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Zinc is an essential trace mineral found in the body in larger amounts than any other trace mineral, 1.8 grams, except iron, 5 grams. It has been recognized as essential to humans in 1960s when deficiency cases were first recognized. The mineral is absorbed throughout the small intestine mostly in the jejunum and absorption is influenced by the type of foods ingested. Absorption is more likely to be high if animal proteins are consumed, when body needs are higher and when dietary intake is low.

When absorption take place into intestinal cells a protein, metallothionein, binds zinc in similar way that ferritin binds iron and partly regulates its absorption. The largest stores of this trace mineral in the body are found in the pancreas, liver, voluntary muscles, and bones. It is also found in the eyes, skin, prostate gland, hair nails, and white blood cells. However, the absorbed amounts of the mineral in the body are classified as functional zinc and amounts held in storage are very small.

Zinc intakes are generally low worldwide. While insufficient dietary intake may be the cause of poor zinc status in some cases the most likely causative factor in depleted zinc status are inhibitors of its absorption. A high intake of phytic acid found in grains and high intake of calcium both decease absorption of this mineral. Some milk proteins have been shown to inhibit its absorption. Finally zinc competes with copper and iron in the body for absorption.

Zinc is present in every cell in the body and has many and diverse biological functions. More than 100 require zinc for optimal activity. The mineral supports many body functions such as: Protein metabolism, immune function, general growth, wound healing and burns, synthesis and function of nucleic acid, development of sexual organs, insulin function cell membranes structure and function and behavioral development in infants.
Severe deficiency is not common but marginal deficiency of zinc is and it is difficult to diagnose.

The signs and symptoms of deficiency are nonspecific and can include increased fatigue, decreased alertness, and inadequate growth, declined immune function, acne, delayed wound healing, decreased production of lymphocytes and decreased B and T lymphocyte responses. A high intake of this mineral interferes with copper and iron metabolism and increases the need for vitamin A intake.

The RDA for zinc is 11 mg/day for men and 8 mg/day for women and the upper level is 40 mg/day. In general protein rich diets are rich in zinc also. Foods with high content are oysters shrimp, beef, turkey, legumes. Nuts, whole grains, wheat germ and pumpkin seeds can provide substantial amounts. While food sources for zinc are the preferred sources, zinc supplements shown to be effective to maintain zinc status in those at risk of deficiency.

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Magnesium is an essential mineral that accounts only for 0.05 percent of the body’s total weight. Approximately 70 percent of the mineral is located in the bones and the rest in soft tissues such as muscles and in body fluids. Magnesium, like calcium is a cation (divalent). It is heavily involved in many metabolic processes and it is widely distributed in foods especially green leafy vegetables. It’s an essential element of chlorophyll.

Approximately 50 percent of the magnesium from dietary sources is absorbed in the small intestine through passive and active absorption. The rate of absorption is influenced by the parathyroid hormones and the amount of calcium, phosphate and lactose in the body. High magnesium intake reduces the rate of absorption and low intake increases the rate. Aldosterone a hormone produced by the kidneys regulates the rate of magnesium loss through kidneys. Diuretics and alcohol increase magnesium loss in the urine.

Magnesium plays an extensive and vital role in many biological and physiological processes. It is responsible for more than 300 enzymatic reactions in the body and its presence is required in many energy-yielding compounds in cells, ATP. It also contributes to the DNA and RNA synthesis, in bone structure by abiding calcium and potassium metabolism, nerve and heart function, insulin release from pancreas, decreasing blood pressure and prevention with heart rhythm abnormalities.

Magnesium also helps to promote the absorption of other minerals such as phosphorus, calcium, potassium and sodium and the utilization of the B-complex vitamins and C and E. The conversion of blood sugar in to energy it needs sufficient amounts of magnesium and for the regulation of body temperature. High cholesterol levels and high intake of proteins increases the need for this mineral. Magnesium also helps to prevent accumulation of calcium and phosphorus deposits in the urinary tract by keeping them soluble.

Approximately 50 percent of dietary magnesium comes from green leafy and other vegetables, fruit and grains and 30 percent from milk and its products, eggs and chocolate. The Recommended Daily Allowance is 310 mg/ day for adult women and 400 mg/day for men. Magnesium deficiency develops very slowly. The need of magnesium increases slightly with some individuals over the age of 30.

Toxicity it is not a problem in healthy people with a typical diet. However, large amounts can lead to diarrhea and toxicity can occur from not food source magnesium in older individuals, in the event of kidney failure or if kidney functions is compromised.

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Calcium is the most abundant of all the minerals in the human body. While every cell need calcium 99% of calcium is used in the structure of bones and teeth. It represents more than 40% of all the minerals in the body or the equivalent of 1.2kg. For proper function calcium needs the presence of the minerals magnesium, phosphorus and vitamins A, C, and D. The main action of calcium is the build up and maintenance of bones and teeth.

Calciumis absorbed primarily in the upper part of the small intestine since it needs a pH below 6 to stay in solution. Humans absorb about 25% of the ingested calcium from foods and several factors enhance the amount absorbed include Age; younger people have a better absorption than older people, presence of sufficient active vitamin D [1, 25 (OH) 2 D]; parathyroid hormone; dietary lactose and glucose; and normal intestinal flow.

Factors that limit absorption of calcium include age; postmenopausal women in general absorb the least calcium, excessive dietary phosphorus; deficiency in vitamin D; excessive dietary fiber (phytic acid); tannins in tea; and the presence of chronic diarrhea. Cells in the body have a critical need for calcium. Calcium is present in a very limited number of foods such as milk and dairy products but in a significant amount.

When levels of calcium in the blood fall, the parathyroid hormone together with vitamin D increase the retrieval of calcium through the kidneys before it is excreted. Additionally, both influence the release of calcium from bones to maintain calcium levels in the blood normal. When levels of calcium in the blood are too high the parathyroid hormone and vitamin D levels fall. Excretion of calcium through kidneys increases and secretion of the hormone calcitonin from the thyroid gland decrease the loss of calcium from bones and cause blood levels of calcium in the blood to remain normal.

Calcium participates in several reactions including the process of blood clotting, balance of pH in the blood, muscle growth, contraction and nerve transmission. It also helps in the utilization of iron, activation of several enzymes, regulation of nutrient passing through the cell walls and helps metabolism in cells (calmodulin system). Calcium may also contribute in the lowering of blood pressure, reduce the risk of colon cancer, lower blood cholesterol and reduce the risk of kidney stones.

The most common calcium related disease is osteoporosis. Women are at a higher risk than men in suffering osteoporosis, especially menopausal women. However, both older men and women need to stay physically active and meet the adequate intake of calcium for adults, 1000 to 1200 mg/day. Upper levels for calcium are 2500 mg/day. Calcium supplements can be taken by people that don’t drink milk or dairy milk products.

Toxicity from calcium is unlikely as the small intestine prevents excess calcium from being absorbed. However, in the event that the system breaks down excess calcium concentrations may lead in the calcification of kidneys, kidney failure, kidney stones, prostate cancer and interferences in absorption of other minerals. Calcium present in every day foods does not pose any risk. Individuals using excessive amounts of supplemental calcium can be at risk.

calcium

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