Human bones are rigid and strong due to the presence of phosphorus and calcium; these two minerals form much of the strong structural framework or skeletal system in the human body. Approximately eighty five per cent of the human body's phosphorous is held in the skeletal tissues. The remaining phosphorous is found in various bodily fluids and in almost every cell of the body taking part in metabolism and important enzymatic reactions of all types. Phosphorous is required by almost every single metabolic process in the human body, it plays the main role in all biochemical energy production as part of ATP, and this includes the production of energy in the muscles. The mineral is also involved in the biochemical reactions governing the metabolism of carbohydrates, fatty acids as well as in protein metabolism, it forms an essential component of the blood chemistry, it is involved in nervous tissue metabolism, in the transport of fatty acids in the body as well as taking part in numerous enzyme system reactions. A dangerous demineralization of the bones is induced by a deficiency of phosphorus; a deficiency during development also causes the formation of defective bones in children and teenagers. There is a direct correlation between vitamin D and phosphorous, as the vitamin regulates the absorption of phosphorus from the food, this mineral is also involved in the intake of calcium; therefore a vitamin D deficiency can cause a deficiency of phosphorus as well. Several disease states also cause a deficiency of phosphorus, these include pathologies such as alcoholism, problems related to malabsorption, problems related to diabetic ketoacidosis as well as sepsis and renal defects. Disorders like hyperthyroidism, osteoporosis due to disuse and hyperparathyroidism can also cause a phosphorous deficiency. A depletion of the mineral phosphorous can also be induced by long term intravenous glucose therapy and the constant use of antacids.

All cells in the body require phosphorus and this element is an essential mineral for the normal functioning of the human body. Almost all the phosphorus in the human body is found as one of the chemical forms of phosphorous called phosphate - PO4-ions. The human skeletal system contains approximately 85% of the body's total phosphorus with the rest involved in different biochemical functions in the human body.

The skeletal system contains phosphorus in the form of a calcium phosphate salt called hydroxyapatite - this form of the mineral is the major structural component of all bones. A type of combination lipid and phosphorous molecule called phospholipids - such as phosphatidylcholine - is one of the major structural components of all cell membranes in the living world. In the human body, almost all the energy production reactions and energy storage pathways are dependent on the phosphorylation of compounds - the main compounds involved are adenosine triphosphate - or ATP, and the compound called creatine phosphate in muscles. Phosphorous also takes part in the formation and structure of the nucleic acids -DNA and RNA), these nucleic acids are responsible for the storage and transmission of genetic information and make up the genes and chromosomes in the human body, nucleic acids can be described as long chains of phosphate containing molecules. The activation of a large number of molecules such as enzymes, hormones and many of the molecules involved in cell signaling depend on phosphorylation reactions. The maintenance of a normal acid-base balance (pH) in the body is also largely dependent on phosphorus and this mineral has a role as one of the body's most vital physiological buffers. Oxygen delivery to cells and tissues is also regulated by the actions of the phosphorus containing molecule 2, 3-diphosphoglycerate-2, 3-DPG, which binds to hemoglobin in red blood cells during oxygen transport processes in the blood.

The evidence from a recent study involving eleven adult men showed that a diet rich in the sugar fructose - as 20% of total calories consumed - led to an increased phosphorous loss though urine and resulted in the test subjects showing a negative phosphorus balance in the body - which can be explained as a higher daily loss of phosphorus than what was consumed daily during the trial. If the dietary intake was lacking in or had low levels of the mineral magnesium the effect tended to increase. The absence of a biochemical feedback inhibition in the conversion of fructose to the related compound fructose-1-phosphate in the liver is a possible biochemical pathway for this effect. This can simply be stated as the utilization of large amounts of phosphate as the enzyme that phosphorylates fructose is not inhibited by the increased accumulation of fructose-1-phosphate in the cell. The term phosphate trapping is applied to this bio-chemical phenomenon. The discovery of this phenomenon is highly relevant today, as the consumption of fruit sugar-fructose has been increasing rapidly in the U.S. ever since the introduction of high fructose corn syrup in the 1970's, at the same time, the average American diet has less magnesium - and the intake of this mineral has declined over the past century since records were first kept.

The main site for the absorption of dietary phosphorus is the small intestine; the job of the kidney on the other hand is to excrete any excess phosphorus absorbed from dietary sources. The parathyroid hormone (PTH) and vitamin D work to regulate levels of blood calcium and phosphorus - the level of one mineral being related to the level of the other. For example, even a slight lowering of calcium levels in the blood as can occur due to inadequate calcium intake in the diet, will trigger pathways in the parathyroid glands - this will result in an increased secretion of PTH into the blood stream. Biochemical conversion of the vitamin D into its active form, called calcitriol, in the kidneys is stimulated by the PTH hormone. An increase in the absorption of calcium and phosphorous results from an increase in the blood levels of the compound calcitriol. Bone resorption is stimulated by the combined actions of the PTH and vitamin D, this results in the release of the main bone minerals - calcium and phosphate into the blood stream. Two actions are performed from the stimulatory actions of PTH - one is the lowering of calcium excretion in urine, and the second is an increase in the phosphorous excretion in the urine. The loss of phosphorus at a high rate in the urine is helpful in raising the levels of calcium in the blood to normal amounts, this actions is possible as the high blood levels of phosphate leads to the suppression of vitamin D conversion into its active form calcitriol in the kidneys. Therefore, the levels of phosphorous directly influence calcium levels in the body and vice versa.

Modern diets contain ever increasing amounts of phosphates, this is due to the large amounts of phosphoric acid used in popular soft drinks as well as phosphate additives found in many of the commercially prepared foods - this increase in dietary phosphates is a cause of concern to some clinical investigators. The total serum phosphate levels are raised slightly particularly after meals as the level of phosphorus is not as tightly regulated as the level of calcium by the human body. The production of the active form of vitamin D-calcitriol that occurs in the kidneys is suppressed by high phosphate levels in the blood, this leads to a reduction in the total blood calcium levels. This results in an increased release of PTH by the parathyroid glands. A decrease in the urinary excretion of calcium also results from high serum phosphorus levels. The bone mineral content can be adversely affected by elevated PTH levels if the effect is sustained over some period of time, however, this effect has only been noticed in people who consumed diets high in phosphorus and low in calcium. Low calcium diets in general seem to induce similar elevated PTH levels in the body have even when such diets were low in phosphorous as well. Several young women were tested in a controlled trial quite recently, during the course of which they were given a high phosphorus diet - at doses of 3,000 mg/daily, the results showed no adverse outcome from this increase in the mineral on bone related hormones or on the bio-chemical markers of bone resorption if dietary calcium intakes were constantly maintained at approximately 2,000 mg/daily while phosphorus was being supplemented at such high doses. As far as dietary phosphorus levels consumed in the average U.S. home is concerned, there is no present evidence that indicates it has any adverse effect of bone mineral density and the average American diet is therefore not to blame for any phosphorous related health issues. A serious bone health risk and adverse effects on bone health, is however, posed by the substitution of phosphate containing soft drinks and snack foods for milk and other foods rich in calcium in the modern diet.

In addition, abnormally low serum phosphate levels resulting in a condition termed hypophosphatemia can affect a person with inadequate dietary intake of phosphorous. Some of the physical effects of the condition hypophosphatemia can include anemia, generalized muscular weakness, a persistent loss of appetite, bone pain, rickets in affected children, osteomalacia in affected adults, persistent numbness and tingling sensations in the extremities and an increased susceptibility to infections as well as a difficulty in walking or moving about. Death is the eventual result of long term severe hypophosphatemia unless treatment is given to the affected individual. Dietary phosphorous deficiencies tend to be seen only in cases of near or absolute starvation, this is due to the widespread availability of the mineral in the average diet. Certain people are more susceptible to developing hypophosphatemia, the risk of this condition is higher in alcoholics, many diabetics who are recovering from an episode of diabetic ketoacidosis are also at risk, also at risk are many starving or anorexic patients put on re-feeding regimens using foods that are high in calories but low in their phosphorus content.

Since all living organisms on the earth need phosphorus as a critical component in many physiological functions, the mineral is found in most foods and there is consequently no lack of dietary sources for the mineral. Good sources of the mineral phosphorus include all kinds of dairy products, all meats and poultry, nuts and fishes. In addition, to the excellent sources of phosphorus just mentions, the mineral is also found in many polyphosphate food additives as a major component. It is also present in almost all soft drinks as phosphoric acid. Most databases on food do not list dietary phosphorus derived from food additives and the minerals in such additives is normally not calculated, therefore there is no clarity about the total amount of phosphorus consumed by the average person in the U.S. The average intake of phosphorus intake by men in the U.S was found to be 1,495 mg a day as per the results of a large nutrient consumption survey carried out some time ago - the average intake of phosphorus intake in women was 1,024 mg/daily, men generally consumed higher amounts of the mineral than did women as per the results. It is estimated by the Food and Nutrition Board that the consumption of phosphorus in the U.S. has increased from 10% to 15% over the past 20 years across all age groups and sexes.

A biochemical storage form of phosphate called phytic acid or phytate is the chemical form of phosphorus present in all plant seed - for example, beans, peas, cereals and all nuts contain this form of the element. Humans can utilize approximately fifty percent of the phosphorus from the chemical form of phosphorous called phytate as the human body lacks the enzymes - called phytases alter phytates into phosphorous ions which can be utilized by the body in physiological processes. Phytases are also found in yeasts, therefore there is more phosphorous made bio-available in whole grains incorporated into leavened breads than there is in whole grains incorporated into breakfast cereals or used to make unleavened flat breads of all kinds.

The calcification of soft tissues - most commonly the kidneys, can be considered to be the most severe side effect of an abnormal elevation in the blood levels of phosphate as occurs during hyperphosphatemia. Organ damage is the ultimate result of such calcium and phosphate deposition in an organ, this form of kidney damage is dangerous and can be fatal for the affected person. As excess phosphate is very efficiently eliminated by the kidneys from the circulation, the disorder of hyperphosphatemia arising due to dietary causes is a problem primarily for people affected by kidney failure - people at the ending stage from malignant renal disease or hypoparathyroidism are often affected by this problem. Even the ordinary amounts of dietary phosphorus can lead to hyperphosphatemia if the kidneys are only performing at twenty per cent of normal functioning. Cases of very pronounced hyperphosphatemia have also been recorded where the disorder arose due to a greatly increased intestinal absorption of phosphate salts taken orally, such cases also arose due to a greater colonic absorption of the phosphate salts commonly found in enemas. Healthy individuals should according to statements released by the Food and Nutrition Board limit their phosphorous intake to standard tolerable upper intake level (UL) tables put up by them so as to avoid all the adverse effects of hyperphosphatemia. Those individuals over seventy years of age and over have a low UL - that suggests the greater likelihood of impaired kidney function in people who are seventy years and over. There are no UL for those individuals already affected by significant levels of impairment in the functioning of the kidneys or those already suffering from other types of health conditions that are known to increase the chances of hyperphosphatemia developing in the body.

Usual dosage

Phosphorous has a recommended RDA of 700 mg per day for all adults. Most people received enough phosphorous from a variation in the typical diets, a number of the multi-vitamin or multi-mineral supplements possess more than 15% of the current RDA for phosphorus and such supplements must be used only under medical supervision.

Supplemental regimen for older adults - those 65 years and over. There is presently an absence of scientific evidence that suggests a difference in phosphorus requirements of older adults - typically the requirement is 700 mg daily across all age groups. A varied diet is the best source of phosphorous for all individuals even though several of the multi-vitamin or multi-mineral supplements contain more than 15% of the current RDA for phosphorus.

Side effects and cautions

The absorption of dietary phosphorous is reduced significantly by the consumption of aluminum containing antacids by the continual formation of aluminum phosphate, a compound that is not absorbable by the body. Aluminum containing antacids consumed in high doses can also lead to the development of abnormally low phosphate levels in the blood-ending in the disorder called hypophosphatemia, such as situation may also aggravate a pre-existing deficiency of phosphate attributable to other causative factors. The total serum phosphate levels can be significantly reduced by the use of as little as an ounce of aluminum hydroxide gel thrice daily for several weeks - this can also lead to an increase in the loss of calcium in the urine. The disorder called hyperphosphatemia can also develop on the consumption of very high doses of calcitriol, which is the active form of the vitamin D; the use of chemical analogs of calcitriol can also induce this disorder.

Combination of phosphate supplements with high doses of potassium supplements or with the use of potassium sparing diuretics can result in very high levels of potassium - hyperkalemia - in the blood, this is a dangerous disorder. The disorder called hyperkalemia can lead to life threatening heart rhythm abnormalities - arrhythmias - in the person and this is indeed a serious health issue. The serum potassium levels of individuals using such a supplemental combination needs to be checked on a regular basis and they must ensure their health care provider is informed of the supplementation regimen -ideally combined supplements where necessary must be carried out under medical supervision.


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