2. • Inorganic elements essential to the nutrition of humans
• constitute only a small proportion of the body weight. There is a wide variation
in their body content. For instance, calcium constitutes about 2% of body
weight while cobalt about 0.00004%
• Minerals play an important role in a variety of metabolic reactions as cofactor
• Essential for the very existence of the organism. These include calcification of
bone, blood coagulation, neuromuscular irritability, acid-base equilibrium, fluid
balance and osmotic regulation
Mineral Balance
• Body maintains tight control over mineral balance
• Gastro Intestinal tract Regulates absorption from food, based on the body’s
need
• Minerals in gastric juices and intestinal cells are either excreted in the feces or
reabsorbed through the large intestine
• Kidneys: Excretes excess and reabsorbs the minerals when the body needs them
3. • Major minerals
• The seven principal elements (macro minerals) constitute 60-80% of the
body's inorganic material.
• Need to consume > 100 milligrams per day
• Calcium, sodium, potassium, chloride, phosphorus, magnesium, and sulfur
• Trace minerals – Need to consume > 20 milligrams per day
• Iron, zinc, copper, selenium, chromium, iodide, manganese, molybdenum,
and fluoride
• Essential trace elements : lron, copper, iodine, manganese/ zinc,
molybdenum, cobalt, fluorine, selenium and chromium
• Possibly essential trace elements : Nickel, vanadium, cadmium and barium
• Non-essential trace elements : Aluminium. lead, mercury, boron, silver,
bismuth
4. Calcium
• Calcium is the most abundant among the minerals in the body. The total
content of calcium in an adult man is about 1 to 1 .5 kg. As much as 99% of
it is present in the bones and teeth.
• A small fraction (1%) calcium, found outside the skeletal tissue, performs a
wide variety of functions
• Development of bones and teeth : Calcium, along with phosphate, is
required for the formation (of hydroxyapatite) and physical strength of
skeletal tissue. Bone is regarded as a mineralized connective tissue.
• Bones which are in a dynamic state serve as reservoir of Ca.
• Muscle contraction : Ca2+ interacts with troponin C to trigger muscle
contraction. Calcium also activates ATPase, increases the interaction
between actin and myosin
5. • Blood coagulation : Several reactions in the cascade of blood clotting
process are dependent on Ca2+ (factor lV).
• Nerve transmission : Ca2+ is necessary for the transmission of nerve
impulse.
• Membrane integrity and permeability : Ca2+ influences the membrane
structure and transport of water and several ions across it
• Activation of enzymes : Ca2+ is needed for the direct activation of enzymes
such as lipase (pancreatic), ATPase and succinate dehydrogenase.
• Calmodulin mediated action of Ca2+ : Calmodulin is a calcium binding
regulatory protein. Ca-calmodulin complex activates certain enzymes e.g.
adenylate cyclase, Ca2+ dependent protein kinases.
• Release of hormones : The release of certain hormones (insulin, PTH,
calcitonin) from the endocrine glands is facilitated by Ca2+.
6. • Calcium as intracellular messenger : Certain hormones exert their
action through the mediation of Ca2+ (instead of cAMP).
• Calcium is regarded as a second messenger for such hormonal action
e.g. epinephrine in liver glycogenolysis.
• Calcium serves as a third messenger for some hormones e.g.
antidiuretic hormone (ADH) acts through cAMP, and then ca2+.
• Factors effecting Calcium absorption
• Vitamin D (through its active form calcitriol) induces the synthesis of
calcium binding protein in the intestinal epithelial cells and promotes
Ca absorption.
• Parathyroid hormone enhances Ca2+ absorption through the increased
synthesis of calcitriol.
• Acidity (low pH) is more favorable for Ca absorption.
7. • Lactose promotes calcium uptake by intestinal cells.
• The amino acids lysine and arginine facilitate Ca absorption.
Factors inhibiting Ca absorption
• Phytates and oxalates form insoluble salts interfere with Ca absorption.
• High content of dietary phosphate results in the formation of insoluble
calcium phosphate and prevents Ca uptake. The dietary ratio of Ca and P-
between 1 : 2 and 2 : 1-is ideal for optimum Ca absorption by intestinal
cells.
• The free fatty acids react with Ca to form insoluble calcium soaps. This is
particularly observed when the fat absorption is impaired.
• Alkaline condition (high pH) is unfavorable for Ca2+ absorption.
• High content of dietary fiber interferes with Ca2+ absorption.
8. DISEASE STATES
• The blood Ca2+ level is maintained within a narrow range by the
homeostatic control, most predominantly by PTH. Hence abnormalities
in Ca metabolism are mainly associated with alterations in PTH.
• Hypercalcemia
• Elevation in serum Ca level (normal 9-11mg/dl) is hypercalcemia.
Hypercalcemia is associated with hyperparathyroidism caused by
increased activity of parathyroid glands. Decrease in serum phosphate
and increase in alkaline phosphatase activity are also found in
hyperparathyroidism. Elevation in the urinary excretion of Ca and P,
often resulting in the formation of urinary calculi, is also observed in
these patients
• The symptoms of hypercalcemia include lethargy, muscle weakness,
loss of appetite, constipation, nausea, increased myocardial
contractility and susceptibility to fractures
9. Hypocalcemia
• Hypocalcemia is a more serious and life threatening condition. lt is
characterized by a fall in the serum Ca to below 7 mg/dl, causing tetany.
The symptoms of tetany include neuromuscular irritability, spasms
( involuntary muscular contraction) and convulsions (Irregular movement
of body).
• Hypocalcemia is mostly due to hypoparathyroidism. This may happen
after an accidental surgical removal of parathyroid glands or due to an
autoimmune diseases
• Rickets is a disorder of defective calcification of bones. This may be due
to a low levels of vitamin D in the body or due to a dietary deficiency of
Ca and P-or both.
10. • Osteoporosis
• Osteoporosis is characterized by demineralization of bone resulting in the
progressive loss of bone mass.
• Osteoporosis results in frequent bone fractures which are a major cause of
disability among the elderly
• Estrogen administration along with calcium supplementation (in
combination with vitamin D) to postmenopausal women reduces the risk
of fractures
Plasma Calcium
• Most of the blood Ca is present in the plasma
• since the blood cells contain very little of it. The normal concentration of plasma or
serum Ca is 9-11 mg/dl. About half of this (5 mg/dl) is in the ionized form which is
functionally the most active . At least 1 mg/dl serum Ca is found in association with
citrate and/or phosphate. About 40% of serum Ca (4-5mg/dl) is bound to proteins,
mostly albumin and, to a lesser extent, globulin.
• Ionized and citrate (or phosphate) bound Ca is diffusible from blood to the tissues while
protein bound Ca is non-diffusible. In the usual laboratory determination of serum Ca,
all the three fractions are measured together.
11. Phosphorus
• Phosphorus is a mineral that makes up 1% of a person's total body weight.
• It is the second most abundant mineral in the body. It is present in every cell of
the body. Most of the phosphorus in the body is found in the bones and teeth
• Meat, fish, poultry, eggs, milk, processed foods
Biochemical functions
• Phosphorus is essential for the development of bones and teeth.
• lt plays a central role for the formation and utilization of high-energy phosphate
compounds e.g. ATP, GTP, creatine phosphate etc.
• Phosphorus is required for the formation of phospholipids, phosphoproteins and
nucleic acids (DNA and RNA).
• lt is an essential component of several nucleotide coenzymes e.g. NAD+, NADP+,
pyridoxal phosphate, ADP and AMP.
• Several proteins and enzymes are activated by phosphorylation.
• Phosphate buffer system is important for the maintenance of pH in the blood
(around 7.4) as well as in the cells.
12. Absorption
• Phosphate absorption occurs from jejunum
• Calcitriol promotes phosphate uptake along with calcium
• Absorption of phosphorus and calcium is optimum when the dietary Ca : P is
between 1:2 and 2:1.
• Acidity favors while phytate decreases phosphate uptake by intestinal cells
Disease states
• Serum phosphate level is increased in hypoparathyroidism and decreased in
hyperparathyroidism.
• ln severe renal diseases/ serum phosphate content is elevated causing acidosis.
• Vitamin D deficient rickets is characterized by decreased serum phosphate
• Renal rickets is associated with low serum phosphate levels and increased alkaline
phosphatase activity.
• In diabetes mellitus, serum content of organic phosphate is lower while that of
inorganic phosphate is higher.
• The organic phosphates are phosphates of esters whereas the inorganic
phosphates are salts of phosphoric acid
13. Serum phosphate
• The phosphate level of the whole blood is around 40 mg/dl while serum
contains about 3-4 mg/dl. This is because the RBC and WBC have very
high content of phosphate.
• The serum phosphate may exist as free ions (40%) or in a complex form
(50%) with cations such as Ca2, Mg2, Na+, K+.
• About 10% of serum phosphate is bound to proteins. lt is interesting to
note that the fasting serum phosphate levels are higher than the
postprandial. This is attributed to the fact that following the ingestion of
carbohydrate (glucose), the phosphate from the serum is drawn by the
cells for metabolism (phosphorylation reactions).
14. Magnesium
Magnesium is an important mineral, playing a role in over 300 enzyme reactions in the
human body.
The adult body contains about 20 g magnesium, 70% of which is found in bones in
combination with calcium and phosphorus. The remaining 30% occurs in the soft tissues
and body fluid
It contributes to the structural development of bone and teeth's
• Mg serves as a cofactor for several enzymes requiring ATP e.g. hexokinase, glucokinase,
phosphofructokinase, adenylate cyclase.
• Mg is necessary for proper neuromuscular function. Low Mg2+ levels lead to
neuromuscular irritability
• Magnesium also plays a role in the active transport of calcium and potassium ions
across cell membranes, a process that is important to nerve impulse conduction,
muscle contraction, and normal heart rhythm
• Magnesium therapy may help prevent or relieve headaches. This is because a
magnesium deficiency can affect neurotransmitters and restrict blood vessel
constriction; People who experience migraines may have lower levels of magnesium in
their blood
15. • Sources: Nuts and seeds; legumes; leafy, green vegetables; seafood; chocolate;
"hard" drinking water
Absorption
• Magnesium is absorbed by the intestinal cells through a specific carrier system.
About 50% of the dietary Mg is normally absorbed. Consumption of large amounts
of calcium, phosphate and alcohol diminishes Mg absorption. PTH increases Mg
absorption.
Serum Mg
• Normal serum concentration of Mg is 2-3 mg/dl. lt is present in the ionized form
(60%), in combination with other ions (10%) and bound to proteins (30%).
Disease states
• Magnesium deficiency causes neuromuscular irritation. weakness and convulsions
• These symptoms are similar to that observed in tetany (Ca deficiency) which are
relieved only by Mg. Malnutrition, alcoholism and cirrhosis of Liver may lead to Mg
deficiency.
• Low levels of Mg may be observed in uremia, rickets and abnormal pregnancy
16. SODIUM
• Most of the sodium of the human body is present in the soft tissues and
body fluids; like potassium it is concerned with the acid base balance and
osmotic regulation
• Much of it is ingested as common salt and excreted in urine
Sodium functions
• lt is necessary for the normal muscle irritability and cell permeability
• Sodium is involved in the intestinal absorption of glucose, galactose and
amino acids
• lt is necessary for initiating and maintaining heart beat
• Sodium shifts into cells and potassium shifts out of the cells (sodium
pump)
17. Sodium-potassium pump (Na+/K+ ATPase)
• The sodium-potassium pump was discovered in the 1950s by a Danish
scientist, Jens Christian Skou, who was awarded a Nobel Prize in 1997.
• Failure of the Na-K pumps can result in swelling of the cell.
• A cell's osmolarity is the sum of the concentrations of the various ion
species and many proteins and other organic compounds inside the cell
When this is higher than the osmolarity outside of the cell, water flows
into the cell through osmosis. This can cause the cell to swell up and lyse
• The Na-K pump helps to maintain the right concentrations of ions
Furthermore, when the cell begins to swell, this automatically activates
the Na-K pump
18. Hyponatremia
• The serum sodium level falls below the normal. Hyponatremia may
occur due to diarrhea, vomiting, chronic renal diseases, adrenocortical
insufficiency (Addison's disease).
• Administration of salt free fluids to patients may also cause
hyponatremia. This is due to overhydration. Decreased serum sodium
concentration is also observed in edema which occurs in cirrhosis or
congestive heart failure.
• The manifestations of hyponatremia include reduced blood pressure and
circulatory failure
19. Hypernatremia
• This condition is characterized by an elevation in the serum sodium level. The
symptoms include increase blood volume and blood pressure.
• lt may occur due to hyperactivity of adrenal cortex (Cushing's syndrome),
prolonged administration of cortisone, ACTH and/or sex hormones. Loss of
water from the body causing dehydration, as it occurs in diabetes insipidus,
results in hypernatremia
• Rapid administration of sodium salts also increases serum sodium
concentration. lt may be noted that in pregnancy, steroid and placental
hormones cause sodium and water retention in the body, leading to edema.
• In edema, along with water, sodium concentration in the body is also
elevated. Administration of diuretic drugs increases the urinary output of
water along with sodium. in the patients of hypertension and congestive
cardiac failure salt (Na+) restriction is advocated
20. POTASSIUM
Biochemical functions
• Potassium functions like sodium, chloride and bicarbonate ions
• Potassium maintains intracellular osmotic pressure.
• lt is required for the regulation of acid base balance and water balance in the
cells.
• The enzyme pyruvate kinase (of glycolysis) is dependent on K+ for optimal
activity.
• Potassium is required for the transmission of nerve impulse.
• Adequate intracellular concentration K+ is necessary for proper biosynthesis of
proteins by ribosomes.
• Extracellular K+ influences cardiac muscle activity.
Sources: Meats, milk, fresh fruits and vegetables, whole grains, legumes
21. Disease states
• Serum potassium concentration is maintained within a narrow range. Either
high or low concentrations are dangerous since potassium effects the
contractility of heart muscle.
• Hypokalemia : Decrease in the concentration of serum potassium is observed
due to overactivity of adrenal cortex (Cushing's syndrome)
• The symptoms of hypokalemia include irritability, muscular weakness,
tachycardia, cardiomegaly and cardiac arrest. Changes in the ECG are observed
(flattened waves with inverted T wave).
• Hyperkalemia : Increase in the concentration of serum potassium is observed
in renal failure, adrenocortical insufficiency (Addison's disease), diabetic
coma, severe dehydration, intravenous administration of fluids with excessive
potassium salts.
• The manifestations of hyperkalemia include depression of central nervous
system, mental confusion, numbness, bradycardia with reduced heart sounds
and, finally, cardiac arrest. Changes in ECG are also observed (elevated T
wave).
22. CHLORIDE
• Chlorine is a constituent of sodium chloride. Hence, the metabolism of
chlorine and sodium are intimately related
• The enzyme salivary amylase is activated by chloride.
• Chloride is principle anion of body fluids.
• It is associated with sodium and potassium in acid-base balance and
osmosis.
• plays an important role in gastric secretion (hydrochloric acid) and digestion.
• It is excreted in urine and in perspiration with sodium and potassium.
Sources: Chloride is part of sodium chloride.
• With exception of fish and meat meals, the chloride contents of most of the
foods is very low.
23. Chloride Functions
• Found in extracellular fluids
• Changes the blood osmolality
• Goes with Na in retention of water
• Chloride combines with hydrogen to form hydrochloric acid in the stomach
• The enzyme salivary amylase is activated by chloride
Disease states
• Hypochloremia : A reduction in the serum Cl- level may occur due to vomiting,
diarrhea, respiratory alkalosis, Addison's disease (adrenal glands do not
produce enough steroid hormones) and excessive sweating.
• Hyperchloremia : An increase in serum Cl- concentration may be due to
dehydration, respiratory acidosis and Cushing's syndrome
( body makes too much of the hormone cortisol over a long period of time)
24. Sulfur
• Sulfur of the body is mostly present in the organic form. Methionine, cysteine and
cystine are the three sulfur-containing amino acids present in the proteins. Generally,
proteins contain about 1% sulfur by weight.
Biochemical functions
• Sulfur-containing amino acids are very essential for the structural conformation and
biological functions of proteins (enzymes, hormones, structural proteins etc.). The
disulfide linkages (-S-S-) and sulfhydryl groups (-SH) are largely responsible for this.
• The vitamins thiamine, biotin, lipoic acid, and coenzyme A of pantothenic acid contain
sulfur.
• Heparin, chondroitin sulfate, glutathione, taurocholic acid are some other important
sulfur containing compounds.
• Phospho adenosine phosphor sulfate (PAPS) is the active sulfate utilized for several
reactions e.g. synthesis of glycosaminoglycans, detoxification mechanism.
• The sulfur-containing amino acid methionine is actively involved in transmethylation
reactions
25. Iron
• The total content of iron in an adult body is 3-5 g.
• About 70% of this occurs in the erythrocytes of blood as a constituent of
hemoglobin.
• At least 5% body iron is present in myoglobin of muscle.
• Heme is the most predominant iron-containing substance.
• lt is a constituent of several proteins/enzymes (hemoproteins, hemoglobin,
myoglobin, cytochromes, xanthine oxidase, catalase, tryptophan, peroxidase
Iron present in Hb is Fe 2+ state
Organic/heme iron (10%) Fe2+ (more soluble).
Inorganic/non-heme iron (90%) Fe3+ (less soluble)
Biochemical Functions
1. Iron mainly exerts its functions through the compounds in which it is present.
Hemoglobin and myoglobin are required for the transport of O2 and CO2.
2. Cytochromes and certain non-heme proteins are necessary for electron transport
chain and oxidative phosphorylation.
26. 3. Peroxidase, the lysosomal enzyme, is required for phagocytosis and
killing of bacteria by neutrophils
4. Iron is associated with effective immunocompetence of the body.
Role of iron in the body
• Iron has three main functions : 1. carrying oxygen from the lungs to
the rest of the body.
• 2. Aiding energy production.
• 3. Iron is constituent of several enzymes including : catalase,
peroxidase, and cytochrome enzymes
27. Iron Absorption and Metabolism
• Free iron is toxic to cells as it acts as a catalyst in the formation of free
radicals. Hence, within cells, iron is stored in a protein complex as ferritin
(major) or hemosiderin.
• – Apoferritin can take up to 4300 atoms of iron per molecule.
• – Blood transferrin: transfers the iron to the rest of the body. Transferrin
receptors are present on most body cells, especially on cells which synthesize
heme.
Absorption-Enhancing Factors:
• MFP factor: a factor associated with the digestion of Meat, Fish, and Poultry
that enhances nonheme iron absorption.
• Vitamin C (ascorbic acid). Ascorbate increases absorption
• Citric acid and lactic acid from foods and HCl acid from stomach
• Sugars
28. Absorption-Inhibiting Factors:
1. Phytate and fibers (grains and vegetables).
2. Oxalates (spinach).
3. Calcium and phosphorus (milk).
4. EDTA Ethylenediaminetetraacetic acid (food additive).
5. Tannic acid (and other polyphenols in tea and coffee).
Iron Absorption from Food
People absorb more iron from foods and supplements when body stores
of iron are low than when stores of iron are high. Macrophages engulfs
old RBCs and releases heme. Heme oxygenase separates them and Fe is
then stored as ferritin.
Iron Deficiency Anemia Normal Red Blood Cells Iron Deficiency Anemia-
Small microcytic and pale hypochromic cells contain less hemoglobin
29. Absorption, transport and storage
• lron is mainly absorbed in the stomach and duodenum. ln normal
people, about 10% of dietary iron is usually absorbed. However, in iron
deficient (anemic) individuals and growing children, a much higher
proportion of dietary iron is absorbed to meet the increased body
demands.
• lron is mostly found in the foods in ferric form (Fe3+), bound to
proteins or organic acids. In the acid medium provided by gastric HCl,
the Fe3+ is released from foods. Reducing substances such as ascorbic
acid (vitamin C) and cysteine convert ferric iron (Fe3+) to ferrous form
(Fe2+). lron in the ferrous form is soluble and readily absorbed.
30. Iron is a one way substance
• lron metabolism is unique as it operates in a closed system. lt is very
efficiently utilized and reutilized by the body.
• Further, iron losses from the body are minimal (< 1 mg/day) which may
occur through bile, sweat, hair loss etc.
• lron is not excreted into urine. Thus, iron differs from the vitamins or other
organic and inorganic substances which are either inactivated or excreted
during the course of metabolic function. Hence, iron is appropriately
regarded as a one-way substance.
• lron entry into the body is controlled at the absorption level, depending on
the body needs. Thus the periodical blood loss in menstruatiot women
increases its requirements. Increased iron demands are also observed in
pregnancy, lactation, and in growing children.
31. Disease state
lron deficiency anemia : Several factors may contribute to iron deficiency
anemia. These include inadequate intake or defective absorption of iron,
chronic blood loss and repeated pregnancies
Strict vegetarians are more prone for iron deficiency anemia. This is due
to the presence of inhibitors of iron absorption in the vegetarian foods,
besides the relatively low content of iron
Hemosiderosis:
This is a less common disorder and is due to excessive iron in the body. It
is commonly observed in subjects receiving repeated blood transfusions
over the years, e.g. patients of hemolytic anemia, hemophilia. As already
stated, iron is a one-way compound, once it enters the body, it cannot
escape. Excessive iron is deposited as ferritin and hemosiderosis
32. • Hemochromatosis : This is a rare disease in which iron is directly
deposited in the tissues (liver, spleen, pancreas and skin).
Hemosiderosis is sometimes accompanied by hemochromatosis.
Bronzed-pigmentation of the skin, cirrhosis of liver, pancreatic fibrosis
are the manifestations of this disorder. Hemochromatosis causes a
condition known as bronze diabetes
33. Zinc
• Red meat Oysters poultry dairy products
• Zinc functions
• It helps with the human immune system, DNA synthesis, and cells.
• It plays a vital role in growth and developmental functions in pregnant woman,
children and adolescents.
• It is required for proper sense of taste and smell.
• Essential for proper reproduction in males, requires for spermatogenesis
Growth and Development of Immune System, DNA Synthesis
• Zinc deficiency
• Deficiency in Zinc may cause :
• Growth retardation – loss of appetite – impairment of immune functions – hair
loss – Low sperm count
34. Fluorine
• Fluorine prevents tooth decay and cavities and strengths the enamel. •
If there is a deficiency of fluorine during the growing period, it will result
in dental caries and tooth decay.
• Discoloration and pitting of tooth enamel caused by excess fluoride
during tooth development
Copper
• 1. Enzymes catalyze the oxidation of ferrous iron to ferric iron are
copper enzyme
• 2. Helps in the absorption of iron and Synthesis of hemoglobin.
• 3. Superoxide dismutase is Cu enzyme that catalyze the hydrolysis of
superoxide (O2−) into O2 and H2O
35. Iodine
• Food Source : seaweed, shrimp, and other seafood, which are generally rich in iodine.
Iodized Salt
• Absorption : Upper small intestine
• Transport : Binding loosely to plasma proteins
• Storage : 80% in thyroid gland
• Excretion : 2/3rd in urine
• Required for the synthesis of thyroid hormones T4 and T3
• Chemistry of Thyroid hormones • Thyroid hormones are derivatives of the amino acid
tyrosine bound covalently to iodine.
• Goiter: The most common cause of goiters worldwide is a lack of iodine in the diet.
goiter is more often due to the over- or underproduction of thyroid hormones or to
nodules in the gland itself.
• It may activate certain enzymes related to glucose metabolism.
• It aid in prolactin production, and thus be involved in human breast milk production.
36. Manganese:
1 . Mn serves as a cofactor for several enzymes. These include arginase,
pyruvate carboxylase, isocitrate dehydrogenase, superoxide dismutase
(mitochondrial) and peptidase.
2. Mn is required for the formation of bone, proper reproduction and
normal functioning of nervous system.
3. Mn is necessary for the synthesis of mucopolysaccharides and
glycoproteins.
4. Hemoglobin synthesis involves Mn.
5. Mn inhibits lipid peroxidation.
6. Mn is necessary for cholesterol biosynthesis
Widespread in foods, especially plant foods
37. Selenium
1. Selenium, along with vitamin E, prevents the development of hepatic necrosis and
muscular dystrophy
2. Se is involved in maintaining structural integrity of biological membranes.
3. Se as selenocysteine is an essential component of the enzyme glutathione
peroxidase. This enzyme protects the cells against the damage caused by H2O2. lt
appears from recent studies that selenocysteine is directly incorporated during
protein biosynthesis. Therefore, selenocysteine is considered as a separate (21st)
amino acid.
4. Se prevents lipid peroxidation and protects the cells against the free radicals,
including superoxide.
5. Se protects animals from carcinogenic chemicals. However, the precise role of Se in
humans with regard to cancer prevention is not clearly identified.
6. Se binds with certain heavy metals (Hg, Cd) and protects the body from their toxic
effects.
7. A selenium containing enzyme S'-deiodinase converts thyroxine (T4) to
triiodothyronine in the thyroid gland.
8. Thioredoxin reductase, involved in purine nucleotide metabolism, is also a seleno
protein
38. Chromium
• The total human body contains about 6 mg chromium. The Cr content of blood is
about 20 mg/dl. Cr performs several biochemical functions.
• 1. In association with insulin, Cr promotes the utilization of glucose. Cr is a
component of a protein namely chromodulin which facilitates the binding of
insulin to cell receptor sites.
• 2. Cr lowers the total serum cholesterol level.
• 3. lt is involved in lipoprotein metabolism. Cr decreases serum low density
lipoproteins (LDL) and increases high density lipoproteins (HDL) and, thus,
promotes health.
• 4. lt is believed that Cr participates in the transport of amino acids into the cells
(heart and liver).
• The dietary requirement of Cr is not known. lt is estimated that an adult man
consumes about 10 to 100 mg/day. The good sources of Cr include brewer's yeast,
grains/ cereals/ cheese and meat.
• Chromium deficiency causes disturbances in carbohydrate, lipid and protein
metabolisms. Excessive intake of Cr results in toxicity, leading to liver and kidney
damage.
