Diets high-calcium

Dietary and pharmacologic agents influence the risk of colon cancer. Diets high in fat and low in fiber are associated with increased colon cancer risk, whereas the regular use of aspirin (and other NSAIDs) and calcium supplementation may decrease the risk of colon cancer. 

A high calcium diet was also shown to influence the toxicity of lead. Dam and pup hemoglobin... 

It has also been demonstrated in animals that lead blocks the intestinal responses to vitamin D and its metabolites (Smith et al. 1981). Dietary concentrations of lead in combination with a low phosphorus or a low calcium diet administered to rats suppressed plasma levels of the vitamin D metabolite, 1,25-dihydroxycholecaliferol, while dietary intakes rich in calcium and phosphorus protected against this effect (Smith et al. 1981). Thus, animals fed a diet high in calcium or phosphorus appear to be less susceptible to the effects of lead, because of hindered tissue accumulation of lead. 

Given drinking water with 10 mg Pb/L for 51 days diets were either low in calcium (0.3% Ca) or adequate in calcium (3% Ca) Birds given low calcium diets accumulated up to 4 times more lead in tissues than finches on high calcium diets. Lead concentrations in mg/kg DW for low Ca vs. high Ca diets were 2.4 vs. 0.6 in liver, 4.9 vs. 1.5 in kidney, and 48 vs. 8 in bone 52... 

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. 

It is noteworthy that although phosphorus absorption was lower on the high calcium, high polyphosphate diet than on the high calcium, high orthophosphate diet, there was no significant difference between... 

Feeding human subjects meat-rich diets has been clearly and repeatedly associated with elevated urinary acid and calcium loss. Anand, et al. (12) fed college men low, medium, and high-protein diets. Fecal calcium changed less than 15%, whereas urinary calcium losses accounted for the major loss of calcium. Calcium loss and meat protein intake correlated directly. Johnson, et al. (34) reported that women showed a similar response when fed such diets. 

Since the early 1970 s, research has been directed at identifying the mechanism by which the calciuria is induced. Attention was given first to the question of whether the elevated urinary calcium excretion was caused by an increase in the intestinal absorption of calcium. Results of calcium balance studies in human subjects showed that protein ingestion either had no effect on calcium absorption (4) or that the effect was insufficient to account for the calciuria (5j. Consequently, negative calcium balance is a frequent observation in human studies when high protein diets are fed, and this situation is not improved by high calcium intakes (4 ). 

Drug/Food interactions Diets high in dietary fiber have been shown to decrease absorption of calcium due to decreased transit time in the Gl tract and complexing of fiber with the calcium. 

Andon, M. B., llich, J. Z., Tzagournis, M. A., and Matkovic, V. (1996a). Magnesium balance in adolescent females consuming a low- or high-calcium diet. Am. ]. Clin. Nutr. 63,950-953. 

The zinc contained in plants is not fully utilized by animals. Diets high in calcium and phosphorus have been associated with poor digestibility of dietary zinc. Diets with large amounts of soy protein are particularly likely to require extra zinc fortification for livestock. Meat is an important source of zinc for human diets. Where supplementation of zinc is indicated, zinc sulfate, zinc oxide, and zinc carbonate are commonly used. 

Osteoporosis is a disease or metabolic disturbance, particularly in postmenopausal women, that indicates a need for a very high dietary calcium intake. High calcium requirements appear to be related to the very high protein intake of the modem Western diet. A decreased protein intake, as can be obtained on a total vegetarian (vegan) diet, can allow for calcium balance, in a variety of age groups, from one third to one fifth the amount of daily calcium required with a Western diet. 

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). 

Gastrointestinal absorption, and subsequent utilization and retention by the body, of essential trace elements such as zinc, copper, and selenium can also be enhanced or diminished by the presence or absence of other trace elements and chemicals in the diet (WHO, 1996). For example, cadmium and lead absorption is enhanced when dietetic intake of calcium, iron, and phosphate is low. Phytate, an organic phosphate that is abundant in diets high in unrefined grains, especially when accompanied by high dietetic calcium, helps suppress the uptake of potentially toxic elements such as lead and cadmium, but also inhibits the uptake of essential zinc (WHO, 1996). 

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