Calcium requirements

Factors I, II, III, V, VII, VIII, IX, X, XI, XII, and XIII, Protein C, and Protein S are synthesized in the Hver. Factor III is present in many different organs throughout the body. Factor IV is the divalent cation calcium. The concentration of calcium required for normal function of the blood coagulation system is much less than required for normal physiologic function of many organs in the body, eg, myocardium. 

Calcium supplements are available in a variety of calcium salts and dosage forms. Calcium requirements are listed in terms of elemental calcium. However, many product labels list calcium content in the salt form, so the percent of elemental calcium must be known to calculate the elemental calcium content per tablet. 

Sodium, potassium, magnesium, and phosphorus requirements are typically decreased in patients with kidney failure, whereas calcium requirements are increased (see Chaps. 76 and 78). 

The concept of bioavailability was developed to explain the difference between the total amount of mineral in a food and the amount which was used by the individual consuming the food. Over the past sixty years or more, there have been numerous studies related to dietary calcium requirements and bioavailability (1,2). As a result, much is known about non-calcium food components which influence the absorption and utilization of dietary calcium under experimental conditions. What now is lacking is a detailed knowledge of how these factors interact with calcium under normal conditions of ingestion in meals. 

An attempt was made to collate data on human and rat apparent calcium absorption values for several calcium sources. Absorption values were so variable within species and calcium sources that a correlation could not be justified. Much of this variability may be due to methodological differences between the design of the rat and the human experiments. Most of the animal experiments were conducted using rapidly growing rats which were fed modest amounts of calcium but which have high calcium requirements. 

We have not completed the analyses of self-chosen diets consumed by the subjects in HS-II and HS-III, but preliminary indications are that there was a wide range in intakes of calcium and of phytate/ calcium molar ratios. Stools and urine were collected while the self-chosen diets were being collected. Comparison of calcium metabolic balance parameters when consuming the self-chosen diets and the controlled diets of HS-II may provide an insight on dietary calcium requirement by these individuals. Some advocate the present RDA of 800 mg for adult men is too low (17), however, unpublished (R.D. Reynolds et al.) data from dietary intakes in a developing country indicate much lower usual intakes of calcium with relatively high phytate/calcium molar ratio. 

Malm, O.J. "Calcium Requirement and Adaptation in Adult Men" Oslo University Press Oslo, Norway, 1958. 

Calcium Requirements WORLD HEALTH ORGANIZATION TECHNICAL REPORT SERIES No. 230, WHO Geneva, 1962 pp. 16-18. 

Reactions of aryl halides with the reactive calcium required slightly higher temperatures, up to -30°C for aryl bromides and up to -20°C for aryl chlorides.1 2 3 4 5 Surprisingly, the active calcium reacted readily with fluorobenzene at room temperature to form the corresponding organocalcium reagent in near quantitative yield. 

It is noteworthy that, unlike the previously described induces of PTPC opening, GD3 is able to exert its effect on mitochondria even in the presence of submicromolar calcium concentration (Kristal and Brown, 1999a), a property shared only by the most potent PT inducers, such as the thiol cross-linking agent phenylarsine oxide and by the peptide mastoparan. This low calcium requirement is important because intracellular calcium concentration during CD95-mediated apoptosis was not described to rise above 0.4 pM (Oshimi and Miyazaki, 1995). 

Matkovic, V. (1991). Calcium metabolism and calcium requirements during skeletal modeling and consolidation of bone mass. Am. J. Clin. Nutr. 54, 245S-260S. 

Prentice, A., Jaqou, L. M., Cole, T. J., Stirling, D. M., Dibba, B., and Fairweather-Tait, S. (1995). Calcium requirements of lactating Gambian mothers Effects of a calcium supplement on breast-milk calcium concentration, maternal bone mineral content, and urinary calcium excretion. Am. J. Clin. Nutr. 62, 58-67. 

Wade, M. A. (2004). Calcium The chosen form Fortifying products with calcium requires an understanding of the benefits of various forms and their interactions. Prepared Foods 175, 54-58. 

Magnesium is also of interest as a replacement for Ca(ll) in calcium-requiring enzymes. In some of these, the replacement is simple (Lewinski and Lebioda, 1986), and in others it cannot occur. NMR studies show that magnesium can bind in the calcium sites of troponin C (Tsuda et al., 1990). The structure of turkey skeletal muscle troponin C has recently been reported (Herzberg and James, 1985). In one domain the replacement of Ca(II) by Mg(II) causes a conformational change, but in the other domain it does not. 

As the Kawasaki research team mentioned earlier nave concluded, there is also, with calcium, a Ca/S requirement as with the REM S for total MnS substitution 32), They have proposed the most reliable estimate so far of retained calcium requirement for "homogeneous sulfide shape control" which is summarized in Table IV and Figure 17. 

Smooth muscle responses to calcium influx through receptor-operated calcium channels are also reduced by these drugs but not as markedly. The block can be partially reversed by elevating the concentration of calcium, although the levels of calcium required are not easily attainable. Block can also be partially reversed by the use of drugs that increase the transmembrane flux of calcium, such as sympathomimetics. 

Spencer, H., Kramer, L., Lesniak, M., Debartolo, M., Norris, C. and Osis, D. 1984. Calcium requirements in humans. Report of original data and a review. Clin. Orthop. 184, 270-279. 

The combination of rifampicin and isoniazid reduces serum concentrations of 25-hydroxy cholecalciferol. Rifampicin acts by induction of an enzyme that promotes conversion of 25-hydroxycholecalciferol to an inactive metabolite, and isoniazid acts by inhibiting 25-hydroxyla-tion and 1-hydroxylation (SEDA-14, 258). Children or pregnant women with tuberculosis have increased calcium requirements independent of rifampicin administration... 

REGULATION OF CALPAIN ACTIVITY. THE CALCIUM REQUIREMENT PROBLEM... 

Pontremoli, S., Melloni, E., Viotti, PL., Michetti, M., Di Lisa, F., Siliprandi, N., 1990, Isovalerylcarnitine is a specific activator of the high calcium requiring calpain forms, Biochem. Biophys. Res. Commun., 167, 373-380... 

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. 

The recommended ratio of phosphorus to calcium is 1 1, except in infants it is 2 1. For older infants, the recommended intake of phosphorus is increased to 80% of the calcium requirement, so that the ratio is similar to cow s milk (Harper 1969). Both phosphorus and calcium are distributed similarly in foods, hence a sufficient intake of calcium ensures a sufficient intake of phosphorus. The exception is cows milk, which contains more phosphorus than calcium (Harper 1969). The adult daily requirement for phosphorus is about 700 mg. A balanced diet provides sufficient amounts of phosphorus because it is commonly found in foods (phosphoproteins and phospholipids, inorganic phosphate), especially milk and milk products, wheat, meats and fish (Latner 1975). In the body, normal serum (inorganic) phosphorus levels are 4-7 mg/100 mL in children and 3-4.5 mg/100 mL in adults and the elderly. In body fluids and tissues, normal serum phosphorus levels found are 40, 170-250, 360, and 22,600 mg/100 mL in blood, muscle, nerve, and both bones and teeth, respectively (Harper 1969 Tietz 1970). 

CC Leslie, JY Channon. Anionic phospholipids stimulate an arachidonoyl-hydrolyz-ing phospholipase A2 from macrophages and reduce the calcium requirement for activity. Biochim Biophys Acta 1045 261-270, 1990. 

The response to signaling is also shown in a progressive way. Keratinocytes grown in a low-calcium media proliferate. Increased extracellular Ca2+ inhibits proliferation, while it induces differentiation.11 On the other hand, differentiation of keratinocytes causes a decrease in responsiveness to extracellular calcium, which may facilitate the maintenance of the high level of intracellular calcium required for differentiation.12... 

The human organism contains 1-1.4 kg calcium, and about 1% of this is in the extracellular fluid. The rest is largely in bone. The serum calcium concentration is 9-11.5 mg/dL, of which 4.5-5.0 mg/dL is in the free, ionized, biologically active form. The rest is protein bound or complexed with a variety of chelators, such as citrate. The daily dietary calcium requirement is 400-500 mg, and each day, 300-400 mg calcium is lost in the urine and an additional 150 mg in the feces. Inorganic phosphorus (largely as HP042 ) amounts to 2.7-4.5 mg/dL in adult serum. 

Another nonlysosomal protein degradative system is dependent on calcium ions. They combine with specific protein residues in close proximity to each other proline, glutamate, serine, and threonine (PEST sequences). It is believed that a calcium-requiring proteinase (a metalloenzyme) recognizes the calcium and combines with it, thus achieving an active status, and then hydrolyzes the protein in the vicinity of the PEST sequence. 

Today, there are several heat stable alpha amylase products on the market, many of which were tailored using mutation and recombinant DNA techniques. A major tailoring target has been improvements of yield during enzyme production in order to be more cost effective in the marketplace. All of the heat stable alpha amylases require calcium for stabilization which must be added to the starch slurry and then removed by ion exchange later in the process. The calcium requirements vary widely. For example, the amylase from B. licheniformis requires only 5 ppm calcium while the... 

---