Minerals

Dr. Arvind Kumar

Introduction

  • Minerals are inorganic elements required by the human body for normal growth, development, and maintenance of physiological functions.

  • Unlike carbohydrates, proteins, and fats, minerals do not provide energy, but they are essential for structural, regulatory, and metabolic activities.

  • Minerals are obtained from the diet, as the human body cannot synthesize them.

  • They are present in the body in free ionic form or as components of bones, teeth, enzymes, hormones, and body fluids.

  • Minerals play a vital role in:

    • Formation of bones and teeth

    • Maintenance of fluid and electrolyte balance

    • Nerve conduction and muscle contraction

    • Enzyme activation and metabolism

    • Regulation of acid–base balance

  • Based on the amount required by the body, minerals are classified into:

    • Macrominerals (major minerals) – required in amounts >100 mg/day

    • Microminerals (trace elements) – required in amounts <100 mg/day

  • Macrominerals constitute 60–80% of the body’s inorganic content, while trace elements, though required in small amounts, are equally essential for life.

  • Minerals act as structural components (calcium, phosphorus), electrolytes (sodium, potassium, chloride), and enzyme cofactors (iron, zinc, copper, manganese).

  • Both deficiency and excess of minerals can lead to serious metabolic and clinical disorders.

General Functions of Minerals

1. Structural Functions

  • Minerals such as calcium, phosphorus, and magnesium are major components of bones and teeth.

  • They provide rigidity, strength, and structural integrity to the skeletal system.

  • Calcium phosphate in the form of hydroxyapatite is responsible for bone hardness.

2. Maintenance of Fluid and Electrolyte Balance

  • Sodium, potassium, and chloride regulate osmotic pressure and acid–base balance.

  • These minerals help maintain intracellular and extracellular fluid distribution.

  • Proper electrolyte balance is essential for normal cellular function.

3. Role in Nerve Transmission and Muscle Contraction

  • Sodium and potassium are essential for generation and propagation of nerve impulses.

  • Calcium and magnesium play a key role in muscle contraction and relaxation.

  • Imbalance can lead to muscle cramps, weakness, or paralysis.

4. Enzyme Activation and Cofactor Functions

  • Many minerals act as enzyme cofactors, enhancing catalytic activity.

  • Examples include:

    • Magnesium for kinases and ATP-dependent enzymes

    • Zinc for dehydrogenases and DNA/RNA polymerases

    • Iron and copper in oxidoreductase enzymes

5. Role in Oxygen Transport and Storage

  • Iron is a vital component of hemoglobin and myoglobin.

  • It facilitates oxygen transport in blood and oxygen storage in muscles.

  • Iron deficiency leads to reduced oxygen-carrying capacity.

6. Hormone Synthesis and Action

  • Iodine is essential for synthesis of thyroid hormones (T₃ and T₄).

  • Minerals such as zinc and chromium influence insulin action and glucose metabolism.

  • Some minerals regulate hormone receptor function.

7. Acid–Base Balance

  • Minerals such as phosphates, bicarbonates, and chloride ions help maintain blood pH.

  • They act as buffer systems to prevent drastic changes in hydrogen ion concentration.

8. Blood Clotting (Coagulation)

  • Calcium (Factor IV) is essential for multiple steps in the coagulation cascade.

  • Deficiency may result in delayed clotting and bleeding tendencies.

9. Antioxidant Defense

  • Trace minerals like selenium, zinc, copper, and manganese are components of antioxidant enzymes.

  • Examples include:

    • Glutathione peroxidase (selenium)

    • Superoxide dismutase (zinc, copper, manganese)

  • These protect cells from oxidative stress.

10. Growth, Development, and Immunity

  • Minerals such as zinc, iron, and selenium are essential for cell division and immune function.

  • They support wound healing, resistance to infections, and normal growth.

Classification of Minerals

  1. Macrominerals: Required in amounts greater than 100 mg per day.
    • Calcium (Ca)
    • Phosphorus (P)
    • Magnesium (Mg)
    • Sodium (Na)
    • Potassium (K)
    • Chloride (Cl)
  2. Microminerals (Trace Minerals): Required in amounts less than 100 mg daily.
    • Iron (Fe)
    • Zinc (Zn)
    • Copper (Cu)
    • Manganese (Mn)
    • Selenium (Se)
    • Iodine (I)

Macrominerals

Calcium

Calcium is the most abundant mineral in the human body, accounting for about 1–2% of total body weight. Nearly 99% of calcium is present in bones and teeth, while the remaining 1% is found in blood, extracellular fluid, and soft tissues, where it plays vital regulatory roles.

Biochemical Functions of Calcium

A. Structural Functions

  • Major constituent of bones and teeth in the form of hydroxyapatite crystals
    (Ca₁₀(PO₄)₆(OH)₂)

  • Provides strength, rigidity, and mechanical support to the skeleton

B. Role in Muscle Contraction

  • Essential for excitation–contraction coupling

  • Regulates interaction between actin and myosin

  • Required for contraction of:

    • Skeletal muscle

    • Cardiac muscle

    • Smooth muscle

C. Nerve Transmission

  • Facilitates release of neurotransmitters at synaptic junctions

  • Maintains normal nerve excitability

  • Low calcium increases neuronal excitability → tetany

D. Blood Coagulation

  • Calcium acts as Factor IV in the coagulation cascade

  • Required for activation of several clotting factors

E. Enzyme Activation

  • Acts as a cofactor for enzymes such as:

    • ATPase

    • Phospholipase

  • Involved in intracellular signaling via calcium–calmodulin complex

F. Hormonal Secretion & Cell Signaling

  • Essential for secretion of hormones (e.g., insulin)

  • Acts as a second messenger in many signal transduction pathways

Dietary Requirements of Calcium

Age / Condition Requirement (mg/day)
Adults 1000 mg
Adolescents 1200–1300 mg
Pregnant women 1200 mg
Lactating mothers 1200–1500 mg
Elderly 1200 mg

 

Dietary Sources of Calcium

A. Animal Sources

  • Milk and milk products (best source)

    • Milk

    • Curd

    • Cheese

    • Butter milk

  • Fish with bones (sardines)

B. Plant Sources

  • Green leafy vegetables (spinach, broccoli)

  • Ragi (finger millet)

  • Sesame seeds

  • Soybeans and tofu

  • Nuts (almonds)

Absorption of Calcium

  • Occurs mainly in the duodenum and jejunum

  • Two mechanisms:

    • Active transport (vitamin D–dependent)

    • Passive diffusion

  • About 20–40% of dietary calcium is absorbed

  • Absorption is highest during growth, pregnancy, and lactation

Factors Promoting Calcium Absorption

  • Vitamin D (Calcitriol) – most important factor

  • Adequate gastric acidity

  • Lactose (especially in infants)

  • Optimal Ca : P ratio (1:1 to 2:1)

  • Growth hormone, estrogen

  • Low dietary calcium (adaptive increase in absorption)

Factors Inhibiting Calcium Absorption

  • Phytates (cereals, bran)

  • Oxalates (spinach, chocolate)

  • Excess dietary phosphate

  • Fat malabsorption (formation of calcium soaps)

  • Vitamin D deficiency

  • Alkaline pH of intestine

  • Excess fiber intake

Disease States Related to Calcium

A. Hypocalcemia

(Serum Ca < 8.5 mg/dL)

Causes:

  • Vitamin D deficiency

  • Hypoparathyroidism

  • Chronic kidney disease

  • Malabsorption syndromes

Clinical Features:

  • Tetany

  • Muscle cramps

  • Carpopedal spasm

  • Convulsions

  • Positive Chvostek’s and Trousseau’s signs

B. Rickets

  • Occurs in children

  • Due to vitamin D deficiency

  • Defective mineralization of growing bones

Features:

  • Bow legs

  • Delayed dentition

  • Rachitic rosary

  • Soft skull bones (craniotabes)

C. Osteomalacia

  • Occurs in adults

  • Defective mineralization of bone matrix

Features:

  • Bone pain

  • Fragility fractures

  • Muscle weakness

D. Osteoporosis

  • Common in postmenopausal women and elderly

  • Reduced bone mass with normal mineralization

Risk Factors:

  • Estrogen deficiency

  • Low calcium intake

  • Sedentary lifestyle

E. Hypercalcemia

(Serum Ca > 10.5 mg/dL)

Causes:

  • Hyperparathyroidism

  • Malignancy

  • Excess vitamin D intake

Clinical Features:

  • Kidney stones

  • Polyuria and polydipsia

  • Constipation

  • Neuropsychiatric symptoms

 

Phosphorus

Phosphorus is the second most abundant mineral in the human body after calcium. About 85% of phosphorus is present in bones and teeth, while the remaining amount is distributed in soft tissues and body fluids. It plays a central role in energy metabolism, nucleic acid synthesis, and acid–base balance.

Biochemical Functions of Phosphorus

A. Structural Functions

  • Present in bones and teeth as calcium phosphate and hydroxyapatite

  • Provides rigidity and strength to skeletal system

B. Role in Energy Metabolism

  • Essential component of ATP, ADP, and AMP

  • Involved in energy storage and transfer

  • Plays a key role in oxidative phosphorylation

C. Component of Nucleic Acids

  • Forms the phosphate backbone of DNA and RNA

  • Essential for cell division and protein synthesis

D. Cell Membrane Structure

  • Constituent of phospholipids (phosphatidylcholine, phosphatidylserine)

  • Maintains membrane integrity and permeability

E. Acid–Base Balance

  • Acts as an important buffer system (phosphate buffer)

  • Helps maintain physiological pH of blood and tissues

F. Enzyme Regulation

  • Required for phosphorylation and dephosphorylation reactions

  • Regulates activity of enzymes and signaling proteins

G. Oxygen Delivery

  • Part of 2,3-bisphosphoglycerate (2,3-BPG) in RBCs

  • Facilitates oxygen release from hemoglobin

Dietary Requirements of Phosphorus

Age / Condition Requirement (mg/day)
Adults 700 mg
Adolescents 1250 mg
Pregnant women 700 mg
Lactating mothers 700 mg
Elderly 700 mg

 

Dietary Sources of Phosphorus

A. Animal Sources

  • Milk and milk products

  • Meat

  • Fish

  • Poultry

  • Eggs

B. Plant Sources

  • Cereals and whole grains

  • Pulses and legumes

  • Nuts and seeds

  • Soybeans

Note: Phosphorus from plant sources may be less bioavailable due to phytate binding.

Absorption of Phosphorus

  • Absorbed mainly in the duodenum and jejunum

  • Absorption occurs by:

    • Active transport (vitamin D-dependent)

    • Passive diffusion

  • About 60–70% of dietary phosphorus is absorbed

  • Absorption is generally efficient compared to calcium

Factors Promoting Phosphorus Absorption

  • Vitamin D (Calcitriol)

  • Adequate dietary intake

  • Growth and increased metabolic demand

  • Normal intestinal function

  • Proper calcium–phosphorus balance

Factors Inhibiting Phosphorus Absorption

  • Excess dietary calcium (forms insoluble Ca-phosphate)

  • Phytates in cereals and legumes

  • Aluminium-containing antacids

  • Vitamin D deficiency

  • Chronic diarrhea or malabsorption

Disease States Related to Phosphorus

A. Hypophosphatemia

(Serum phosphorus < 2.5 mg/dL)

Causes:

  • Vitamin D deficiency

  • Malnutrition

  • Chronic alcoholism

  • Diabetic ketoacidosis (recovery phase)

  • Hyperparathyroidism

Clinical Features:

  • Muscle weakness

  • Bone pain

  • Osteomalacia

  • Rickets in children

  • Hemolysis and impaired oxygen delivery

B. Rickets

  • Occurs in children

  • Due to deficiency of vitamin D, calcium, or phosphorus

  • Leads to defective mineralization of growing bones

Features:

  • Bowing of legs

  • Delayed dentition

  • Rachitic rosary

C. Osteomalacia

  • Occurs in adults

  • Softening of bones due to defective mineralization

Features:

  • Bone pain

  • Fragility fractures

  • Muscle weakness

D. Hyperphosphatemia

(Serum phosphorus > 4.5 mg/dL)

Causes:

  • Chronic kidney disease

  • Hypoparathyroidism

  • Excess intake of phosphate laxatives

  • Tumor lysis syndrome

Clinical Features:

  • Hypocalcemia

  • Soft tissue calcification

  • Renal damage

  • Cardiovascular complications

E. Chronic Kidney Disease–Mineral Bone Disorder (CKD-MBD)

  • Reduced phosphate excretion

  • Secondary hyperparathyroidism

  • Bone demineralization and fractures

 

Magnesium 

Magnesium is an essential macromineral and the fourth most abundant cation in the human body. About 60–70% of magnesium is present in bones, 20–30% in muscles and soft tissues, and <1% in extracellular fluid. It plays a vital role in enzyme activation, energy metabolism, neuromuscular function, and ion transport.

Biochemical Functions of Magnesium

A. Cofactor for Enzymes

  • Acts as a cofactor for more than 300 enzymes

  • Required for enzymes involved in:

    • Glycolysis

    • TCA cycle

    • Oxidative phosphorylation

  • Essential for ATP-dependent reactions (Mg-ATP complex)

B. Energy Metabolism

  • Magnesium stabilizes ATP

  • Required for ATP synthesis, storage, and utilization

  • Plays a key role in cellular energy transfer

C. Nucleic Acid and Protein Synthesis

  • Required for DNA and RNA synthesis

  • Essential for ribosomal function and protein synthesis

D. Neuromuscular Function

  • Regulates nerve impulse transmission

  • Controls neuromuscular excitability

  • Acts as a physiological calcium antagonist

E. Muscle Contraction and Relaxation

  • Involved in muscle relaxation

  • Prevents excessive calcium-mediated contraction

  • Deficiency leads to muscle cramps and tremors

F. Bone Mineralization

  • Present in bone matrix

  • Influences bone strength and structure

  • Regulates calcium metabolism

G. Electrolyte Balance

  • Maintains intracellular levels of:

    • Potassium

    • Calcium

  • Essential for normal cardiac rhythm

Dietary Requirements of Magnesium

Age / Condition Requirement (mg/day)
Adult males 400–420 mg
Adult females 310–320 mg
Pregnant women 350–360 mg
Lactating mothers 310–360 mg
Elderly ~400 mg

 

Dietary Sources of Magnesium

A. Plant Sources (Richest)

  • Green leafy vegetables (chlorophyll contains Mg)

  • Whole grains

  • Pulses and legumes

  • Nuts and seeds (almonds, cashews)

  • Bananas

B. Animal Sources

  • Milk and milk products

  • Meat

  • Fish

Absorption of Magnesium

  • Occurs mainly in the small intestine (jejunum and ileum)

  • Absorbed by:

    • Passive diffusion

    • Active transport

  • About 30–50% of dietary magnesium is absorbed

  • Kidneys play a major role in magnesium homeostasis

Factors Promoting Magnesium Absorption

  • Adequate dietary intake

  • Vitamin D (to some extent)

  • Normal intestinal function

  • Increased physiological demand

  • Low body magnesium levels

Factors Inhibiting Magnesium Absorption

  • Phytates and oxalates

  • Chronic diarrhea

  • Alcoholism

  • High calcium or phosphate intake

  • Malabsorption syndromes

  • Certain drugs (diuretics, proton pump inhibitors)

Disease States Related to Magnesium

A. Hypomagnesemia

(Serum Mg < 1.5 mg/dL)

Causes:

  • Malnutrition

  • Chronic alcoholism

  • Prolonged diarrhea

  • Diuretics

  • Malabsorption

Clinical Features:

  • Muscle cramps

  • Tremors

  • Tetany

  • Cardiac arrhythmias

  • Seizures

  • Hypocalcemia and hypokalemia

B. Neuromuscular Hyperexcitability

  • Increased nerve firing

  • Muscle spasms

  • Often associated with hypocalcemia

C. Cardiac Arrhythmias

  • Magnesium deficiency predisposes to:

    • Ventricular arrhythmias

    • Torsades de pointes

D. Hypermagnesemia

(Serum Mg > 2.5 mg/dL)

Causes:

  • Renal failure

  • Excess intake of magnesium-containing antacids or laxatives

Clinical Features:

  • Muscle weakness

  • Hypotension

  • Bradycardia

  • Respiratory depression

  • Cardiac arrest (severe cases)

Clinical Uses of Magnesium

  • Magnesium sulfate in:

    • Eclampsia

    • Torsades de pointes

    • Severe asthma

  • Treatment of hypomagnesemia

 

Sodium

Sodium is the major extracellular cation and an essential macromineral required for the maintenance of fluid balance, nerve conduction, muscle contraction, and acid–base equilibrium. It plays a central role in osmotic pressure regulation and cellular homeostasis.

Biochemical Functions of Sodium

A. Maintenance of Osmotic Pressure

  • Sodium is the primary determinant of extracellular fluid (ECF) volume

  • Regulates water distribution between intracellular and extracellular compartments

B. Nerve Impulse Transmission

  • Essential for generation and propagation of action potentials

  • Sodium influx causes depolarization of nerve and muscle membranes

C. Muscle Contraction

  • Required for normal muscle excitability

  • Works in coordination with potassium and calcium

D. Acid–Base Balance

  • Sodium salts (NaHCO₃, Na₂HPO₄) act as buffer systems

  • Helps maintain physiological pH

E. Active Transport Mechanisms

  • Sodium gradient drives:

    • Na⁺/K⁺-ATPase pump

    • Secondary active transport of glucose and amino acids

F. Regulation of Blood Pressure

  • Influences plasma volume and arterial pressure

  • Excess sodium intake is linked to hypertension

Dietary Requirements of Sodium

Age / Condition Requirement
Adults 1500 mg/day
Upper safe limit < 2300 mg/day
Pregnant women 1500 mg/day
Lactating mothers 1500 mg/day
Athletes / heavy sweating Increased requirement

1 g sodium = 2.5 g common salt (NaCl)

Dietary Sources of Sodium

A. Natural Sources

  • Milk

  • Meat

  • Eggs

  • Vegetables

B. Added / Processed Sources

  • Common salt (NaCl)

  • Pickles

  • Processed foods

  • Canned foods

  • Snacks and fast food

Absorption of Sodium

  • Sodium is rapidly and efficiently absorbed

  • Absorption occurs mainly in the small intestine

  • Mechanisms include:

    • Passive diffusion

    • Active transport

    • Co-transport with glucose and amino acids

  • Absorption efficiency is >95%

Factors Promoting Sodium Absorption

  • Presence of glucose and amino acids

  • Normal intestinal mucosa

  • Aldosterone (renal conservation, not intestinal absorption)

  • Increased dietary intake

Factors Inhibiting Sodium Absorption / Causing Loss

  • Chronic diarrhea and vomiting

  • Excessive sweating

  • Diuretics

  • Adrenal insufficiency

  • Intestinal malabsorption disorders

Disease States Related to Sodium

A. Hyponatremia

(Serum Na⁺ < 135 mEq/L)

Causes:

  • Excess water intake

  • Prolonged vomiting or diarrhea

  • Diuretic therapy

  • SIADH (Syndrome of Inappropriate ADH Secretion)

Clinical Features:

  • Nausea and vomiting

  • Headache

  • Confusion

  • Muscle cramps

  • Seizures (severe cases)

B. Hypernatremia

(Serum Na⁺ > 145 mEq/L)

Causes:

  • Water deprivation

  • Excess sodium intake

  • Diabetes insipidus

  • Severe dehydration

Clinical Features:

  • Thirst

  • Dry mucous membranes

  • Irritability

  • Restlessness

  • Coma (severe cases)

C. Hypertension

  • Chronic high sodium intake causes:

    • Increased plasma volume

    • Increased peripheral resistance

  • Major risk factor for:

    • Cardiovascular disease

    • Stroke

    • Kidney disease

Hormonal Regulation of Sodium Balance

  • Aldosterone: Increases sodium reabsorption in kidneys

  • ADH (Vasopressin): Regulates water balance

  • ANP (Atrial Natriuretic Peptide): Promotes sodium excretion

 

Potassium

Potassium is the major intracellular cation of the body and an essential macromineral. About 98% of total body potassium is present inside cells, especially in muscle tissues. Potassium is crucial for maintenance of cell membrane potential, nerve impulse transmission, muscle contraction, and cardiac function.

Biochemical Functions of Potassium

A. Maintenance of Resting Membrane Potential

  • Potassium concentration gradient across the cell membrane determines the resting membrane potential

  • Essential for excitability of nerves and muscles

B. Nerve Impulse Transmission

  • Efflux of potassium is responsible for repolarization of nerve membranes

  • Works in coordination with sodium during action potentials

C. Muscle Contraction

  • Required for normal contraction of:

    • Skeletal muscle

    • Cardiac muscle

    • Smooth muscle

  • Maintains normal heart rhythm

D. Regulation of Acid–Base Balance

  • Potassium participates in H⁺–K⁺ exchange mechanisms

  • Helps maintain intracellular pH

E. Enzyme Activation

  • Activates several enzymes involved in:

    • Carbohydrate metabolism

    • Protein synthesis

F. Cellular Metabolism

  • Facilitates glycogen synthesis

  • Influences insulin secretion and action

Dietary Requirements of Potassium

Age / Condition Requirement
Adults 3500–4700 mg/day
Pregnant women 4700 mg/day
Lactating mothers 5100 mg/day
Athletes / heavy sweating Increased requirement

 

Dietary Sources of Potassium

A. Plant Sources (Richest)

  • Bananas

  • Oranges

  • Citrus fruits

  • Tomatoes

  • Potatoes

  • Green leafy vegetables

  • Pulses and legumes

B. Animal Sources

  • Meat

  • Fish

  • Milk and milk products

Absorption of Potassium

  • Potassium is rapidly and almost completely absorbed

  • Absorption occurs mainly in the small intestine

  • Absorption efficiency is >90%

  • Excess potassium is excreted mainly by the kidneys

Factors Promoting Potassium Absorption / Retention

  • Adequate dietary intake

  • Normal renal function

  • Insulin (drives potassium into cells)

  • Aldosterone (renal regulation)

Factors Inhibiting Potassium Absorption / Causing Loss

  • Chronic diarrhea and vomiting

  • Excessive sweating

  • Diuretic therapy (loop and thiazide diuretics)

  • Hyperaldosteronism

  • Laxative abuse

Disease States Related to Potassium

A. Hypokalemia

(Serum K⁺ < 3.5 mEq/L)

Causes:

  • Prolonged vomiting or diarrhea

  • Diuretic use

  • Hyperaldosteronism

  • Inadequate intake

Clinical Features:

  • Muscle weakness

  • Fatigue

  • Paralysis (severe cases)

  • Cardiac arrhythmias

  • Flattened T-wave on ECG

B. Hyperkalemia

(Serum K⁺ > 5.0 mEq/L)

Causes:

  • Renal failure

  • Potassium-sparing diuretics

  • Excess potassium intake

  • Acidosis

  • Tissue breakdown (burns, hemolysis)

Clinical Features:

  • Muscle weakness

  • Paresthesia

  • Life-threatening cardiac arrhythmias

  • Tall peaked T-waves on ECG

  • Cardiac arrest (severe cases)

C. Cardiac Arrhythmias

  • Both hypo- and hyperkalemia severely affect cardiac conduction

  • Potassium imbalance is a medical emergency

Hormonal Regulation of Potassium Balance

  • Aldosterone: Increases potassium excretion

  • Insulin: Promotes potassium entry into cells

  • Catecholamines: Shift potassium intracellularly

 

Chloride 

Chloride is the major extracellular anion and an essential macromineral. It usually exists in association with sodium and potassium and plays a vital role in maintenance of osmotic pressure, acid–base balance, gastric acid formation, and electrolyte equilibrium.

Biochemical Functions of Chloride

A. Maintenance of Osmotic Pressure

  • Chloride, along with sodium, regulates extracellular fluid volume

  • Maintains electrical neutrality in body fluids

B. Acid–Base Balance

  • Involved in chloride–bicarbonate exchange (Hamburger phenomenon)

  • Helps maintain blood pH

  • Regulates bicarbonate concentration in plasma

C. Formation of Gastric Hydrochloric Acid

  • Chloride combines with hydrogen ions to form HCl in gastric parietal cells

  • Essential for:

    • Activation of pepsinogen

    • Protein digestion

    • Absorption of iron and vitamin B₁₂

D. Nerve and Muscle Function

  • Helps maintain membrane potential

  • Assists in neuromuscular excitability

  • Participates in inhibitory neurotransmission

E. Transport of Carbon Dioxide

  • Chloride shift facilitates CO₂ transport from tissues to lungs

  • Essential for efficient gas exchange

Dietary Requirements of Chloride

Age / Condition Requirement
Adults 2300 mg/day
Pregnant women 2300 mg/day
Lactating mothers 2300 mg/day
Upper safe limit 3600 mg/day

Chloride requirement is usually met through common salt (NaCl) intake.

Dietary Sources of Chloride

A. Major Sources

  • Common salt (NaCl)

  • Processed and preserved foods

  • Pickles

  • Sauces and condiments

B. Natural Sources

  • Milk

  • Meat

  • Eggs

  • Vegetables

Absorption of Chloride

  • Chloride is rapidly and efficiently absorbed

  • Absorption occurs mainly in the small intestine

  • Absorption efficiency is >90%

  • Follows sodium absorption via electroneutral transport

Factors Promoting Chloride Absorption / Retention

  • Adequate sodium intake

  • Normal intestinal mucosa

  • Aldosterone (renal retention)

  • Acidic gastric environment

Factors Inhibiting Chloride Absorption / Causing Loss

  • Prolonged vomiting (loss of gastric HCl)

  • Chronic diarrhea

  • Excessive sweating

  • Diuretic therapy

  • Adrenal insufficiency

Disease States Related to Chloride

A. Hypochloremia

(Serum Cl⁻ < 98 mEq/L)

Causes:

  • Prolonged vomiting

  • Gastric suction

  • Diuretic use

  • Metabolic alkalosis

Clinical Features:

  • Muscle cramps

  • Weakness

  • Shallow breathing

  • Metabolic alkalosis

B. Hyperchloremia

(Serum Cl⁻ > 106 mEq/L)

Causes:

  • Dehydration

  • Excess saline infusion

  • Renal tubular acidosis

  • Metabolic acidosis

Clinical Features:

  • Deep and rapid breathing

  • Weakness

  • Confusion

  • Acid–base imbalance

C. Acid–Base Disorders

  • Chloride imbalance is commonly associated with:

    • Metabolic acidosis

    • Metabolic alkalosis

 

Microminerals

Iron 

Iron is an essential trace element required primarily for oxygen transport, cellular respiration, and enzymatic reactions. The total body iron content is about 3–5 g, most of which is present in hemoglobin, with the remainder stored in ferritin and hemosiderin or present in myoglobin and enzymes.

Biochemical Functions of Iron

A. Oxygen Transport

  • Iron is a constituent of hemoglobin

  • Responsible for reversible binding and transport of oxygen

B. Oxygen Storage

  • Present in myoglobin in muscle

  • Facilitates oxygen availability during muscle contraction

C. Role in Cellular Respiration

  • Component of cytochromes (a, b, c)

  • Essential for electron transport chain and ATP production

D. Enzyme Functions

  • Cofactor for several enzymes:

    • Catalase

    • Peroxidase

    • Cytochrome oxidase

  • Required for detoxification reactions

E. Hemopoiesis

  • Essential for RBC formation and maturation

  • Supports normal erythropoiesis

F. Immune Function

  • Required for normal immune response

  • Involved in proliferation of immune cells

Dietary Requirements of Iron

Age / Condition Requirement (mg/day)
Adult males 8–10 mg
Adult females 18 mg
Pregnant women 27 mg
Lactating mothers 9–10 mg
Children 7–10 mg

 

Dietary Sources of Iron

A. Heme Iron (Better Absorbed)

  • Liver

  • Red meat

  • Fish

  • Poultry

B. Non-Heme Iron

  • Green leafy vegetables

  • Pulses and legumes

  • Whole grains

  • Nuts and seeds

  • Dates and jaggery

Absorption of Iron

  • Absorbed mainly in the duodenum and upper jejunum

  • Heme iron is absorbed more efficiently

  • Non-heme iron must be reduced from Fe³⁺ to Fe²⁺

  • Absorption is regulated by body iron stores

Factors Promoting Iron Absorption

  • Vitamin C (ascorbic acid)

  • Gastric acid (low pH)

  • Presence of meat (meat factor)

  • Increased erythropoiesis

  • Iron deficiency state

Factors Inhibiting Iron Absorption

  • Phytates (cereals)

  • Oxalates

  • Tannins (tea, coffee)

  • Excess calcium

  • Antacids

  • Chronic inflammation

Transport and Storage of Iron

Transport

  • Iron is transported in plasma bound to transferrin

Storage

  • Stored as:

    • Ferritin (water-soluble)

    • Hemosiderin (insoluble)

Disease States Related to Iron

A. Iron Deficiency Anemia

(Most common nutritional deficiency)

Causes:

  • Poor dietary intake

  • Chronic blood loss

  • Increased requirement (pregnancy)

  • Malabsorption

Clinical Features:

  • Pallor

  • Fatigue

  • Breathlessness

  • Glossitis

  • Koilonychia (spoon nails)

B. Anemia of Chronic Disease

  • Iron trapped in macrophages

  • Normal or increased ferritin

  • Reduced serum iron

C. Hemochromatosis

(Iron overload disorder)

Causes:

  • Genetic (primary)

  • Repeated blood transfusions (secondary)

Clinical Features:

  • Liver cirrhosis

  • Diabetes mellitus

  • Skin pigmentation

  • Cardiomyopathy

D. Hemosiderosis

  • Excess iron deposition in tissues

  • Less tissue damage compared to hemochromatosis

 

Zinc

Zinc is an essential trace element involved in a wide range of biochemical, catalytic, structural, and regulatory functions. The total body zinc content is about 2–3 g, with highest concentrations in muscle, bone, skin, liver, pancreas, and prostate. Zinc is crucial for growth, immune function, wound healing, and gene expression.

Biochemical Functions of Zinc

A. Enzyme Cofactor

  • Zinc is a cofactor for over 300 enzymes

  • Important zinc-dependent enzymes include:

    • Carbonic anhydrase

    • Alkaline phosphatase

    • Alcohol dehydrogenase

    • DNA and RNA polymerases

B. Role in Protein and Nucleic Acid Synthesis

  • Required for DNA replication and transcription

  • Essential for cell division and growth

C. Gene Expression

  • Structural component of zinc finger proteins

  • Regulates gene transcription and hormone receptor binding

D. Immune Function

  • Essential for T-cell maturation

  • Enhances cell-mediated immunity

  • Deficiency leads to recurrent infections

E. Wound Healing

  • Required for collagen synthesis

  • Promotes tissue repair and regeneration

F. Growth and Sexual Maturation

  • Required for normal growth in children

  • Essential for spermatogenesis and testosterone synthesis

G. Sensory Functions

  • Necessary for taste (gustation) and smell (olfaction)

  • Deficiency causes hypogeusia

Dietary Requirements of Zinc

Age / Condition Requirement (mg/day)
Adult males 11 mg
Adult females 8 mg
Pregnant women 11–12 mg
Lactating mothers 12–13 mg
Children 5–10 mg

Dietary Sources of Zinc

A. Animal Sources (Better Absorbed)

  • Meat

  • Liver

  • Fish

  • Eggs

  • Milk and milk products

B. Plant Sources

  • Whole grains

  • Pulses and legumes

  • Nuts and seeds

  • Green leafy vegetables

Absorption of Zinc

  • Absorbed mainly in the small intestine (jejunum)

  • Absorption occurs via:

    • Carrier-mediated transport

    • Passive diffusion

  • About 20–40% of dietary zinc is absorbed

  • Absorption is influenced by dietary composition

Factors Promoting Zinc Absorption

  • Animal protein (meat factor)

  • Adequate dietary intake

  • Low phytate content

  • Increased physiological demand (growth, pregnancy)

Factors Inhibiting Zinc Absorption

  • Phytates (whole grains, cereals)

  • High dietary fiber

  • Excess iron or calcium supplementation

  • Chronic diarrhea

  • Alcoholism

Transport and Storage of Zinc

Transport

  • Transported in plasma bound to:

    • Albumin

    • α-macroglobulin

Storage

  • No specific storage form

  • Distributed in tissues bound to proteins and enzymes

Disease States Related to Zinc

A. Zinc Deficiency

Causes:

  • Inadequate dietary intake

  • Malabsorption syndromes

  • Chronic diarrhea

  • Alcoholism

  • Long-term parenteral nutrition without zinc

Clinical Features:

  • Growth retardation

  • Delayed sexual maturation

  • Poor wound healing

  • Dermatitis

  • Alopecia

  • Loss of taste and smell

  • Recurrent infections

B. Acrodermatitis Enteropathica

  • Rare genetic disorder

  • Impaired zinc absorption

  • Presents with:

    • Severe dermatitis

    • Diarrhea

    • Alopecia

  • Treated with lifelong zinc supplementation

C. Zinc Toxicity

Causes:

  • Excess supplementation

  • Industrial exposure

Clinical Features:

  • Nausea and vomiting

  • Abdominal pain

  • Interference with copper absorption

  • Secondary copper deficiency anemia

 

Copper

Copper is an essential trace element required for iron metabolism, connective tissue formation, antioxidant defense, and nervous system function. The total body copper content is about 80–100 mg, with the highest concentrations in the liver, brain, heart, kidneys, and muscles.

Biochemical Functions of Copper

A. Iron Metabolism

  • Copper is essential for iron absorption and utilization

  • Component of ceruloplasmin, which oxidizes Fe²⁺ to Fe³⁺ for binding with transferrin

  • Copper deficiency can cause secondary iron deficiency anemia

B. Enzyme Cofactor

Copper is a cofactor for several important enzymes:

  • Cytochrome c oxidase – cellular respiration

  • Superoxide dismutase (Cu-Zn SOD) – antioxidant defense

  • Tyrosinase – melanin synthesis

  • Lysyl oxidase – collagen and elastin cross-linking

  • Dopamine β-hydroxylase – catecholamine synthesis

C. Connective Tissue Formation

  • Required for cross-linking of collagen and elastin

  • Essential for bone strength, vascular integrity, and skin health

D. Antioxidant Defense

  • Copper-containing enzymes protect cells from oxidative damage

  • Works synergistically with zinc

E. Nervous System Function

  • Required for myelination and neurotransmitter synthesis

  • Essential for normal brain development

F. Pigmentation

  • Necessary for synthesis of melanin

  • Deficiency leads to hypopigmentation

Dietary Requirements of Copper

Age / Condition Requirement (mg/day)
Adults 0.9 mg
Pregnant women 1.0 mg
Lactating mothers 1.3 mg
Children 0.3–0.9 mg

 

Dietary Sources of Copper

A. Rich Sources

  • Liver

  • Shellfish

  • Nuts and seeds

  • Cocoa

  • Whole grains

B. Other Sources

  • Legumes

  • Green leafy vegetables

  • Drinking water (from copper pipes)

Absorption of Copper

  • Absorbed mainly in the stomach and small intestine

  • About 30–50% of dietary copper is absorbed

  • Absorption decreases with high intake

Factors Promoting Copper Absorption

  • Adequate dietary intake

  • Animal protein

  • Acidic gastric pH

  • Low body copper stores

Factors Inhibiting Copper Absorption

  • Excess zinc intake

  • High iron intake

  • Phytates

  • Chronic diarrhea

  • Malabsorption syndromes

Transport and Storage of Copper

Transport

  • Transported in plasma bound to:

    • Albumin (initial transport)

    • Ceruloplasmin (major circulating form)

Storage

  • Stored mainly in the liver

  • Excess copper excreted in bile

Disease States Related to Copper

A. Copper Deficiency

Causes:

  • Malnutrition

  • Malabsorption

  • Excess zinc intake

  • Long-term parenteral nutrition

Clinical Features:

  • Hypochromic anemia

  • Neutropenia

  • Bone abnormalities

  • Hypopigmentation

  • Neurological symptoms

B. Menkes Disease

  • X-linked genetic disorder

  • Defective copper absorption and transport

  • Leads to:

    • Kinky hair

    • Growth failure

    • Neurological deterioration

  • Usually fatal in early childhood

C. Wilson’s Disease

  • Autosomal recessive disorder

  • Excess copper accumulation in tissues

  • Defective biliary excretion of copper

Clinical Features:

  • Liver cirrhosis

  • Neurological symptoms

  • Kayser–Fleischer rings in eyes

  • Psychiatric manifestations

D. Copper Toxicity

Causes:

  • Excess supplementation

  • Industrial exposure

Clinical Features:

  • Gastrointestinal distress

  • Liver damage

  • Hemolysis (severe cases)

 

Manganese

Manganese is an essential trace required for enzyme activation, bone formation, metabolism of carbohydrates, amino acids, and cholesterol, and antioxidant defense. The total body manganese content is small, with highest concentrations in the liver, pancreas, kidneys, and bones.

Biochemical Functions of Manganese

A. Enzyme Cofactor

Manganese acts as a cofactor for several enzymes, including:

  • Pyruvate carboxylase – gluconeogenesis

  • Arginase – urea cycle

  • Superoxide dismutase (Mn-SOD) – mitochondrial antioxidant defense

  • Glycosyltransferases – proteoglycan synthesis

B. Carbohydrate, Lipid, and Protein Metabolism

  • Required for enzymes involved in:

    • Glucose metabolism

    • Fatty acid synthesis

    • Amino acid metabolism

C. Bone Formation and Growth

  • Essential for osteoblast function

  • Involved in bone matrix formation

  • Required for normal growth and skeletal development

D. Antioxidant Defense

  • Component of mitochondrial superoxide dismutase (Mn-SOD)

  • Protects cells from oxidative stress

E. Reproductive Function

  • Necessary for normal reproductive hormone synthesis

  • Supports fertility and normal sexual development

F. Nervous System Function

  • Required for normal brain function

  • Involved in neurotransmitter metabolism

Dietary Requirements of Manganese

Age / Condition Requirement (mg/day)
Adult males 2.3 mg
Adult females 1.8 mg
Pregnant women 2.0 mg
Lactating mothers 2.6 mg
Children 1.2–1.5 mg

 

Dietary Sources of Manganese

A. Rich Sources

  • Whole grains

  • Nuts and seeds

  • Tea

  • Legumes

  • Green leafy vegetables

B. Other Sources

  • Fruits

  • Spices

  • Drinking water (trace amounts)

Absorption of Manganese

  • Absorbed mainly in the small intestine

  • Absorption efficiency is low (3–5%)

  • Excess manganese is excreted mainly through bile

Factors Promoting Manganese Absorption

  • Low dietary manganese intake

  • Iron deficiency (increases Mn absorption)

  • Normal intestinal function

Factors Inhibiting Manganese Absorption

  • High dietary iron

  • High calcium intake

  • Phytates and fiber

  • Malabsorption syndromes

Transport and Storage of Manganese

Transport

  • Transported in plasma bound to:

    • Transferrin

    • Albumin

Storage

  • Stored mainly in the liver and bones

Disease States Related to Manganese

A. Manganese Deficiency

(Rare)

Causes:

  • Poor dietary intake

  • Long-term parenteral nutrition without Mn

Clinical Features:

  • Impaired growth

  • Skeletal abnormalities

  • Altered glucose metabolism

  • Reduced fertility

B. Manganese Toxicity

(Common in occupational exposure)

Causes:

  • Industrial inhalation (mining, welding)

  • Excess supplementation

Clinical Features:

  • Neurological symptoms (manganism)

  • Parkinson-like features

  • Tremors

  • Behavioral changes

C. Neurological Disorders

  • Excess manganese accumulates in basal ganglia

  • Leads to irreversible neurological damage

 

Selenium

Selenium is an essential trace element required in very small amounts for antioxidant defense, thyroid hormone metabolism, immune function, and reproductive health. Selenium is biologically active as selenoproteins, in which selenium is present as the amino acid selenocysteine.

Biochemical Functions of Selenium

A. Antioxidant Defense

  • Selenium is a component of glutathione peroxidase

  • Protects cells from oxidative damage by reducing hydrogen peroxide and lipid peroxides

  • Works synergistically with vitamin E

B. Thyroid Hormone Metabolism

  • Component of iodothyronine deiodinases

  • Converts thyroxine (T₄) to triiodothyronine (T₃)

  • Protects thyroid gland from oxidative stress

C. Immune Function

  • Enhances cell-mediated and humoral immunity

  • Supports proliferation of T lymphocytes

  • Improves resistance to infections

D. Reproductive Function

  • Required for normal spermatogenesis

  • Maintains sperm motility

  • Important for fertility

E. Cardiovascular Protection

  • Prevents oxidative damage to lipoproteins

  • May reduce risk of atherosclerosis

Dietary Requirements of Selenium

Age / Condition Requirement (µg/day)
Adults 55 µg
Pregnant women 60 µg
Lactating mothers 70 µg
Children 20–40 µg

 

Dietary Sources of Selenium

A. Rich Sources

  • Brazil nuts (very rich source)

  • Seafood

  • Organ meats

  • Eggs

B. Other Sources

  • Cereals and grains

  • Milk and dairy products

  • Vegetables (content depends on soil selenium)

Absorption of Selenium

  • Selenium is efficiently absorbed (≈80–90%)

  • Absorbed mainly in the small intestine

  • Organic forms (selenium in food proteins) are better absorbed than inorganic forms

Factors Promoting Selenium Absorption

  • Adequate protein intake

  • Organic selenium forms (selenocysteine, selenomethionine)

  • Normal intestinal function

Factors Inhibiting Selenium Absorption

  • Heavy metals (mercury, cadmium)

  • Poor intestinal absorption

  • High sulfur intake

  • Chronic diarrhea

Transport and Storage of Selenium

Transport

  • Transported in plasma bound to selenoprotein P

Storage

  • Stored in:

    • Liver

    • Kidney

    • Muscle

  • No large storage pool; regular intake required

Disease States Related to Selenium

A. Selenium Deficiency

Causes:

  • Low selenium content in soil

  • Malnutrition

  • Long-term parenteral nutrition

Clinical Features:

  • Keshan disease (cardiomyopathy)

  • Kashin–Beck disease (osteoarthropathy)

  • Muscle weakness

  • Increased susceptibility to infections

  • Hypothyroidism-like features

B. Keshan Disease

  • Endemic cardiomyopathy

  • Seen in selenium-deficient regions

  • Affects children and women of childbearing age

C. Selenium Toxicity (Selenosis)

Causes:

  • Excess supplementation

  • High intake from selenium-rich foods

Clinical Features:

  • Garlic-like breath odor

  • Hair loss

  • Brittle nails

  • Gastrointestinal upset

  • Neurological abnormalities

 

Iodine

Iodine is an essential trace (micromineral) required for the synthesis of thyroid hormones, which regulate basal metabolic rate, growth, development, and energy metabolism. The total body iodine content is about 15–20 mg, with nearly 70–80% stored in the thyroid gland.

Biochemical Functions of Iodine

A. Thyroid Hormone Synthesis

  • Iodine is an essential component of:

    • Thyroxine (T₄)

    • Triiodothyronine (T₃)

  • Required for iodination of tyrosine residues in thyroglobulin

B. Regulation of Basal Metabolic Rate (BMR)

  • Thyroid hormones regulate:

    • Energy expenditure

    • Oxygen consumption

    • Heat production

C. Growth and Development

  • Essential for normal physical growth

  • Critical for brain development, especially during fetal life and infancy

D. Nervous System Development

  • Required for myelination and neuronal differentiation

  • Deficiency during pregnancy leads to irreversible brain damage

E. Protein, Fat, and Carbohydrate Metabolism

  • Thyroid hormones influence:

    • Protein synthesis

    • Lipolysis

    • Glucose metabolism

Dietary Requirements of Iodine

Age / Condition Requirement (µg/day)
Adults 150 µg
Pregnant women 220 µg
Lactating mothers 290 µg
Children 90–120 µg

Dietary Sources of Iodine

A. Rich Sources

  • Iodized salt (major source)

  • Sea fish

  • Seaweed

B. Other Sources

  • Milk and dairy products

  • Eggs

  • Meat

  • Cereals and vegetables (iodine content depends on soil)

Absorption of Iodine

  • Iodine is absorbed in the small intestine

  • Absorption efficiency is >90%

  • Absorbed iodine circulates as iodide

  • Taken up by the thyroid via sodium–iodide symporter (NIS)

Factors Promoting Iodine Absorption and Utilization

  • Adequate dietary intake

  • Normal gastrointestinal function

  • Proper thyroid function

  • Adequate selenium status (for hormone activation)

Factors Inhibiting Iodine Absorption / Utilization

  • Goitrogens (thiocyanates in cabbage, cauliflower)

  • Excess intake of goitrogenic foods

  • Iodine deficiency

  • Certain drugs (amiodarone, lithium)

  • Smoking (thiocyanates)

Transport and Storage of Iodine

Transport

  • Transported in blood as iodide

Storage

  • Stored mainly in the thyroid gland

  • Incorporated into thyroglobulin

Disease States Related to Iodine

A. Iodine Deficiency Disorders (IDD)

Includes:

  • Endemic goiter

  • Hypothyroidism

  • Cretinism

  • Mental retardation

B. Goiter

  • Enlargement of thyroid gland

  • Due to inadequate iodine intake

  • Caused by increased TSH stimulation

C. Cretinism

  • Severe iodine deficiency during fetal life

  • Characterized by:

    • Mental retardation

    • Dwarfism

    • Deaf-mutism

    • Delayed sexual development

D. Hypothyroidism

  • Low levels of thyroid hormones

  • Features:

    • Weight gain

    • Cold intolerance

    • Lethargy

    • Bradycardia

E. Hyperthyroidism (Excess Iodine)

  • Excess iodine intake can trigger:

    • Iodine-induced hyperthyroidism

  • Seen in susceptible individuals

Prevention of Iodine Deficiency

  • Universal salt iodization

  • Health education

  • Monitoring iodine content in salt

MCQs

1. Minerals are best defined as:

A. Organic nutrients
B. Energy-yielding substances
C. Inorganic nutrients required for body functions
D. Vitamins

Answer: C

2. Minerals do NOT provide:

A. Structural support
B. Enzyme activation
C. Energy
D. Electrolyte balance

Answer: C

3. Minerals required in amounts greater than 100 mg/day are called:

A. Trace minerals
B. Ultratrace elements
C. Macrominerals
D. Micronutrients

Answer: C

4. Which of the following is a macromineral?

A. Zinc
B. Iron
C. Calcium
D. Selenium

Answer: C

5. Which mineral is the major extracellular cation?

A. Potassium
B. Calcium
C. Sodium
D. Magnesium

Answer: C

6. Which is the major intracellular cation?

A. Sodium
B. Potassium
C. Calcium
D. Chloride

Answer: B

7. The major extracellular anion is:

A. Bicarbonate
B. Phosphate
C. Chloride
D. Sulfate

Answer: C

8. About 99% of calcium is found in:

A. Blood
B. Muscles
C. Bones and teeth
D. Liver

Answer: C

9. Calcium is required for all EXCEPT:

A. Muscle contraction
B. Blood coagulation
C. Nerve transmission
D. Oxygen transport

Answer: D

10. Vitamin D primarily helps in absorption of:

A. Iron
B. Zinc
C. Calcium
D. Sodium

Answer: C

11. Which factor inhibits calcium absorption?

A. Vitamin D
B. Lactose
C. Phytates
D. Growth hormone

Answer: C

12. The second most abundant mineral in the body is:

A. Magnesium
B. Phosphorus
C. Sodium
D. Potassium

Answer: B

13. Phosphorus is an essential component of:

A. Hemoglobin
B. ATP
C. Vitamin D
D. Insulin

Answer: B

14. 2,3-BPG in RBCs contains:

A. Calcium
B. Iron
C. Phosphorus
D. Magnesium

Answer: C

15. Magnesium acts mainly as:

A. Structural mineral
B. Enzyme cofactor
C. Hormone
D. Buffer

Answer: B

16. Magnesium deficiency commonly causes:

A. Hypertension
B. Tetany
C. Muscle relaxation
D. Hypercalcemia

Answer: B

17. Iron is mainly absorbed in:

A. Ileum
B. Colon
C. Duodenum
D. Stomach

Answer: C

18. The transport protein for iron is:

A. Albumin
B. Ferritin
C. Transferrin
D. Ceruloplasmin

Answer: C

19. Storage form of iron is:

A. Hemoglobin
B. Transferrin
C. Ferritin
D. Cytochrome

Answer: C

20. Iron deficiency causes:

A. Megaloblastic anemia
B. Hemolytic anemia
C. Microcytic hypochromic anemia
D. Aplastic anemia

Answer: C

21. Zinc is required for:

A. Oxygen transport
B. Enzyme activation
C. Bone mineralization only
D. Gastric acid formation

Answer: B

22. Zinc deficiency commonly causes:

A. Night blindness
B. Loss of taste
C. Goiter
D. Anemia

Answer: B

23. Acrodermatitis enteropathica is due to deficiency of:

A. Copper
B. Zinc
C. Iron
D. Selenium

Answer: B

24. Copper is essential for:

A. Thyroid hormone synthesis
B. Iron metabolism
C. Sodium balance
D. Calcium absorption

Answer: B

25. Ceruloplasmin is associated with:

A. Iron transport
B. Copper metabolism
C. Zinc storage
D. Calcium regulation

Answer: B

26. Wilson’s disease is due to excess:

A. Iron
B. Zinc
C. Copper
D. Selenium

Answer: C

27. Manganese is a component of:

A. Hemoglobin
B. Glutathione peroxidase
C. Mn-superoxide dismutase
D. Cytochrome oxidase

Answer: C

28. Selenium acts mainly as:

A. Structural mineral
B. Antioxidant
C. Electrolyte
D. Hormone

Answer: B

29. Selenium is a component of:

A. Catalase
B. Glutathione peroxidase
C. Carbonic anhydrase
D. Tyrosinase

Answer: B

30. Keshan disease is associated with deficiency of:

A. Iodine
B. Selenium
C. Iron
D. Zinc

Answer: B

31. Iodine is essential for synthesis of:

A. Insulin
B. Cortisol
C. Thyroid hormones
D. Growth hormone

Answer: C

32. Major storage site of iodine is:

A. Liver
B. Kidney
C. Thyroid gland
D. Muscle

Answer: C

33. Iodine deficiency in children leads to:

A. Scurvy
B. Rickets
C. Cretinism
D. Pellagra

Answer: C

34. Goiter is caused by:

A. Excess iodine
B. Iodine deficiency
C. Selenium excess
D. Zinc deficiency

Answer: B

35. Sodium and potassium balance is mainly regulated by:

A. Insulin
B. Thyroxine
C. Aldosterone
D. Parathyroid hormone

Answer: C

36. Chloride is required for formation of:

A. Pepsin
B. Bile salts
C. Hydrochloric acid
D. Trypsin

Answer: C

37. Chloride shift occurs in:

A. Liver
B. Kidneys
C. RBCs
D. Intestine

Answer: C

38. Hypokalemia primarily affects:

A. Liver
B. Bone
C. Heart rhythm
D. Vision

Answer: C

39. Hyperkalemia may cause:

A. Hypertension
B. Cardiac arrest
C. Osteoporosis
D. Anemia

Answer: B

40. Sodium excess is commonly associated with:

A. Hypotension
B. Hypertension
C. Hypoglycemia
D. Anemia

Answer: B

41. Phytates reduce absorption of:

A. Sodium
B. Potassium
C. Iron and zinc
D. Chloride

Answer: C

42. Oxalates inhibit absorption of:

A. Iron
B. Calcium
C. Sodium
D. Selenium

Answer: B

43. Which mineral is required for blood coagulation?

A. Iron
B. Calcium
C. Zinc
D. Copper

Answer: B

44. The phosphate buffer system helps maintain:

A. Osmotic pressure
B. Blood glucose
C. Acid–base balance
D. Oxygen transport

Answer: C

45. Most abundant mineral in the body is:

A. Phosphorus
B. Calcium
C. Magnesium
D. Sodium

Answer: B

46. Minerals are absorbed mainly from:

A. Stomach
B. Colon
C. Small intestine
D. Rectum

Answer: C

47. Which mineral deficiency causes osteoporosis?

A. Iron
B. Zinc
C. Calcium
D. Sodium

Answer: C

48. Which mineral interacts with insulin action?

A. Chromium
B. Sodium
C. Chloride
D. Selenium

Answer: A

49. Ultratrace elements include:

A. Calcium
B. Zinc
C. Nickel
D. Iron

Answer: C

50. The best source of iodine in diet is:

A. Milk
B. Green vegetables
C. Iodized salt
D. Fruits

Answer: C