Calcium, content, human body

Most of the forementioned studies which examined the influence of various dietary fiber on the bioavailability of calcium by human subjects have depended upon the comparative measurements of calcium content of diets and calcium contents of stools and urine. As reviewed by Allen (3), calcium balance studies have distinct limitations relative to accuracy and precision. However, their ease of application and cost, laboratory equipment requirements, and real (or perceived) safety in comparison to available radioactive or stable isotope methods continue to make their use popular. In calcium balance studies, calcium absorption is assumed to be the difference between calcium excretion in the feces and calcium intake. Usually this is expressed as a percent of the calcium intake. This method assumes that all fecal calcium loss is unabsorbed dietary calcium which is, of course, untrue since appreciable amounts of calcium from the body are lost via the intestinal route through the biliary tract. Hence, calcium absorption by this method may underestimate absorption of dietary calcium but is useful for comparative purposes. It has been estimated that bile salts may contribute about 100 g calcium/day to the intestinal calcium contents. Bile salt calcium has been found to be more efficiently absorbed through the intestinal mucosa than is dietary calcium (20) but less so by other investigators (21). 

Although bone is not considered a major calcium sensing organ in humans, the cells of bone tissue control over 99% of the human body s calcium content. The principal calcium sensors that regulate bone calcium uptake and release are in the parathyroid glands. Bone function is also modified by vitamin D and by calcium transport in the kidney and intestine. These indirect mechanisms of controlling bone calcium metabolism are beyond the scope of our considerations here. In spite of processing... 

Like nitrogen, phosphorus is an element that is essential to life. It constitutes only about 1 percent by mass of the human body, but it is a very important 1 percent. About 23 percent of the human skeleton is mineral matter. The phosphorus content of this mineral matter, calcium phosphate, Ca3(P04)2, is 20 percent. Our teeth are basically Ca3(P04)2 and Ca5(P04)30H. Phosphates are also important components of the genetic materials deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). 

Sea lettuces which draw from the sea contain wealth of mineral elements (Table 5.4). Calcium, one of the most important minerals essential for human body, is accumulated in sea lettuces at a higher level compared with milk, brown rice, spinach, peanuts, and lentils (MacArtain et ah, 2007). Calcium contents in Ulva lactuca, Ulva reticulata, Ulva fasciata were 32.5, 147, and 0.47 mg/100 g edible portion, respectively. Moreover, potassium and sodium are known as electrolytes because their ability to dissociate into positively and negatively charged ions when dissolved in water. Potassium is the major cation of intracellular fluid. Together with sodium, it maintains normal water balance. In addition, potassium also promotes cellular growth and maintains normal blood pressure. Potential source of potassium is Ulva reticulata, which contains 1540 mg potassium per 100 g edible portion (Ratana-arpom and Chirapart, 2006). 

The content of magnesium in the body of an adult is about 25-40 g. This accounts for about 60% of the content of the skeleton. The highest concentrations of magnesium in soft tissues are found in the pancreas, liver and skeletal muscles. Blood and extracellular fluids contain only 1% of the total amount of magnesium in the body. Calcium is quantitatively the major mineral component in the human body. The total amount is about 1500g, with 99% of this being in bones and teeth as calcium phosphate. 

CEdcium is the most abundant mineral present in the body. In an adult man, the total content of calcium is about 1-1.5 kg. It is mostly present in bones and teeth in the form of calcium phosphate and calcium carbonate. The concentration of calcium in bones and teeth is 20 mg lOO gm and its concentration in the serum of blood is 9-11 mg/100 ml. Calcium is also present in the soft tissues of body, extra-cellular fluid and plasma. The richest source of calcium is milk and cheese. It is also present in beans, cabbage, turnip, green vegetables, nuts and egg yolk. Adult human being needs about 800 mg calcimn per day while the growing children and pregnant women may need about 1.5 gram per day. 

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