Calcium daily requirement

Vitamins A, D, and E are required by mminants and, therefore, their supplementation is sometimes necessary. Vitamin A [68-26-8] is important in maintaining proper vision, maintenance and growth of squamous epitheHal ceUs, and bone growth (23). Vitamin D [1406-16-2] is most important for maintaining proper calcium absorption from the small intestine. It also aids in mobilizing calcium from bones and in optimizing absorption of phosphoms from the small intestine (23). Supplementation of vitamins A and D at their minimum daily requirement is recommended because feedstuffs are highly variable in their content of these vitamins. 

Silver white, relatively soft metal that is only applied in alloys. Oxygen and water attack pure Ca. The most prominent compound is the oxide (CaO) = burnt calcium, which hardens to calcium carbonate in mortar. Annual production of about 120 million tons. Burnt gypsum (CaS04 0.5 H20) hardens with water. A great step in evolution was the replacement of hard shells of brittle calcium carbonate by an internal skeleton of tough calcium phosphate (hydroxylapatite)-protein composite. Calcium is essential for all life forms. The daily requirement is 0.7-1.0 g. Humans (70 kg) contain 1 kg of calcium. Calcium silicate is the main component of cement. Marble is calcium carbonate in polycrystalline form and the favorite material of sculptors. 

The elements essential for life can be divided into macroelements (daily requirement > 100 mg) and microelements (daily requirement < 100 mg). The macroelements include the electrolytes sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg), and the nonmetals chlorine (Cl), phosphorus (P), sulfur (S), and iodine (I). 

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). 

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). 

Calcium has long been suspected as adversely affecting the bioavailability of manganese. Excessive intakes of calcium or phosphorus have been shown to increase the daily requirements for manganese in swine (3-5) probably due to decreased absorption of this mineral. However, comparatively little information is available on the comparative effects of different sources of calcium on manganese utilization in humans. 

Minerals include sodium, potassium, calcium, phosphorus, magnesium, manganese, sulphur, cobalt and chlorine trace minerals include iron, zinc, copper, selenium, iodine, fluorine and chromium. Their roles may be generalised within the areas of providing structure in the formation of bones and teeth, maintenance of normal heart rhythm, muscle contractility, neural conductivity, acid-base balance and the regulation of cellular metabolism through their activ-ity/structural associations with enzymes and hormones. The daily requirements of minerals can be obtained from a well-balanced diet. 

AFRC Technical Committee report no. 6 (TCORN 6) proposed that the net daily requirement for calcium for maintenance (g/day) of the dairy cow may be calculated as follows ... 

Despite the negative balances that occurred over considerable periods early in lactation, there was a net positive balance over the lactation and dry period as a whole. It has therefore become normal practice to consider the complete lactation in assessing calcium and phosphorus requirements early negative balances are regarded as normal, since no ill effects are evident as long as subsequent replenishment of body reserves takes place, and daily requirements are formulated on the basis of total production over the lactation. However, although the lactation approach is... 

Few foods are rich sources of calcium although fish such as whitebait and sardines, the backbones of which can be eaten, may provide up to 400mg/100g. Otherwise the best sources are milk and milk products such as cheese (Table 11.2). Green vegetables, cereals and pulses also contain appreciable amounts, but their calcium is less well utilized than that of milk. Since cow s milk contains about 0-12g of calcium per 100 ml, half a litre or 1 pint (568 ml) should provide the daily requirement. Calcium deficiency is thus mainly a hazard in countries where milk and cheese are not regularly consumed. 

The daily requirement of calcium for maintenance of health has been computed from balance experiments conducted by many independent observers. In normal healthy adults equilibrium is reached between intake and output when the former is in the region of 0.55 g. daily, but as it is desirable that the intake of calcium should be above the minimum required for balance a margin of 50% is allowed for safety, which brings the requirement of adults to 0.8 g. daily. 

Boron is found in humans and animals. The concentrations in the organs and tissues vary. In human beings, the highest concentrations are found in the heart (28mg/kg), followed by the ribs (lOmg/kg), spleen (2.6mg/kg) and liver (2.3 mg/kg). Muscle tissue contains only 0.1 mg/kg. Boron seems to be an essential nutrient, which promotes bone formation by interaction with calcium, magnesium and vitamin D. In addition, there are indications that boron is involved in the hydroxylation of steroids, e. g., in the s)mthesis of 17P-estradiol and testosterone. The daily requirement is estimated to be 1-2 mg. Apples (40), soy flour (28), grapes (27), tomatoes (27), celery (25) und broccoli (22) are rich in boron (mg/kg solids). Important sources also include wine (8) and water. 

Sherman emphasises the necessity for an adequate intake of calcium in the human diet, especially in the nutrition of children, and places the daily requirement at 0 7 -l 0 gm. 

Vitamin D Standard and Begnirements.— The international standard adopted by the I eague of Nations (1931) is the biological activity of 1 mg. of a standard solution of calciferol in oil. This quantity given daily to a young rat rendered rachitic by a diet free from vitamin D will produce in eight days a characteristic band of calcium deposits in the metaphyses of the long bones. One gm. of crystalline calciferol is equivalent to more than 40,000 international units. The daily requirements of vitamin D needed to prevent or cure mild rickets in children is about 3,000 units, in the form of calciferol, or 1,000 units in the form of liver oil (vitamin Dj). 

The amount of each element required in daily dietary intake varies with the individual bioavailabihty of the mineral nutrient. BioavailabiUty depends both on body need as deterrnined by absorption and excretion patterns of the element and by general solubiUty, and on the absence of substances that may cause formation of iasoluble products, eg, calcium phosphate, Ca2(P0 2- some cases, additional requirements exist either for transport of substances or for uptake or binding. For example, calcium-binding proteias are iavolved ia calcium transport an intrinsic factor is needed for vitamin cobalt,... 

Daily calcium and vitamin D requirements are highest in postmenopausal women and elderly men 1500 mg elemental calcium and 400 to 800 IU vitamin D (see Table 53-4). When these requirements cannot be achieved by diet alone, appropriate calcium and/or vitamin D supplementation is recommended. 

Electrolytes that are included routinely in PN admixtures include sodium, potassium, phosphorus (as phosphate), calcium, magnesium, chloride, and acetate. When determining electrolytes in PN admixtures, the patient s renal function always must be taken into account. Typical daily electrolyte maintenance requirements for adults with normal renal function are listed in Table 97-3. 

VII.a.2.2. Treatment. Treatment of established vitamin D deficiency requires much larger doses of vitamin D, such as calciferol tablets of 1 mg (40,000 units) daily. Newer but more expensive preparations such as alfa-calcidol and calcitriol are very effective, and are particularly valuable in patients with renal failure who are unable to hydroxylate calciferol. Patients treated with pharmacological doses of vitamin D preparations must be monitored by checking serum calcium at regular intervals because of the risk of inducing hypercalcaemia. This should always be suspected if patients develop thirst, nausea or vomiting. The newer hydroxylated preparations have a shorter effective half-life, and therefore problems of overdosage are quicker to resolve once identified. 

Vitamin D preparations are also used to treat hypoparathyroidism, but they require even larger doses, often up to 2.5 mg (100,000 units) daily to increase the serum calcium back to normal. As in vitamin D deficiency, the dose must be carefully monitored. 

Once bone loss is sufficient to result in a compression fracture, pharmacological therapy is much less effective. However, even after fractures have occurred, the use of the bisphosphonates and rPTH has been shown to increase bone densities and reduce the rate of subsequent fractures. Nasal calcitonin (200 units daily) is effective in promoting fracture healing and also exhibits an analgesic effect by reducing pain in persons with acute lumbar compression fractures. Whatever compound is used for prophylaxis or treatment of osteoporosis, calcium and Ds supplementation are required for maximum benefit. 

---