Fecal calcium excretion

Diet Calcium Intake Fecal Excretion Urinary Excretion Balance... 

Table VII shows the calcium balance of zinc-fed and non-zinc-fed rats supplemented with 0.8% calcium and/or phosphorus. Marked increases in fecal calcium and corresponding decreases in apparent calcium retentions in the zinc-fed rats could be reversed with calcium supplementation. Phosphorus supplements appeared to be associated with increases in calcium retention in the absence of zinc, but decreases in calcium retention in the presence of zinc without calcium supplementation. Decreases in fecal calcium were noted in animals fed calcium supplements in the presence of phosphorus or zinc. High levels of zinc were associated with increases in fecal calcium excretion in the absence of extra calcium or in the presence of extra phosphorus. Calcium supplementation was generally associated with a decrease in the urinary excretion of calcium, while zinc and phosphorus supplements were generally associated with an increase in urinary calcium excretion.

Most of the forementioned studies which examined the influence of various dietary fiber on the bioavailability of calcium by human subjects have depended upon the comparative measurements of calcium content of diets and calcium contents of stools and urine. As reviewed by Allen (3), calcium balance studies have distinct limitations relative to accuracy and precision. However, their ease of application and cost, laboratory equipment requirements, and real (or perceived) safety in comparison to available radioactive or stable isotope methods continue to make their use popular. In calcium balance studies, calcium absorption is assumed to be the difference between calcium excretion in the feces and calcium intake. Usually this is expressed as a percent of the calcium intake. This method assumes that all fecal calcium loss is unabsorbed dietary calcium which is, of course, untrue since appreciable amounts of calcium from the body are lost via the intestinal route through the biliary tract. Hence, calcium absorption by this method may underestimate absorption of dietary calcium but is useful for comparative purposes. It has been estimated that bile salts may contribute about 100 g calcium/day to the intestinal calcium contents. Bile salt calcium has been found to be more efficiently absorbed through the intestinal mucosa than is dietary calcium (20) but less so by other investigators (21). 

Other methods used to decrease the recurrence of urolithiasis include dietary modifications that decrease calcium excretion and promote diuresis. Changing the diet from alfalfa to grass or oat hay decreases the calcium intake and should decrease the urinary excretion of calcium, since fecal calcium excretion is relatively constant in horses. Although this dietary change should decrease the total calcium excretion, it may also decrease the urinary excretion of nitrogen and the daily urine volume. The latter changes could enhance the supersaturation of urine. In theory, diuresis could be promoted further by the addition of loose salt (50-75 g per day) to the concentrate portion of the diet. However, in one study where ponies were fed sodium chloride (1, 3 or 5% of the total diet dry matter (1% is approximately 75 g sodium chloride for a 500 kg horse)), there were no differences in water intake, urine production or calcium excretion. 

A 30-85% increase in oxygen consumption was observed in mice exposed to 110 mg/kg/day in the diet for 26 days (Pugsley 1936). Fecal excretion of calcium and urinary excretion of creatine and creatinine were increased to 200%, 45%, and 400%, respectively, of preexposure levels. The toxicological significance of these changes in excretion was not clear, but high calcium excretion would be expected to result in neuromuscular toxicity and high excretion of creatine and creatinine are often a result of muscle toxicity. 

Assuming an average intake of 17.5 mmol calcium per 24 hr and net absorption of 20-40%, the fecal calcium excretion rate in healthy adults ranges from 10.5 to 14 mmol/day [27]. 

In contrast to calcium, excretion of phosphorus occurs mainly in the urine, about two-thirds of the total amount excreted being lost by this route, almost entirely as phosphates of the various cations, the remainder being excreted in feces chiefly as calcium phosphate. Fecal phosphorus is composed of unabsorbed together with re-excreted phosphate, the latter having been estimated to average 25 to 30% of the total fecal phosphorus. ... 

It has been generally established that thyroid dysfunction leads to a disturbance of mineral metabolism. In hyperthyroidism an increased excretion of calcium and phosphorus is constantly found which is diminished by iodine medication and is still further diminished after subtotal thyroidectomy. The high urinary calcium excretion also returns to normal after about 14 days treatment with the antithyroid drug thiouracil. A high fecal excretion of calcium has also been reported but is not a clearly established feature of hyperthyroidism. Long-standing untreated hyperthyroidism is accompanied by an osteoporosis, the cause of which is still a matter of differing opinion. 

Apparent absorption (intake minus fecal excretion) of calcium decreased when the diet contained muffins with added sodium phytate to increase the molar ratio of phytate/calcium from 0.04 to 0.14 and 0.24. One-half of the men excreted more calcium in feces than was consumed when the high phytate diet was consumed. People consuming diets with molar ratios of phytate/calcium exceeding 0.2 may be at risk of calcium deficiency because of low bioavailability of dietary calcium unless physiological adjustments can be accomplished that maintain homeostasis. 

Bricker et al. (30) reported that there were no statistically significant differences between the calcium balances of eight women on cocoa and non-cocoa diets. The women were studied for three to seven 4-day periods. Calcium intake was 670 mg/day with the addition of milk and 679 and 755 mg/day with the addition of milk and cocoa. Five levels of cocoa, supplying from 5.6-52.6 g/day, were tested. These amounts would likely contain from 25-280 mg of oxalic acid, which was not nearly as much as was added when spinach was fed. With the inclusion of cocoa in the diet, the urinary calcium fell and fecal calcium rose. There were also increases in the fecal excretion of dry matter and nitrogen. 

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. 

Fat and calcium from infant formulas high in stearate and palmitate have been found to be poorly utilized (70). Fecal excretion of palmitate and stearate and of calcium were correlated by Hanna et al. (64). 

Jacobsen, R., Lorenzen, J. K., Toubro, S., Krog-Mikkelsen, I., and Astrup, A. (2005). Effect of short-term high dietary calcium intake on 24-h energy expenditure, fat oxidation, and fecal fat excretion. Int. J. Obes. (Lond.) 29, 292-301. 

Comparative effects of calcium lactate and milk on apparent manganese utilization by humans are shown on Table II (7). In this study, 10 adult human subjects were fed 900 mg calcium from milk or 916 mg of calcium from calcium lactate/subject/day. Calcium provided by the basal diet was maintained constant. The increase in fecal manganese excretion with the calcium lactate supplemented diet in comparison to values when milk was the supplemental manganese source suggests that calcium supplied by milk had a lesser adverse effect on manganese absorption than did that from calcium lactate (Table II). 

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... 

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,... 

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,...

The results obtained In zinc balance studies during different Intake levels of calcium and phosphorus were In agreement In Zn absorption studies. Figure 1 shows data of f> Zn plasma levels and of the fecal excretions following a single oral... 

Total calcium turnover Is five to ten times greater in the newborn than in the adult This is reflected in the fact that normalized calcium intake is 5-10 times higher in the newborn than in the adult although the fraction absorbed (Va/Vi) is similar A second observation is that in all five newborns more calcium is lost through the endogenous fecal route than by urinary excretion The reverse is true for typical adults Finally, the is in positive balance for both bone and total organism calcium in contrast to the typical adult ... 

Ingestion Absorption Urinary excretion Endogenous fecal excretion Bone Accretion Bone resorption Total fecal excretion Total calcium balance... 

With the typical dietary intake of calcium (800 mg/day), about 20% of the calcium is absorbed. Fecal Ca is about 640 mg/day and urinary Ca is about 160 mg/day. Urinary calcium increases somewhat with an increase in intake. For any given increase, urinary Ca increases by an amount equivalent to about 6,0% of the increase in intake. Fecal Ca consists of the unabsorbed mineral and a small amount of Ca secreted into the gastrointestinal tract (100-150 mg/day). An amount of Ca equivalent to 1 to 6% of the total fecal Ca is excreted in the bile I eGrazia and Rich, 1964). Urinary Ca generally ranges from 100 to 250 mg/day. The Ca lost via the skin is about 15 mg/day, with increased losses occurring in the sweat during work in warm climates. 

Studies with baby pigs revealed that urinary Ca levels vt crc low and equivalent to about 2% of the intake, Fecal Ca was equivalent to about 21% of the intake. The remaining calcium was retained and used for growth. The excreted phosphate was more equally distributed in the urine and feces, w here the urinary phosphate was equivalent to 12 to i7% of the intake and the fecal phosphate to about 13% of the intake. The remaining phosphate was used for growth (Miller ef al, 1964). 

Phosphate is better used when supplied by food than when supplied by phosphate salts, such as potassium phosphate. The food phosphate occurs largely as phosphate esters and, with gradual hydrolysis, enters the body relatively slowly and is used efficiently in the metabolic processes. Phosphate supplied as inorganic phosphate is rapidly absorbed, with a tendency to be excreted in the urine rather than to be used by tissues (Schuette and Linkswilcr, 1962). The phosphate in bran occurs largely in the form of phytic acid (inositol hexaphosphate). The phosphate groups of fhis compound may be only partially hydrolyzed in the gut- Phytic acid tends to be excreted via the fecal route as a complex with iron or calcium. 

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