Minerals are essential for the normal growth and maintenance of the body. If the daily requirement is more than 100 mg / day, they are called major elements and if the daily requirements is less than 100 mg / day, they are called minor elements. The role of minerals and vitamins in maintaining homeostatic balance and mediating metabolism in the skeleton, tissue, body fluids, digestive juices, etc.
Total calcium in the human body is 1 to 1.5kg, out of which 99 percent is seen in bone and 1 percent in extracellular fluid.Milk is the main source of calcium but other sources includes green leafy vegetables such as broccoli, cabbage and okra, but not spinach.Soya beans,cereal,tofu,fish when eating the bone.The daily calcium requirement for children is 1200 mg / day and 500 mg / day for adults.During pregnancy / lactation,the calcium requirement is 1500 mg / day.
Calcium absorption takes place in the first and second parts of duodenum. Calcium absorption requires carrier protein assisted by Ca2 +–ATpase dependent.
Vitamin D is responsible for increasing the absorption of calcium Hormones, acidity and amino acids of parathyroid. Factors like phytic acid, oxalates, syndromes of malabsorption and phosphates reduce the absorption of calcium. That’s the The normal blood calcium level is 9 -11 mg / dl.
What are the function of Calcium
The following are Calcium ‘s main functions
- Calcium is necessary for transmission of nerve impulse from presynaptic to postsynaptic region.
- Excitation and contraction of muscle fibres needs calcium. The active transport system utilizing calcium binding protein is called Calsequestrin. Calcium decreases neuromuscular irritability.
- Calcium is the second messenger of protein and inositol triphosphate system.
- The Secretion of insulin, parathyroid hormone, calcium etc, from the cells requires calcium
- For coagulation factors such as prothrombin, calcium is also necessary
- Calcium prolongs systole
- The Bones and tooth contains bulk quantity of calcium
What are the factors regulating blood calcium level
The factors regulating the level of blood calcium includes :
|Vitamin D and absorption of calcium:||Calcium ‘s active form is calcitriol. Calcitriol enters the intestinal wall and binds to the cytoplasmic receptor and binds to DNA causing depression and consequent transcription of calbindin gene code. Because of increased calbindin availability, calcium absorption increases leading to increases|
|Vitamin D and Bone||Vitamin D activates osteoblasts, cells that form bones and stimulates Alkaline phosphatase secretion. Because of the enzyme, calcium and Increase phosphorus.|
|Vitamin D and Kidney||Calcitriol increases calcium and phosphorus reabsorption through the renal tubules.|
Parathyroid hormone (PTH)
The normal serum PTH level is 10-60 ng / l.
|PTH and bones||PTH causes demineralization in bone. It also leads to recreation Osteoclastic collagenase causes loss of matrix and resorption of the bone. In the urine, mucopolysaccharides and hydroxyproline are therefore excreted.|
|PTH and Kidney||In the kidney, PTH causes increased calcium reabsorption but decreases phosphorus reabsorption from the kidney tubules.|
Calcitonin decreases the level of serum calcium. It inhibits bone resorption. Decreases osteoclastic activity and increases osteoblasts.
When the Ca2 + plasma level exceeds 11 mg / dl,it is called hypercalcemia. It should be Parathyroid adenoma or tumor secretion of ectopic PTH. In this situation, Calcium excreted in urine decreases the excretion of hyperchloremic chloride Acidosis. Acidosis. Hyperchloremic acidosis symptoms are the following:
- Polyuria, polydipsia
- Confusion, depression, psychosis
- Renal stones
Calcium plasma level below 8 mg / dl is called hypocalcemia.Tetany because of accidental surgical removal or autoimmune disease of the parathyroid glands.In tetany, neuromuscular irritability is increased.Increased internal Q-7 in the ECG is also seen. Main manifestation is carpopedal spasm. Laryngismus and stridor are also observed. Laryngeal spasm may lead is death. The causes of laryngeal spasm includes
- Deficiency of vitamin D
- Deficiency of parathyroid
- Increased calcitonin
- Deficiency of calcium intake
The total body phosphorus content is 1 kg. Bone has 80% of the total phosphorus and the muscle contains 10 percent. The body needs 500 mg Phosphorus per day. Milk is a good source of phosphorus and contains approximately 100 mg / dl. Besides milk, cereals, nuts and meat are also sources of phosphorus.Serum phosphate level is 3 – 4 mg / dl in adults and 5 – 6 mg / dl in children. Calcitriol consumption increases phosphate absorption.
What are the functions of phosphorus
- plays a key role in tooth and bone formation
- Formation of phosphodiester backbone structure for synthesis of DNA and RNA
- Production of high – energy compounds such as ATP, CTP, GTP, etc.
- Synthesis of nucleotide coenzymes such as NAD and NADP
Hypophosphatemia is the condition that leads to a reduction in absorption of Phosphorus. In addition, it leads to hypercalcemia, chronic alcoholism and urinary phosphate excretion.In hyperphosphatemia, increase Phosphate absorption has been noticed.Hyperphosphatemia leads to lysis of cells,Thyrotoxicosis and hypocalcemia.
Optimum magnesium levels for human consumption range from 300 to 400 mg per day. Magnesium ‘s most important source is cereals, beans, leafy vegetables and Fish.The normal Magnesium serum level is 1.8 to 2.2 mg / dl.
What are the functions of Magnesium
- Magnesium reduces the irritability of neuromuscular tissues
- Magnesium deficiency leads to a reduction in insulin dependent glucose absorption
- Magnesium supplementation improves glucose tolerance
Decreasing in magnesium content leads to hypomagnesemia. It causes an increase in urinary loss.Causes such as cirrhosis of the liver, malnutrition of protein calories and hypothyroidism lead to hypomagnesemia.Increasing magnesium levels is referred to as hypermagnesemia.Renal failure, hyperthyroidism, rickets, oxalate poisoning and multiple myeloma are the main causes of hypermagnesemia.
The total body content of iron is between 3 and 5 gm, 75% of which is found in the blood.The rest in the liver, spleen, bone marrow and muscle.Normal iron consumption limit for adults is 20 mg per day, 20 – 30 mg per day for pregnant women and 40 mg / day for children.Jaggery is Iron’s main source.Other sources of iron include leafy vegetables and meat, and so on.Meat is considered a poor iron source.
Factors influencing iron absorption
Iron is absorbed by the upper part of the duodenum and these various factors affect its absorption.
- Only reduced form (ferrous) of iron is absorbed and ferric form is not absorbed
- Interference substances like phytic acid and oxalic acid reduces iron absorption
- Ascorbic acid (Vitamin C) increases iron absorption
How is Iron absorption regulated
Iron absorption is regulated by three major mechanisms, which includes :
- Mucosal Regulation
- Storer regulation
- Erythropoietic regulation
The absorption of iron in mucosal regulation requires DM-1 and ferroportin.Both the proteins are regulated down by liver-secreted hepcidin.The above regulation occurs when reserves of body iron are adequate.When the body iron content gets felled, storer regulation takes place. In storer regulation the mucosal is signaled for increase in iron absorption. The erythropoietic regulation occurs in response to anemia. Here the erythroid cells will signal the mucosa to increase the iron absorption.
Iron transport in blood
Transferrin is the form of transport of iron in the blood. Transferrin are glycoprotein which are secreted by the liver.Ceruloplasmin is the ferroxidase which oxidizes ferrous to ferric state in the blood
Apo-Transferrin + 2Fe2+ ⎯⎯→ Transferrin combined with 2Fe3+
The storage form of iron is ferritin. Almost no iron is excreted through urine. Feces contains iron as well as iron trapped in the intestine cells.
Anemia is the most common nutritional deficiency disease.The microscopic appearance of anemia is characterized by microcytic hypochromic anemia.Iron toxicity or excess of iron is called as hemosiderosis.Iron toxicity occurs due to repeated blood transfusion.The abnormal gene responsible for hemosiderosis is located on the short arm of chromosome No.6.The main causes of iron deficiency or anemia are
- Nutritional deficiency of iron
- Lack of iron absorption
- Hookworm infection
- Repeated pregnancy
- Chronic blood loss
- Lead poisoning
The whole human body contains approximately 100 mg copper and is found in Muscle, liver, bone marrow, brain, kidney, heart, hair.Enzymes like Cytochrome Oxidase, tyrosinase, lysyl oxidase, alanine synthase, monoamine oxidase, superoxide dismutase and phenol oxidase contains copper.Human normal copper limit is 1.5 to 3 mg / day. sources are cereals, meat, liver, nuts and green leafy vegetables are the main sources of copper. Only 10% of the total dietary copper is absorbed. Copper is mainly excreted through bile and normal serum copper level is 25 to 50 mg / dl.
What are the functions of copper
- Copper is necessary for iron absorption and incorporation of iron into hemoglobin.
- It is very essential for tyrosinase activity
- It is the cofactor for vitamin C requiring hydroxylation
- Copper increases the level of high density lipoprotein and protects the heart
Abnormal metabolism of copper
The abnormal metabolism of copper leads to Wilson’s disease and Menke’s kidney hair syndrome.
Defect in a gene encoding copper binding ATPase of liver cells leads to Wilson’s disease. Wilson’s disease leads to
- Accumulation of copper in liver leads to hepatocellular degeneration and cirrhosis
- Copper deposition in the brain basal ganglia causes lenticular degeneration
- Copper deposits as green pigmented ring around cornea and the condition is called as Kayser-Fleischer ring
Over-accumulation of copper can be treated by low-copper diet and D-penicillamine injection, which excretes copper through urine.
Menke’s kidney hair syndrome
It’s an X-links defect. Copper is absorbed by the GI tract in this condition, but it can not be transported to blood. The defect in copper’s blood transport is due to an absence of ATPase binding intracellular copper due to mutation in the gene encoding them.
Zinc daily requirement for human consumption is 10 mg daily. The main sources of Zinc includes grains, beans, nuts, meat and shellfish. In humans, the normal zinc serum level is 100 mg / day.The total human body zinc content is 2gm, 60 percent of which is found in skeletal muscle and 30% in bones with the highest concentration in the hippocampus area of the brain and prostate secretion.
More than 300 enzymes in the human body depend on zinc, some of which are carboxypeptidase, carbonic anhydrase, alkaline phosphatase, lactate dehydrogenase, alcohol dehydrogenase. The RNA polymerase enzyme which is necessary for transcription, contains zinc and is essential for protein biosynthesis.
Deficiency in zinc leads to poor wound healing, impaired skin lesions,spermatogenesis, hyperkeratosis, alopecia and dermatitis. Consumption of more than 1000 mg per day leads to zinc toxicity. Zinc toxicity causes gastric ulcer, Anemia, pancreatitis, nausea and vomiting.
Fluoride is known for its effects on caries. The safe limit of Fluorine in water is about 1 PPM. However, excess fluoride causes Fluorosis which is more dangerous than caries.If the fluoride content exceeds 2 PPM, it causes chronic intestinal disturbance, gastroenteritis, weight loss, osteosclerosis, stratification and tooth discoloration.Fluorose is common in Punjab, Rajasthan, Delhi and Tamilnadu in India.Rich sources of fluoride includes sea fish, cheese, tea and jowar.
Fluorosis could be prevented by supplying and consuming fluoride-free water, additional vitamin c supplementation and the use of fluoride-containing toothpaste could prevent fluorosis.
The normal limit of Selenium for human consumption range from 50 – 100 mg per day and the normal Selenium serum level is from 50 – 100 mg per day. Selenium dependent enzymes include glutathione peroxidase and 5 deiodinase. The highest concentration of selenium in human is found in the testes.It is very important for the normal development and maturation of sperm.
Selenium toxicity can be term Selenosis. Symptoms of Selenosis include Loss of hair, falling of nails, diarrhea, loss of weight and garlicky odor in breath.
The normal limit of Manganese is 5mg / day for humans. The major sources of Manganese are nuts. Its absorption in metabolism is inhibited by iron. In blood, It binds to transmanganine and is excreted through bile.