilization (e.g., phosphorus) (Lowry et al., 1985). Indirect effects on the capacity of a target tissue to respond to Se are also considered possible means by which bioavailability or retention might be influenced (Parizek, 1978). It has also been conjectured (Hill and Matrone, 1970 Howell and Hill, 1978) that elements with valence shell electronic structures most similar to Se (i.e., Se , Se, and Se " ") are most likely to act antagonistically. Based on this criterion, Ca does not fit the profile of a probable Se antagonist. 

Limited data are available about the effects of individual dietary components on absorption, and consequently the requirement, of Mn. Dietary protein and phosphorus levels (33), calcium level (34) and the effect of a partial substitution of soy protein for meat (28) have been tested in balance studies without any obvious effect of Mn absorption or retention. However, since the main route of excretion is via the bile, the conventional balance technique is probably not sensitive enough to identify dietary factors that influence Mn absorption. 

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... 

Interaction between zinc and calcium has been demonstrated In several animal studies (l- ). It has been shown that calcium antagonizes the biological effects of zinc and that calcium reduces the availability of zinc for absorption. This decrease In zinc absorption resulted In severe malnutrition and parakeratosis (1.-7.) Several studies have conclusively shown that the calclum-zlnc antagonism studied In animals Is due to excess phytic acid In the diet (, 9). However, In the absence of phytic acid, excess dietary calcium per se has also been shown to decrease the Intestinal absorption and the retention of zinc In rats (10). This Inhibitory effect on zinc absorption. Induced by calcium, was further enhanced by the addition of phosphorus to the high calcium Intake (11). 

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