4-Trace elements-1.pdf

Minerals Metabolism and Trace elements (chemistry and Functions) BY DR J.O.AREOLA  Introduction The human body is composed of elements which can be roughly divided into abundant (macro) elements which include: Magnesium, calcium, potassium, phosphorus etc...

Minerals Metabolism and Trace elements (chemistry and Functions) BY DR J.O.AREOLA  Introduction The human body is composed of elements which can be roughly divided into abundant (macro) elements which include: Magnesium, calcium, potassium, phosphorus etc and trace (micro) elements which include: zinc, copper, iodine, selenium, cobalt, manganese, chromium and molybdenum. Research has shown that deficiency of trace elements are responsible for different types of diseases in man and domestic animals.  Magnesium (Mg2+) Magnesium is one of the most important cations in living cells. Mg2+ is present in ICF alone, total body mg is about 25g, 60% (15g) of this is complexed with calcium bone. One third (5g) of skeletal mg is exchangeable with serum mg. This metal is the major ICF cations.  Functions of Magnesium Mg is the activator of many enzymes requiring ATP such as Alkaline phosphatase, hexokinase, fructokinase etc. Magnesium is involved in carbohydrate, nucleotide, nucleic acid and amino acid metabolism, protein synthesis and muscle activation. Mg is involved in many biological processes such as hormone receptor binding, gating of calcium channels, transmembrane ionflux , cardiac excitability and neuro- trasmitters release. Mg increases body’s ability to utilize other minerals like calcium, phosphorus, potassium and vitamins C, E & B compound  Functions and Regulation Mg is involved in insulin secretion, binding to receptors and activity, for these reasons, mg deficiency has been implicated in type 2 diabetes Regulation of plasma magnesium Kidney is the primary regulator of body mg balance. Renal mg regulation is essentially a filtration and re-absorption processes. Normal intake of mg is about 300-350 mg per day. About 100 – 150mg/day is excreted through urine, this is equal to the amount absorbed daily. Thus body mg balance is determine by renal excretion of mg  Hypomagnesemia Hypomagnesemia is the condition of mg deficiency, several diseases can cause hypomagnesemia, it occurs in hyperthyrodism, chronic alcoholism, Vomiting diarrhoea, pancreatitis and malabsorption syndrones. The normal serum level of mg is1.7-2.4mg/dl Symptoms include weakness, lethargy, muscle cramps and confusion. Magnesium deficiency and diabetes Mg deficiency are involved in development of insulin resistance, carbohydrate intolerance, accelerated atherosclerosis,  Toxicity hypertension, diabetic neuropathy and cardiovascular, complications. Diabetic patients have low mg levels. It is believed that glycosuria that occurs in diabetic patients impairs renal reabsorption of mg from filtrate. Toxicity- Magnesium overdose leads to hypermagnesemia, it occurs in renal failure and due to excess intake of antacids. Symptoms include muscle weakness, nausea, depression and death may occur due to respiratory paralysis. Major sources – nuts, legumes, pears, whole grains are good sources but fish, meat, green leafy vegetables are fair sources. RDA-300-350mg/day but higher quantity is required during pregnancy and lactation.  POTASSIUM Human body contains about 250mg of K+. Most of it is present inside various cells of the body and the remaining is found in ECF. It is another major cation of ICF. Functions: Potassium is required for maintenance of plasma volume bile salt formation for the activity of Na+/K+- ATPase  Functions cont. glycogen storage in the liver and muscle. About 14mg of potassium is required to store 1g of glycogen. growth of tissues, it plays important role in heart muscular contraction. It plays an important role in nerve & muscle functions Deficiency & Toxicity Normal serum potassium level is 3-5meq/L, nutritional deficiency of k is rare. However, serum k level is decreased (hypokalemia) in many conditions and increased beyond normal level (hyperkalemia) by several diseases. Hypokalemia occurs in vomiting/diarrhea, prolonged use of diuretics used for (cardiac failure) and during treatment with insulin.  Potassium Symptoms include muscular weakness, heart enlargement and paralysis. Hyperkalemia occurs in renal failure and severe dehydration. symptoms are weakness, numbness, Low heart beats and cardiac arrest due to collapse of peripheral vasculature. Sources of K are oil seeds, eggs, meat, vegetables and fruits. RDA is 2.3g/day. Chloride (Cl-) Human body contains about 120 – 150mg of chloride. it is present in the major body fluids, soft tissues and erythrocytes. It is the major extracellular anion in mostcells  Chloride Functions of CL- It is required for the secretion of HCL in gastric juice. Ceribro spinal fluid (CSF) has the highest concentration of chloride in man. It is involved in maintenance of electrical neutrality of erythrocytes (Chloride shift) and other cells. It is also used to maintain plasma volume.  Deficiency & Toxicity Nutritional deficiency is rare. Normal serum CL- level is 95- 105m Eq/L. serum chloride level is found decreased (hypochloramia) and increased (ypercloramia) in some diseases. The excretion of chloride is through urine, and it is parallel to Na+. daily excretion of Cl_ is about 5 – 8g/day. Hypochloremia occurs in prolonged vomitting , diarrhea, pyloric obstruction, cholera, Aids, meningites. Symptoms are muscular spasm. Source – pulses, milk, meat and eggs. Salted foods are excellent sources. Daily requirement (Adults) 1.5 – 3.5gm/day.  Phosphorus (P) Human body contain about 500 – 700g of Phosphorus in the body, P is present as inorganic phosphate complexed with calcium and mg in the bone and teeth. Organic phosphate is associated with phospholipid of cell membranes, nucleic acid and as intracellular anion in cells.  Functions of Phosphorus Functions of phosphate ions It is an important constituent of blood buffer. It is a constituent of high energy compounds like ATP, GTP etc. It is involved in modification and activation of several enzymes and cellular proteins. It is required for the synthesis of nucleoside co-enzymes, such as NAD+ and NADP + Formation of phosphate esters such as glucose 6-po4 It is required for the synthesis of DNA & RNA It is a constituent of secondary messengers like cAMP, cGMP etc  Deficiency and Absorption of PO4 Deficiency The deficiency of P04 occurs due to impaired absorptions and / or excessive loss through the kidney. Factors affecting absorption of phosphate Calcitriol increases the absorption of P04 in the intestine by sodium and glucose dependent mechanism. High calcium diet decreases the absorption of P04 by forming insoluble calcium P04 salt. Antacids interferes with phosphate absorption if taken in excess.  Serum level of phosphate SL of P04 is 3-4mg/dl in normal adults and 5-6 mg/dl in children. Hemolysis should be prevented when blood is taken for phosphate estimation. Usually, the daily requirement is about 200-300mg/day Sources:- milk is a good source, it contains about 100gm/dL of milk. Cereals, nuts, eggs & meats are moderate sources.  TRACE ELEMENTS Zinc Human body contains about 2-3gm of zinc, of this, 60% is present in skeletal muscle and 30% in bones. The remaining is present in body fluids. Among the different organs of the body, prostate alone contains 86mg/100g and choroids of eye are rich in zinc. Functions: Zinc is required for the activity of several enzymes involved in various metabolic pathways e.g Protein, amino acids, nucleic acids and bones.  Functions of zinc Zinc is involved in stabilization of hormone insulin It maintains the structure of chromatin and ribosomes. Zinc is essential for immune system. It is required for normal reproduction. It is required for muscle and bone formation. It is required for basic cellular functions like DNA replication, transcription, cell division and cell activation.  Sources of zinc Deficiency of zinc is rare in man Sources- Sea foods like oysters and herrings are excellent sources, meat, liver and eggs are good sources, cereal, pulses, nuts, Vegetables and milk are fair sources. RDA – 15mg/day, during pregnancy and lactation, 25mg/day.  Copper (Cu) Copper – Human body contains about 100-150mg of copper, of this 40% is in the muscle, 15% in the liver and 10% in the brain. The leftover is present in the body fluids. Absorption of copper takes place in the small intestine. Functions Copper is required for the activity of enzymes involved in respiratory chain, cross linking of collagen and elastin, blood cell formation, melanin formation, super oxides removal, neuro transmitters and neuro –speptides formation. In most of the cases copper is part of enzymes molecules. Some cupro-enzymes are cytochrome oxidase, superoxide dismutase, ceruloplasm, tyrosinase, dopamine beta-oxidase. It increases iron absoption and HDL level, hence protects the heart.  Copper Copper toxicity __Excess copper intake may lead to hemolysis, hemoglobinnuria, protenuria and renal failure. Deficiency- It is rare in adults human but preterm infants may have copper deficiency. Symptoms include anemia, bone demineralization, fragility of large blood vessels and pigmentation of skin. Source: Cereal, milk, eggs, meat, vegetables & fruits RDA – 2.0mg/day  Iodine Human body contains about 15 – 20 mg/day, 80% is in the thyroid gand. Functions It is required for the formation of thyroid harmones They are essential for growth & development Iodine deficiency disorder – (IDD) The most common IDD is goiter ( swollen of thyroid gland on the neck) Decreased Intelligent Quotient (IQ) in children Other IDD are hypo-tyroidism, mental disturbances and iodine induced hyper-tyroidism. Iodine deficient people are more susceptible to radiation effects.  Iodine Goitrogenic factors ID occurs when foods containing goitrogenic substance are consumed. Goitrogenic factors are present in cabbage, cauliflower and raddish. They interfere with iodine uptake by thyroid gland which causes a condition identical to iodine deficiency. Therapentic use Table salt supplemented with iodine prevents goitre and other conditions caused by iodine deficiency. Iodine salts are consumed to prevent accumulation of radioactive iodine in thyroid gland in case of nuclear blasts and accidents. Sources Sea foods like sea fish and shell fish, cereals, milk, meat, egg, vegetable, root vegetables and fruits. RDA-150 microgram/day or 0.15mg/day