Trace ElementsTrace Elements

Dr. Nasim IlyasDr. Nasim Ilyas

PGT BiochemistryPGT Biochemistry

Zinc Zinc

Zinc is an essential trace element, necessary for plants, animals, and microorganisms.

Zinc is found in nearly 100 specific enzymes.

ZincZinc

Serves as part of transcription factors.

In proteins, Zn ions are often found in combination with the amino acid such as aspartic acid, glutamic acid, cysteine and histidine.

ZincZinc

2–4 grams of zinc distributed 2–4 grams of zinc distributed throughout the human body. throughout the human body.

Most zinc is in the brain, muscle, Most zinc is in the brain, muscle, bones, kidney, and liver.bones, kidney, and liver.

Highest concentrations in the Highest concentrations in the prostate, parts of the eye and Semenprostate, parts of the eye and Semen

ZincZinc

Has roles in the metabolism of RNA Has roles in the metabolism of RNA and DNA, signal transduction, and and DNA, signal transduction, and gene expression. gene expression.

It also regulates apoptosis. It also regulates apoptosis.

ZincZinc

In the brain, zinc is stored in specific In the brain, zinc is stored in specific synaptic vesicles.synaptic vesicles.

In learning. In learning.

ZincZinc

Zinc-containing enzymes Zinc-containing enzymes Carbonic anhydrase Carbonic anhydrase Carboxypeptidase'sCarboxypeptidase's

ZincZinc

In blood plasma, zinc is bound to In blood plasma, zinc is bound to and transported by albumin (60%, and transported by albumin (60%, low-affinity) and transferrin (10%). low-affinity) and transferrin (10%).

Since transferrin also transports Since transferrin also transports iron, excessive iron reduces zinc iron, excessive iron reduces zinc absorption, and vice-versa. absorption, and vice-versa.

A similar reaction occurs with A similar reaction occurs with copper. copper.

ZincZinc

The concentration of zinc in blood The concentration of zinc in blood plasma stays relatively constant plasma stays relatively constant regardless of zinc intake. regardless of zinc intake.

Cells in the salivary gland, Cells in the salivary gland, prostate, immune system and prostate, immune system and intestine use zinc signaling as one intestine use zinc signaling as one way to communicate with other way to communicate with other cells.cells.

ZincZinc

However, inadequate or excessive However, inadequate or excessive zinc intake can be harmful; zinc intake can be harmful;

Excess zinc particularly impairs Excess zinc particularly impairs copper absorption because copper absorption because metallothionein absorbs both metals. metallothionein absorbs both metals.

Dietary SourcesDietary Sources

Zinc deficiencyZinc deficiency

Zinc deficiency is usually due to:Zinc deficiency is usually due to: Insufficient dietary intake,Insufficient dietary intake, MalabsorptionMalabsorption Chronic liver diseaseChronic liver disease Chronic renal diseaseChronic renal disease Sickle cell diseaseSickle cell disease DiabetesDiabetes MalignancyMalignancy

Zinc deficiencyZinc deficiency

Groups at risk for zinc deficiency Groups at risk for zinc deficiency include the elderly, vegetarians, and include the elderly, vegetarians, and those with renal insufficiency. those with renal insufficiency.

Magnesium Magnesium

Over 300 enzymes require the Over 300 enzymes require the presence of magnesium ions for presence of magnesium ions for their catalytic action.their catalytic action.

Dietary SourcesDietary Sources

MagnesiumMagnesium

Adult human bodies contain about Adult human bodies contain about 24 grams of magnesium:24 grams of magnesium: with 60% in the skeletonwith 60% in the skeleton 39% intracellular (20% in skeletal 39% intracellular (20% in skeletal

muscle)muscle) 1% extracellular. 1% extracellular.

MagnesiumMagnesium

Magnesium is absorbed in the Magnesium is absorbed in the gastrointestinal tract, with more gastrointestinal tract, with more absorbed when body stores is lower. absorbed when body stores is lower.

In humans, magnesium appears to In humans, magnesium appears to facilitate calcium absorption. facilitate calcium absorption.

Low and high protein intake inhibit Low and high protein intake inhibit magnesium absorption.magnesium absorption.

MagnesiumMagnesium

Spices, nuts, cereals, coffee and Spices, nuts, cereals, coffee and vegetables are rich sources of vegetables are rich sources of magnesium. magnesium.

Green leafy vegetables such as Green leafy vegetables such as spinach are also rich in magnesium.spinach are also rich in magnesium.

Manganese Manganese

Manganese is an essential trace Manganese is an essential trace nutrient in all forms of life. nutrient in all forms of life.

The classes of enzymes that have The classes of enzymes that have manganese cofactors are very broad manganese cofactors are very broad and include oxidoreductases, and include oxidoreductases, transferases, hydrolases, lyases, transferases, hydrolases, lyases, isomerases and ligases.isomerases and ligases.

ManganeseManganese

The reverse transcriptases of many The reverse transcriptases of many retroviruses contain manganese. retroviruses contain manganese.

The best known manganese-The best known manganese-containing polypeptides may be containing polypeptides may be arginase, the diphtheria toxin, and arginase, the diphtheria toxin, and Mn-containing superoxide dismutase Mn-containing superoxide dismutase (Mn-SOD).(Mn-SOD).

ManganeseManganese

The human body contains about 10 The human body contains about 10 mg of manganese, mg of manganese, which is stored mainly in the liver and which is stored mainly in the liver and

kidneys. kidneys. In the human brain the manganese In the human brain the manganese

is bound to manganese is bound to manganese metalloproteins most notably metalloproteins most notably glutamine synthetase in astrocytes.glutamine synthetase in astrocytes.

Selenium Selenium

The substance loosely called selenium The substance loosely called selenium sulfide (approximate formula SeS2) is the sulfide (approximate formula SeS2) is the active ingredient in some anti-dandruff active ingredient in some anti-dandruff shampoos. shampoos.

Selenium is used widely in vitamin Selenium is used widely in vitamin preparations and other dietary preparations and other dietary supplements, in small doses supplements, in small doses

(Typically 50 to 200 micrograms per day (Typically 50 to 200 micrograms per day for adult humans).for adult humans).

Iodine Iodine

Iodine's is a constituent of the Iodine's is a constituent of the thyroid hormones: thyroxine (T4) thyroid hormones: thyroxine (T4) and triiodothyronine (T3).and triiodothyronine (T3).

Iodine has a nutritional relationship Iodine has a nutritional relationship with selenium. with selenium.

A group of selenium-dependent A group of selenium-dependent enzymes called deiodinases converts enzymes called deiodinases converts T4(Inactive hormone) to T3 (active T4(Inactive hormone) to T3 (active hormone) by removing an iodine hormone) by removing an iodine atom from the outer tyrosine ring. atom from the outer tyrosine ring.

IodineIodine

Iodine accounts for 65% of the Iodine accounts for 65% of the molecular weight of T4 and 59% of molecular weight of T4 and 59% of the T3. the T3.

15–20 mg of iodine is concentrated 15–20 mg of iodine is concentrated in thyroid tissue and hormones, but in thyroid tissue and hormones, but 70% of the body's iodine is 70% of the body's iodine is distributed in other tissuesdistributed in other tissues

IodineIodine

The daily Dietary Reference Intake The daily Dietary Reference Intake recommended is:recommended is: Between 110 and 130 µg for infants Between 110 and 130 µg for infants 90 - 130 µg for children 90 - 130 µg for children 150 µg for adults150 µg for adults 220 µg for pregnant women220 µg for pregnant women 290 µg. for lactating mothers290 µg. for lactating mothers

IodineIodine

Natural sources of iodine include Natural sources of iodine include seafood, as well as plants grown on seafood, as well as plants grown on iodine-rich soil. iodine-rich soil.

Iodized salt is fortified with iodine.Iodized salt is fortified with iodine.

Iodine deficiencyIodine deficiency

In areas where there is little iodine In areas where there is little iodine in the diet, such as hilly areas.in the diet, such as hilly areas.

Iodine deficiencyIodine deficiency

Iodine deficiency is the leading cause Iodine deficiency is the leading cause of preventable mental retardation. of preventable mental retardation.

Other possible health effects being Other possible health effects being investigated as being related to investigated as being related to deficiency include:deficiency include: Breast cancer. Breast cancer. Stomach cancerStomach cancer

Dietary SourcesDietary Sources

Dietary SourcesDietary Sources

Rich sources of copper include beef Rich sources of copper include beef or lamb liver, nuts, green olive. or lamb liver, nuts, green olive.

Copper Copper

The human body normally contains The human body normally contains copper at a level of about 1.4 to 2.1 copper at a level of about 1.4 to 2.1 mg for each kg of body weight. mg for each kg of body weight.

Copper is distributed widely in the Copper is distributed widely in the body and occurs in liver, muscle and body and occurs in liver, muscle and bone. bone.

Copper is transported in the Copper is transported in the bloodstream on a plasma protein bloodstream on a plasma protein called ceruloplasmin. called ceruloplasmin.

CopperCopper

When copper is first absorbed in the When copper is first absorbed in the gut it is transported to the liver gut it is transported to the liver bound to albumin. bound to albumin.

Copper metabolism and excretion is Copper metabolism and excretion is controlled delivery of copper to the controlled delivery of copper to the liver by ceruloplasmin, where it is liver by ceruloplasmin, where it is excreted in bile.excreted in bile.

CopperCopper

RDA for copper in normal healthy RDA for copper in normal healthy adults is 0.9 mg/day. adults is 0.9 mg/day.

Copper deficiency can often produce Copper deficiency can often produce anemia-like symptoms. anemia-like symptoms.

Conversely, an accumulation of Conversely, an accumulation of copper in body tissues are believed copper in body tissues are believed to cause the symptoms of Wilson's to cause the symptoms of Wilson's disease in humans. disease in humans.

IronIron

Iron is an absolute requirement for Iron is an absolute requirement for most forms of life.most forms of life.

Iron can also be potentially toxic. Iron can also be potentially toxic. It can catalyze the conversion of It can catalyze the conversion of

hydrogen peroxide into free radicals. hydrogen peroxide into free radicals.

The most important group of iron-The most important group of iron-binding proteins contain the heme binding proteins contain the heme molecules, all of which contain iron molecules, all of which contain iron at their centers. at their centers.

The iron-sulfur proteins are another The iron-sulfur proteins are another important group of iron-containing important group of iron-containing proteins. proteins.

Humans also use iron in the Humans also use iron in the hemoglobin of red blood cellshemoglobin of red blood cells

Iron is also an essential component Iron is also an essential component of myoglobin to store and diffuse of myoglobin to store and diffuse oxygen in muscle cells.oxygen in muscle cells.

The human body needs iron for The human body needs iron for oxygen transport oxygen transport

A proper iron metabolism protects A proper iron metabolism protects against bacterial infection. against bacterial infection.

Disease-causing bacteria have Disease-causing bacteria have releasing iron-binding molecules releasing iron-binding molecules called siderophores and then called siderophores and then reabsorbing them to recover iron. reabsorbing them to recover iron.

Most well-nourished people 4-5 Most well-nourished people 4-5 grams of iron in their bodies. grams of iron in their bodies.

Of this, about 2.5 g is contained in Of this, about 2.5 g is contained in the hemoglobin needed to carry the hemoglobin needed to carry oxygen through the blood. oxygen through the blood.

Another 400 mg is devoted to Another 400 mg is devoted to cellular proteins that use iron for cellular proteins that use iron for important cellular processes like important cellular processes like storing oxygen (myoglobin), or storing oxygen (myoglobin), or performing energy-producing redox performing energy-producing redox reactions reactions

3-4 mg circulates through the 3-4 mg circulates through the plasma, bound to transferrin.plasma, bound to transferrin.

Most stored iron is bound by ferritin Most stored iron is bound by ferritin molecules; the largest amount of molecules; the largest amount of ferritin-bound iron is found in cells ferritin-bound iron is found in cells of the liver hepatocytes, the bone of the liver hepatocytes, the bone marrow and the spleen. marrow and the spleen.

The total amount of loss for healthy The total amount of loss for healthy people is estimated average of 1 mg people is estimated average of 1 mg a day for men and 1.5–2 mg a day a day for men and 1.5–2 mg a day for women. for women.

Absorbed in the duodenum by Absorbed in the duodenum by enterocytes of the duodenal lining.enterocytes of the duodenal lining.

To be absorbed, dietary iron can be To be absorbed, dietary iron can be absorbed as part of a protein such as absorbed as part of a protein such as heme protein or must be in its ferrous heme protein or must be in its ferrous Fe2+ form. Fe2+ form.

A ferric reductase enzyme on the A ferric reductase enzyme on the enterocytes' brush border, reduces ferric enterocytes' brush border, reduces ferric Fe3+ to Fe2+. Fe3+ to Fe2+.

These intestinal lining cells can then These intestinal lining cells can then either store the iron as ferritin. either store the iron as ferritin.

Increased demand for iron, which Increased demand for iron, which the diet cannot accommodate.the diet cannot accommodate.

Increased loss of iron (usually Increased loss of iron (usually through loss of blood).through loss of blood).

Nutritional deficiency. This can Nutritional deficiency. This can result due to a lack of dietary iron or result due to a lack of dietary iron or consumption of foods that inhibit consumption of foods that inhibit iron absorption, including calcium iron absorption, including calcium

When When bodybody levels of iron are too low, levels of iron are too low, then hepcidin in the duodenal then hepcidin in the duodenal epithelium is decreased. This causes epithelium is decreased. This causes an increase in ferroportin activity, an increase in ferroportin activity, stimulating iron uptake in the stimulating iron uptake in the digestive system. The reverse occurs digestive system. The reverse occurs when there is an iron surplus.when there is an iron surplus.