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What are Macronutrients and Micronutrients?
The nutrients can be divided into two major groups – “Macronutrients” and “Micronutrients”.
Macronutrients are those that are needed in large quantities (tens or hundreds of grams) every day. These are: Carbohydrates, protein and fats/oils.
Micronutrients are those that are needed in minute quantities (micrograms or at best milligrams). These are vitamins, minerals and trace elements.
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Vitamins
Vitamins are naturally occurring organic substances.
Their coenzyme forms are active and are essential in metabolic processes.
They serve nearly the same roles in all forms of life. The daily requirement of any vitamin depends on a number of factors and may increase during growth, pregnancy and lactation.
They are essential nutrients of humans, and have various roles in the human body
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Vitamins are either fat-soluble or water-soluble .
• Fat soluble vitamins are vitamins A, D, E and K.
• Water-soluble vitamins are the B-complex vitamins and vitamin C.
• B-complex vitamins are vitamin B1, B2, B6, B12,
niacin, folic acid, biotin and pantothenic acid.
•
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• Soluble vitamins, when taken in excess of body needs, are excreted in urine.
• On the other hand, fat-soluble vitamins, when taken in excess, are stored in the body (particularly liver) for use at times when the intake of these vitamins is inadequate.
• Most vitamins can be derived from liver, fruits, vegetables, legumes and grains.
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Vitamin A
Preformed retinoid is a collective term for retinol,
retinal, and retinoic acid, all of which are biologically
active.
Recommended Dietary Allowance Adult: 5000 IU/day Pregnancy lactation: 4000 IU/day Infants and children: 3000 IU/day
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Functions
1.Role of vitamin A in visionRetina of the eye contains two types of cellsRod cells (Vision in dim light)Cone cells (vision in bright light). Rod cells have a photosensitive pigment called rhodopsin, is a conjugated protein made up of opsin and 11-cis retinal
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2. Retinoic acid form of vitamin A maintains structural and functional integrity of epithelium
3. Retinol form of vitamin A is required for growth and reproductive function.
4. Retinol is also known to require for the formation of
bone and teeth.
Deficiency
Night blindness
Keratomalacia: Dryness of the cornea, corneal
epithelium becomes keratinised and opaque and may
become softened and ulcerated.
Follicular keratosis: Deficiency will affect hair follicles
and causes scaly skin
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Vitamin D
Sources
Fish liver oils, eggs, milk & butter
Sunlight induces synthesis of vit. D in the body from skin
cholesterol.
Required Dietary Allowance Children: 400 IU/day Adults: 400 IU/day Pregnancy and lactation: 400 IU/day Vitamin D2 or D3 are not active biologically but
converted to active form by hydroxylation [1,25 dihydroxyvitamin D3].
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Functions
Helps in the mineralization of bones by enhancing absorption
of calcium
Deficiency
The deficiency of vitamin D leads to rickets in children
Signs and symptoms are bowlegs, knock knee, pigeon
Chest, hypocalcemia and hypophosphatemia
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Vitamin E
SourcesVegetable oils, germinated whole-grain cereals
Required Dietary Allowance Adult male : 30 IU /day Female : 25 IU/day Children : 10-20 IU/day
Functions
1.Potent physiological antioxidant: Protects membranes with lipids from oxidative damage.
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2. Vitamin E, which is present in cell membranes, prevents the destructive non-enzymatic oxidation of polyunsaturated fatty acids (PUFA) by molecular oxygen, and it maintains the membrane integrity.
3.Protects erythrocytes from hemolysis by oxidizing agents (H2O2)
4. Required for normal reproduction in animals.5. Prevents liver necrosis and muscular dystrophy
Deficiency
Hemolysis of erythrocytes which may leads to anemia
Muscular weakness, fragile RBCs.
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Vitamin K
Phylloquinone, menaquinone and menadione are the
three forms of vitamin K
Sources Green leafy vegetables and Tomato, It is also synthesized by microorganisms in the
intestinal tract
Functions
Required for the maintenance of normal concentration
of blood clotting factors.
Deficiency
Excessive bleeding
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Vitamin C
Sources Citrus fruits (Orange, lemon), Tomatoes Strawberries Green vegetables Guava fruit
Required Dietary Allowance Adults: 60 mg/day Children: 40 mg/day.
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Functions
1. Collagen synthesis. Vitamin c is involved in the hydroxylation of proline and lysine residues, which are the collagen precursors.
2. It helps in the absorption of iron.
4. Acts as an antioxidant, scavenging the free radicals and reduces the nitrosamine formation.
5. The conversion of dopa to dopamine and dopamine to nor adrenaline requires vitamin C as an activator.
Deficiency Scurvy
Spongy gums , loose teeth, fragile blood vessels ,aching
swollen joints and delayed wound healing.
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Thiamin [Vitamin B1]
SourcesWhole grains (unpolished rice, wheat), legumes (Beans, peas) Meat.
Required Dietary Allowance Children: 1.2 mg/day Adults: 1.5 mg/day Pregnancy and lactation – 2.0 mg/day.
FunctionsThe coenzyme form of thiamine is Thiamin pyrophosphate (TPP)Helps to release energy from nutrients supports normal appetite and nerve function
TPP is required as coenzyme for Pyruvate dehydrogenasecomplex, α-ketoglutarate dehydrogenase complex,Transketolase etc.
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Deficiency
Cause:alcoholism and malnutrition
The overall picture of this vitamin deficiency including
neurological, cardiovascular and gastrointestinal
disorders is referred to as Beriberi
Beriberi is of four types Dry beriberi (peripheral neuritis) Wet beriberi (cardiac manifestation) Cerebral beriberi (Wernicke-Korsakoff’s syndrome) Infantile beriberi
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Sources Animal liver, yeast, green leafy vegetables, milk & eggs
Required Dietary Allowance Adults: 2.0 mg/day Children: 1.2 mg/day Pregnancy and lactation: 2.0 mg/day
The riboflavin has two coenzyme forms they are flavin mononucleotide (FMN). Flavin adenine dinucleotide (FAD) Some enzymes have FMN and FAD as their integral part. Such enzymes are called flavoproteins
Riboflavin[B2]
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Functions
Helps release energy from nutrients; supports health FMN is required for:
1. L-amino acid oxidase
2. Cytochrome C reductase.
FAD is required as coenzyme for:
1. Succinate dehydrogenase,
2. Pyruvate dehydrogenase complex,
3. α -ketoglutarate dehydrogenase complex,
4. Xanthine oxidase.
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Deficiency seen in: Malabsorption, malnutrition, and chronic alcoholism
Ariboflavinosis It is the medical condition caused by deficiency of
riboflavin. It is often associated with protein energy malnutrition and alcoholism.
Characterized by: Glossitis (Magenta colored tongue) Cheilosis (Fissuring of the lips) Fissuring at the corners of mouth, Seborrheic dermatitis, corneal vascularization are the
symptoms of riboflavin deficiency.
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Niacin [B3]
Sources Lean meats (liver) Legumes, peanuts (ground nuts) Green vegetables Whole grains. Amino acid tryptophan can be converted to the
coenzyme NAD. About 60 mg of tryptophan yields 1 mg of niacin.
Required Dietary Allowance Adults: 16-20 mg/day. Children: 9-16 mg/day Infants: 5-8 mg/day
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The coenzyme forms of niacin are Nicotinamide Adenine Dinucleotide (NAD) Nicotinamide Adenine Dinucleotide Phosphate (NADP).
FunctionsHelps release energy from nutrients; supports skin, nervousand digestive systemsNAD is required as a coenzyme for PDH complex, α-ketoglutarate dehydrogenase complex to mediate the reactions. NADP is required for glucose-6-phosphate dehydrogenase and 6-phosphate gluconate dehydrogenase mediated reactions.
Deficiency Pellagra which Involves skin, gastrointestinal tract and
central nervous system.
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Pyridoxine [B6]
Sources Whole grains, Poultry fish Potatoes Organ meats, Eggs Legumes.
Required Dietary Allowance Adults: 2.2 mg/day Children: 1.2 mg/day Infants: 3.0 mg/day
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Functions
Helps to make red blood cells
Helps in amino acid and fatty acid metabolism Coenzyme form of pyridoxine is pyridoxal
phosphate (PLP) PLP is required as coenzyme for the enzymes like Transaminases, Decarboxylases, Kynureninase, Cystathionine α-synthase, Cystathionine gamma-lyase and ALA synthase.
Deficiency Hypochromic microcytic anemia Glossitis Pigmented scaly dermatitis similar to pellagra
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Biotin [B7]
Sources Egg yolk Organ meats (liver, kidney) Milk Legumes Nuts
Required Dietary Allowance Adults: 0.3 mg/day. The intestinal bacteria also synthesize biotin to some
extent.
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Functions
Biotin itself functions as coenzyme in the reactions
involving fixation of CO2.
Helps release energy from carbohydrates; aids in fat
synthesis Pyruvate carboxylase Propionyl CoA carboxylase Acetyl CoA carboxylase
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Pantothenic acid [B5]
Sources Eggs, Animal liver,Meat , Milk, Vegetables and Grains.
Required Dietary Allowance Adults: 5-10 mg/day Children: 4-5 mg/day Infants: 1-2 mg/day
Conzyme form: Coenzyme A (CoASH): Required for Pyruvate dehydrogenase complex α-ketoglutarate DH complex Thiokinase Thiolase
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Sources Fresh green, Vegetables, Liver, Whole grains, Meat
Legumes.
Required Dietary Allowance Children - 300 µg/day Adults - 400 µg/day Pregnancy and lactation - 800 µg/day The coenzyme form of folic acid is tetrahydro folic
acid [THF] (FH4) is the active form.
The THF is a carrier of single carbon and it is involved in
single carbon transfer reactions
Folic acid
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Helps in the formation of DNA and new blood cells
including red blood cells
Deficiency• Megaloblastic anemia
The deficiency of folate leads to impairment of the methionine synthase reaction due to which purine ring synthesis is impaired. The impaired synthesis of DNA prevents cell division and formation of the nucleus of new red blood cells.
• Growth failure.
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Vitamin B12 or cobalamin
Sources
Liver,Meat, Fish, Eggs and Milk.
Human beings get small amount of vitamin B12 from
their intestinal flora.
Required Dietary Allowance Children: 2 µg/day Adults: 3 µ g/day Pregnancy and lactation: 4 µg/day.
Active form of Vitamin B12
Methylcobalamin and Deoxyadenosylcobalamin a
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Functions Vitamin B12 along with folic acid is required for the
development of red blood cells beyond megaloblastic stage.
It acts as coenzyme for the mutase enzyme which converts methyl malonyl CoA into succinyl CoA.
Methylcobalamin is required in the conversion of homocysteine to methionine
It is involved in the conversion of ribonucleotides to deoxyribonucleotide.
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Deficiency
Cause: malabsorption.
Pernicious anemia is caused by a deficiency of intrinsic
factor, which leads to impaired absorption of cobalamin. Megaloblastic anemia, Glossitis and inflammation of mouth, Methyl malonic aciduria.
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Minerals are vital to physical and mental development. They also help protect the body against infections.
Meat, fish, milk, cheese, green leafy vegetables and legumes provide most of the minerals needed by the body.
Minerals
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Minerals
Minerals are inorganic chemical elements present throughout the body in varying amounts. Like the vitamins, they cannot be synthesized in the body and must be taken with food.
Minerals act as co-factors of enzymes for metabolism.
Minerals form part of the structure of body tissues, such as bones, teeth and nails, blood, nerves and muscles.
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Calcium
Functions Mineralization of bones and teeth Regulator of many of the body’s biochemical processes Involved in blood clotting Involved in muscle contraction and relaxation Nerve function blood pressure and immune defenses Activates pancreatic lipase in the digestion of fats Serves as a second messenger in the action of
hormones like adrenaline.Serum ionic calcium level is maintained by vitamin D
and hormones like parathyroid hormone (PTH) and calcitonin.
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Action of Vitamin D
a. Increases the absorption of calcium (and phosphate) from the small intestine
b. Causes bone resorption.
Action of PTH on Kidney and Bone
1. PTH increases the activity of 1 α-hydroxylase in
kidney, which increases the synthesis of 1-25-dihydroxy
vitamin D3 and this in turn enhance the absorption of
calcium from intestine.
2. It increases the reabsorption of calcium from
glomerular filtrate in kidneys.
3. It causes the resorption of calcium from bone.
The above process helps maintain normal calcium level
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Hypocalcemia
This provokes a characteristic hyper excitable state of
the nerves and muscles called tetany.
Symptoms are:
• Numbness of extremities
• Emotional irritability
• Tightness and spasm of muscles.
– Hypocalcaemia also occurs in hypoparathyroidism, rickets, osteomalacia, pancreatitis, etc.
Hypercalcemia
Occurs in hyperparathyroidism and hypervitaminosis D.
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Phosphorous
Functions Mineralization of bones and teeth Part of every cell Used in energy transfer and maintenance of acid-base
Balance Helps in the formation of compounds like nucleic
acids,nucleotides like ATP, GTP, ADP It is also required in energy metabolism, synthesis of
phospholipids
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Hypophosphatemia
• Rickets
• Hyperparathyroidism
Clinical symptoms are muscle pain and weakness with
respiratory failure and decreased myocardial output
Hyperphosphatemia
• Seen in hypoparathyroidism
• Hypervitaminosis D
• Renal failure.
Elevated phosphate may cause a decrease in serum
concentration. Therefore it may lead to tetany and
seizures
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Sodium
Sodium (Na+) is the major cation of the extracellular fluid
Functions Maintains normal fluid and electrolyte balance Assists nerve impulse initiation and muscle contraction Helps in the active transport of glucose, galactose
and amino acids across intestinal mucosa and for
Na+/K+ ATPase.
Hyponatremia
Causes
• Kidney failure and defect in adrenal cortex
• Vomiting and diarrhea
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Syndrome of inappropriate secretion of antidiuretic
hormone (SIADH)
Hypernatremia
Causes: Hyperactivity of adrenal cortex
When water loss exceeds sodium loss, as occurs with
Dehydration.
Clinical symptoms: high blood pressure, fluid retention
and swelling
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Potassium
Most important cation of intracellular fluid
Functions Intracellular K+ is essential for a number of enzyme-
mediated reactions such as pyruvate kinase, glycogen synthesis and protein synthesis
The extracellular potassium is important for its
influence cardiac muscle
Hypokalemia and Hyperkalemia
Renal causes
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Chloride
Functions
Maintains normal fluid and electrolyte balance
It is involved in maintaining osmotic pressure
Hypochloremia: Metabolic alkalosis
Vomiting diarrhea, diuretics and gastric suction
Hyperchloremia :Metabolic acidosis
Dehydration, decreased renal blood flow, medications
ammonium chloride and Hyperparathyroidism
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Magnesium
Magnesium (Mg2+) is the major intracellular cation
Functions
• It is an essential activator of many enzymes especially those involving transfer of phosphate groups from ATP.
• Examples are hexokinase and phospho fructokinase.
• It also activates a number of enzymes like
– Enolase,
– Glucose-6-P dehydrogenase,
– Pyruvate carboxylase,
– Thiokinase,
– Glucose 6 Phospho gluconate dehydrogenase.
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Iron
Functions Iron is necessary for the synthesis of certain proteins Iron containing proteins in the body are of two types: Heme proteins (Hemoglobin, myoglobin, catalase
and cytochrome) and non-heme proteins (ferritin, transferrin, aconitase and sucinate dehydrogenase).
Essential in the formation of blood Involved in the transport and storage of oxygen in the
blood It is a cofactor bound to several non-heme enzymes
Required for the proper functioning of cells
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Ferritin is the storage form of iron and transferrin is
the transport form
Deficiency
Hypochromic microcytic anemia (microcytic RBC of
reduced size).
Causes: haemorrhage, malabsorption
Iron overload
Haemosiderosis and haemochromatosis
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Copper
Functions
A need for copper is linked to its functional role in
several copper containing enzymes.
1. Ceruloplasmin
2. Cytochrome oxidase
3. Dopamine-oxidase of catecholamine synthetic pathway.
4. Monoamine oxidase and diamine oxidase.
5. Cytoplasmic superoxide dismutase
6. Lysyl oxidase involved in cross-linking process in the conversion of tropocollagen to collagen.
7. Tyrosinase of melanin synthetic pathway is a Cu dependent enzyme.
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Deficiency
Hypochromic microcytic anemia
Wilson’s disease or Hepatolenticular degeneration
It is a fatal inherited disease.
Blood copper level decreases.
There is an excessive storage of copper in the liver,
kidney, brain and cornea
Menkes syndrome or Kinky-hair disease
It is a rare X-linked recessive disorder
Both serum copper and ceruloplasmin and liver copper
content are reduced.
Depigmentation of the skin and hair
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Zinc
Essential for normal growth, development and reproductionIt is required as an activator ion for:• Carbonic anhydrase • Alkaline phosphatase • Liver alcohol dehydrogenase • Carboxyl peptidase A • DNA polymerase• Cytosolic superoxide dismutase
DeficiencyDwarfism Acrodermatitis enteropathica: autosomal recessive disorder
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Manganese
Manganese acts as a cofactor or an activator
for several enzymes Acetyl CoA carboxylase Mitochondrial superoxide dismutase Arginase 6 Phosphate-gluconate dehydrogenase Squalene synthetase Isocitrate dehydrogenase Glutamine synthetase Kinases
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Selenium
It acts as an antioxidant:
It is an integral component of glutathione peroxidase.
This enzyme scavenging the free radicals and protect
the cells and membranes against oxidative damage.
So, this mineral complements the action of vitamin E.
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Iodine
Involved in the synthesis of thyroid hormones, triiodothyronine (T3) and tetraiodothyronine (t4), which influence a large number of metabolic functions.
Deficiency Cretinism in children: Severe iodine deficiency in mothersleads to intrauterine or neonatal hypothyroidism results inCretinism in their children, a condition characterized by mental retardation,dwarfism, slow growth
Endemic goitre in adults: It is an enlarged thyroid withdecreased thyroid hormone production.
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Fluoride
Involved in the formation of dental enamel and prevents
dental caries
Involved in the formation of teeth and skeleton
Inhibits osteoporosis in old age
Deficiency:
Dental caries and osteoporosis.
Excess fluoride causes fluorosis. In this condition there
is mottling of enamel. The mottled enamel is discolored,
corroded and pitted.