Calcium retention

Effect of a new canning process on cell wall pectic substances, calcium retention and texture of canned carrots... 

Bueline T, Cosma M and Appenzeller M. 2001. Diet acids and alkali influence calcium retention in bone. Osteoporosis Int 12 193 199. 

Calcium retention is dependent on two factors, absorption and excretion. Normal subjects have been observed to have apparent calcium absorptions of 23 (sd = 12) to 27 (sd = 17) percent of the calcium from normal diets (21,22). For 20 women aged 55 to 65 consuming 629 (se = 92) milligrams dietary calcium daily, the apparent absorption was 32.1 (se = 1.9) percent (23). An apparent calcium absorption of 29.5 percent (n = 130) may be calculated from data published by Heaney et al. (15). Apparent absorption values from 29 to 42 percent may be calculated from data published by Linkswiler (24,25). However, much lower apparent absorption values of 6 to 15 percent may also be calculated from data published from the same laboratory (26). Although there is considerable variability in the apparent absorption values determined from many studies, a conservative value of 25 percent seems realistic for normal people consuming typical diets. 

Dietary phosphorus also affects calcium metabolism. Polyphosphate decreases calcium absorption in young men while orthophosphate supplement does not (26J. However, in the rat all forms of phosphate decrease calcium absorption about equally (31). However, widely divergent dietary calcium phosphorus ratios do not seem to affect calcium utilization by people as long as there is adequate phosphorus intake (32). In general phosphorus stimulates calcium retention in man (3277... 

Many other dietary factors have been reported to affect calcium bioavailability. Phytate, fiber, cellulose, uronic acids, sodium alginate, oxalate, fat (only in the presence of steatorrhea), and alcohol have been reported to decrease calcium bioavailability (15). Lactose and medium chain triglyceride increase it (15). FTuoride also affects calcium retention primarily by stimulating bone formation thereby decreasing calcium excretion (33-38). The effects of fluoride on calcium utilization have been variable (34,38,39). 

Bottom, J.S. "The Effect of High Protein, Low Pyridoxine Diet on Calcium Retention in Rats", M.S. Thesis, Utah State University, Logan, Utah, 1978. 

In attempting to reconcile these findings, it should be pointed out that rats may not be appropriate models for the study of calcium metabolism in humans. Unlike humans, the rat does not undergo epiphyseal plate closure and does not have a significant haversian remodeling sequence (21) Furthermore, rats excrete only l-270 of their calcium intake in their urine whereas humans excrete approximately 20-30% or more. This fact is especially significant, since most of the known effects of phosphates on calcium retention in humans are effected by alterations in urinary calcium. 

Age, calcium intake, hormonal status, exercise and vitamin status have all been implicated in the development of osteoporosis. Estrogen levels represent an important factor in skeletal calcium retention and homeostasis. In therapeutic trials in which post-menopausal women were given daily doses of estrogens, such therapy has been demonstrated to be partially effective in reducing the rate of bone resorption. However, this therapy has the concomitant hazard of endometrial cancer (10). Vitamin D and its hormones have been given considerable attention in the more recent studies. Without adequate dietary and tissue levels of such vitamins, calcium absorption and bone status will be impaired. 

Bloom (12J reported that in both older rats (63 days of age) and younger rats (33 days of age) the amount of calcium retained was less when 5% dried spinach, either raw or cooked, was included in the diet in 1-week balance studies (Figure 1). The experimental diets contained about 0.4% calcium, and one drop of cod liver oil was given each rat every day. Most of the calcium excretion on the spinach diet was in the feces. Retentions of calcium on the basal low fiber diet and on diets containing filter paper in amounts to equal the crude fiber in spinach or 12 times the crude fiber in spinach were high. There was no significant difference in calcium retentions between raw and cooked spinach. The low retention of calcium from spinach could not be attributed to the presence of crude fiber in the diet. 

Tisdall et al. (14) obtained poor weight gains and low calcium retention in rats fed 10% dried, cooked spinach with a low calcium (0.041 g percent) diet. Rats 28 days of age were placed on a low calcium diet, or the low calcium diet containing 10% dried spinach, 5.83% dried tomatoes, or 1.88% dried spinach for 4 weeks each. 

Calcium contents of whole rats were determined at the end of the experiment. Weight gains and calcium retentions were better when the animals were fed tomatoes than when they were fed spinach, even though the calcium intake on the higher level of spinach was about 20 times greater than when tomatoes were fed. 

Spiers (18) reported that the feeding of 14% dried New England spinach in the diet resulted in decreased growth and less calcium retention, as determined by body calcium content (Figure 3). Rats 28 days old were fed until 60 days of age. All diets contained about 0.3% calcium, and in the control diet practically all of the calcium was from skim milk. In the other diets, one-half of the skim milk was replaced by turnip greens, tendergreens, collards, kale, or New Zealand spinach to furnish an equal amount of calcium. Spinach was the only one of the greens fed which contained considerable oxalic acid. The calcium of the spinach appeared not only to be utilized poorly, but spinach also impaired utilization of the milk calcium. Food intake of the rats on the spinach diet was also lower. 

Lovelace et al. (20) noted that the effect of oxalic acid on calcium retention depended on the age of the animal (Figure 4). The two experimental diets contained cod liver oil and 0.3% calcium. Milk was the main source of calcium, and to one diet was added 60 mg of potassium oxalate daily. Ten-day balances were determined throughout the study until rats were 175 days of age. At 50 days of age, rats fed oxalate retained about 25% of the calcium,... 

At 428 days the experimental diets were resumed for two 14-day periods. When the rats were 450 days of age, their calcium retention was about 6% when no oxalate was added, and those given oxalate were in negative balance. 

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 V. Effect of Zinc Toxicity on Calcium Retention in Young Rats...

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.

Extrapolation of desirable calcium retention from 4 to 8 years... 

Desirable calcium retention = the intake at which there is no net loss of calcium. 

Braun, M., Martin, B. R., Kern, M., McCabe, G. P., Peacock, M., Jiang, Z., and Weaver, C. M. (2006). Calcium retention in adolescent boys on a range of controlled calcium intakes. 

Shipp, C. C., Maletskos, C. J., and Dawson-Hughes, B. (1987). Measurement of 47 calcium retention with a whole-body cotmter. Calcif. Tissue Int. 41, 307-312. 

Mitra and Prakash, 1957). If we look at data concerning the pair K-Ca, it is apparent that Ca is favored in the montmorillonite at 25°C and this segregation is accentuated as temperature rises above 50°C. Increases of total ionic concentration in the fluid also favors calcium retention. During burial where temperatures are higher and fluids more saline, one would expect to produce calcic montmorillonites which would be stable well above 100°C if their stability is that of calcic beidellite. Again, the deductions based upon laboratory experiments do not appear to agree with observations on natural minerals. 

Blair, R., English, P.R. and Michie, W. (1965) Effect of calcium source on calcium retention in the young chick. British Poultry Science 6,355-356. 

In the normal infant a wide range of calcium retention has been reported by Hoobler (H8), Telfer (Tl), Daniels and Stearns (D2), Flood (F5), Stearns (S10), Jeans et al. (Jla), and Harrison (H4). From these authors we have obtained the results of 24 calcium balances in healthy infants (7-12 months), fed on cow s milk or on evaporated milk, with, so far as can be ascertained, a normal intake of vitamin D. On an average intake of 1.17 g calcium daily, the mean retention of calcium was 32 % (range 0-79 %) or 0.38 g. This agrees very closely with the daily retention of calcium in a similar age group reported by Sherman and Hawley (S3) from their study of German published reports and with the calculated requirements of the body at this age (LI). 

Forfar et al. (F7) have reported the calcium balance in 3 active cases of idiopathic hypercalcemia. The mean calcium intake was 1.02g/day and the mean retention was 49% or 0.45g/day. Morgan et al. (M3) observed retentions of 53 % and 54 % in two cases, the actual daily retentions being 0.46g/day and (on a low calcium intake) 0.31 g/day. These results suggest that there may be some increased calcium retention in idiopathic hypercalcemia. As there is at the same time hypercalcuria without evidence of loss of calcium from bones, the most likely explanation is that there is increased alimentary absorption of calcium. 

A low-calcium diet lowers the serum calcium level in idiopathic hypercalcemia of infancy (B5, F4, F7, Ml, R4, S8). It results in a marked reduction in calcium retention and can convert a strongly positive calcium balance to a less positive or even negative one (F7, Ml). 

In an active case cortisone also antagonized the effect of calciferol in that when the latter was administered in a dosage of 100,000 units daily by mouth along with 25 mg of cortisone, the expected increase in calcium retention did not occur. Indeed the calcium retention was lower than that found on a similar diet without any added cortisone or calciferol. The retentions were 48 % without treatment, 73 % on calciferol alone, and 25 % on calciferol plus cortisone (F7). 

Morgan et al. (M3) examined the effect of the administration of EDTA in idiopathic hypercalcemia. Given orally, a dosage of up to 3 g daily resulted in a fall in the serum calcium level. Given subcutaneously in a dosage of 1 g daily, there was a fall in calcium retention in a balance study, a retention of 51 % being converted to a retention of 28 % on similar dietary intakes of calcium. There was an increase in the urinary excretion of calcium. 

Absorption of dietary calcium is linked not only to the amount but also to the kind fatty acids in the diet of infants. In a controlled study, the fatty acid composition in one experimental formula was adjusted to simulate human milk, but the structure was dissimilar because the Ci6 o in the formula was mostly at the sn-3 rather than the sn-2 position. The greatest loss of calcium in the feces occurred when formulae with the wrong proportions of Ci6 0 and Ci8 o were fed. Fat absorption and calcium retention were highest in infants fed human milk, followed by infants fed formulae containing a high level of Ci2 o (Nelson et al., 1996, 1998). 

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