Loss of bone calcium

Four of the main-group cations are essential in human nutrition (Table A). Of these, the most important is Ca2+. About 90% of the calcium in the body is found in bones and teeth, largely in the form of hydroxyapatite, CatOH)2 - SCa PO. Calcium ions in bones and teeth exchange readily with those in the blood about 0.6 g of Ca2+ enters and leaves your bones every day. In a normal adult this exchange is in balance, but in elderly people, particularly women, there is sometimes a net loss of bone calcium, leading to the disease known as osteoporosis. 

The rat has been used rather widely to study the relation between dietary protein, or acid salt feeding, and calcium loss. Barzel and Jowsey (19) showed that the rat fed a control diet supplemented with ammonium chloride excreted excessive urinary calcium, and experienced a concomitant loss of fat-free bone tissue. Draper, et al. (20) extending this work, reported an inverse relation between dietary phosphate and loss of bone calcium and dry, fat-free tissue. In subsequent studies (21), they reported that this process was accompanied by reduced serum calcium levels the high phosphorus, low calcium diet increased urinary calcium loss. Whereas, increasing the phosphorus content of the diet stopped the excessive urinary calcium loss. To test possible zinc loss that might result from this sort of acid salt feeding, Jacob and her coworkers (22) fed rats a supplement of ammonium chloride and then measured urinary zinc and calcium. The hypercalciuria occurred exclusive of an effect upon urinary zinc loss. 

Effect on Electrolytes. The administration of human growth hormone raises the intracellular levels of electrolytes, leads to a loss of bone calcium, and reduces urinary levels of phosphorus, potassium, and sodium. The increase in intracellular electrolytes may result from an increase in the cellular mass. Mobilization of bone calcium leads to osteoporosis in acromegaly and calciuria. Two explanations offered for this are (1) increased glomerular filtration combined with inhibition of tubular reabsorption, and (2) stimulation of parathyroid secretion. 

A condition which clinically resembles osteomalacia. It differs from osteomalacia, however, in that it is due to a primary loss of the proteinaceous bone matrix with a resultant secondary loss of bone calcium. It can occur as part of the general process of ageing, or in conditions such as hyperthyroidism, acromegaly, Cushing s syndrome (because of the effects of thyroxine, growth hormone and cortisol on protein metabolism) and malabsorption (due to deficient amino acid absorption). Serum calcium, phosphate and alkaline phosphatase levels are normal, unlike osteomalacia. 

The bone becomes depleted of calcium salts when the urine is acidic over a relatively long period. This was shown by Goto (17) who fed rabbits large doses of hydrochloric acid. He then showed that urinary calcium loss occurred in concert with a marked reduction in mass of the skeletal system, and also that the total non-fat dry weight of bone decreased,implying a loss of bone matrix. A dose-dependent, dietary acid induced loss of labelled calcium from rat bone has been reported by Thorn and his coworkers (18). They demonstrated that in response to graded doses of ascorbic acid, cells in tissue culture, and bones in whole animals fed such doses were depleted of the labelled calcium. 

Meat consumption was accompanied by more sulfate output in the urine. This agrees with earlier feeding studies in which animals were fed any of several fixed acids which had been reported to result in increased calcium loss (13, 17). Feeding hydrochloric acid, Goto (17)showed that calcium carbonate was simultaneously lost from the bones of rabbits. A similar conclusion was drawn by Steenbock, et al. (13) who demonstrated a loss of both calcium and phosphorus mediated by hydrochloric acid. These data were consistent with the sulfate infused dog. In the dog, Walzer and Browder (15) showed that sulfate feeding increased calcium losses along with sulfate loss. This confirmed results that Lamb and Evvard (32) reported for the Pig-... 

Although much attention has been directed toward the relationship between calcium intake and osteoporosis, little consideration has been given to the possible influence of dietary phosphorus on the development of this disease in either man or animals. In a study designed to determine the optimal concentration of calcium and phosphorus in the diet of adult mice, aging animals were found to undergo a greater loss of bone when the Ca/P ratio was 1 1 than... 

As we age, the activity of osteoclasts tends to outrun that of osteoblasts, leading to gradual loss of bone and increasing susceptibility to bone fracture. In the elderly, a hip fracture has about the same mortality rate as a heart attack. Crush fractures of vertebrae lead to an abnormal curvature of the spine and an inability to stand up straight. So, exercise and get enough calcium and vitamin D in your diet. 

She should be encouraged to take calcium and vitamin D supplementation immediately. She should be scheduled for baseline determination of her bone density so that any evidence of loss of bone mass can be ascertained. 

A less common circumstance leading to hypercalcemia is development of a form of bone disease characterized by a profound decrease in bone cell activity and loss of the calcium buffering action of bone (adynamic bone disease). In the absence of kidney function, any calcium absorbed from the intestine accumulates in the blood. Therefore, such patients are very sensitive to the hypercalcemic action of l,25(OH)2D. These individuals generally have a high serum calcium but... 

In addition, gelatin peptides have shown to accelerate absorption of dietary calcium in animal models increasing calcium bioavailability (Kim et al., 1998). Jung et al. (2006) reported that fish bone peptides (FBP) could inhibit the formation of insoluble Ca salts in neutral pFI. During the experimental period, Ca retention was increased and loss of bone mineral was decreased by FBP II supplementation in ovariectomized rats. The levels of femoral total Ca, bone mineral density, and strength were also significantly increased by the FBP diet to levels similar to those of the casein phosphopeptide diet group. 

Calcium (Ca2+) Bone and tooth formation, nerve and muscle function Retarded growth, possi ble loss of bone mass... 

Protein, calcium, vitamins A and D needed to prevent the loss of bone minerals that frequently occurs with increasing age... 

Estrogen decreases frequency of hip fracture. [Note Dietary calcium (1,000 to 1,500 mg daily) and weight-bearing exercise also slow loss of bone.]... 

Calcium needs and metabolism have become an important nutrition issue due to the increased prevalence of osteoporosis. Osteoporosis is a disease of fragility of major bones such as the pelvis, femur, and spine caused by an age-related loss of bone minerals. As discussed in Chapter 7, calcium intake and physical activity may favorably affeot the calcium content of bones and delay the onset of osteoporosis. 

Inadequate amounts of dietary calcium contribute to loss of bone mineral density and increased rates of fracture observed in osteoporosis, a disease which afflicts over 40% of postmenopausal women in the developed nations. The primary source of dietary calcium is dairy products (Table 3). The preparation of com meal using calcium hydroxide fortifies this grain. Because the intake of dairy products by adult females is low, their average calcium consumption (550 mg) is well below the recommended 1000 1200 mg. Supplementation with various forms of calcium is pmdent. Fortification of fhiit juices and soft drinks with calcium complexed with citric and malic acids has been achieved. 

Boys and men tend to consume an amount of calcium that meets the RDA however, girls and women tend to consume only half the RD A level (Bronner, 1994 NIH Consensus Development Panel, 1994). Once the peak bone mass has been achie ed, evidence suggests that Ca supplements have no influence on further increasing bone mass. Once menopause has been reached, calcium supplements cannot slow the loss of bone, unless estrogen 5 s also taken (there is some evidence that this statement applies only to trabecular bone, and that cortical bone loss can be reduced by Ca supplements alone (Bronner, 1994)). tn viewing the foregoing considerations, it seems reasonable that a ) parents of girls should be persuaded to take the RDA for calcium seriously for the duration of their childhood and adolescence. 

Estrogens affect calcium homeostasis and have a beneficial effect on bone mass. They decrease bone resorption, and in prepubertal girls estrogen accelerates linear bone growth and results in epiphyseal closure.Long-term estrogen depletion is associated with loss of bone mineral content, an increase in stress fractures, and postmenopausal osteoporosis. ... 

Apart from the increasing need of repair of the ambulatory knee-hip kinematic, an additional serious problem exists osteoporosis. Increasingly, loss of bone substance occurring in elderly people, preferably women, leads to embrittlement with the associated risk of fracture. Among reasons related to complex and not yet fully understood endocrine oestrogen deficiency in women, as well as metabolic, myelogenic and hereditary causes this is to some extent due to lack of calcium possibly related to nutrition too rich in red meat, wheat and modified dairy products that are suspected to produce an acidic environment in the body. Hence, calcium ions taken from the bone substance by osteoclastic resorption are being used to keep... 

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