MICRONUTRIENTS

CONTENTS

Introduction

VitaminWater-Soluble VitaminWater-Unsoluble VitaminVitamin and Health

MineralMacroelementsMicroelementsMineral and Health

INTRODUCTION

Micronutrient:+ 45 essential they are necessary for life and

must be supplied by the diet because they cannot be synthesized in the human body.

are basic components of every cell in the bodyserve as chemical messengers, building blocks,

and enzymes.

are constantly being metabolized, broken down, and excreted and need to be quickly replaced.

INTRODUCTION

Micronutrient: because most are not stored in the body

in large amounts, regular daily intake is important to maintain tissue levels.

can treat illness or help prevent disease is by enhancing healthy pathways of cell metabolism

can now be divided into vitamins and minerals.

BIOCHEMICAL FUNCTION OF MICRONUTRIENTS: EXAMPLES OF CLASSICAL VS. NEWER ROLES

Factors that cause nutritional needs to vary from person to person

VITAMINS

Vitamins:are complex organic molecules required in

relatively small quantities.

either cannot be synthesised in the body at all, or they are synthesised in amounts too small so that they must be present in the diet to provide optimal levels.

a proportion of the vitamina requirement can be synthesised by the intestinal microorganisms.

VITAMINS

If adequate amounts of a vitamin are not present in diet, or if they are not adequately absorbed, a deficiency disease develops.

Since many of vitamins provide cofactors or prosthetic groups, in some cases symptoms of the disease can be traced to a low activity of a specific enzyme due to low level of vitamin.

Vitamins are divided into two groups:Water-unsoluble vitamins: A,D, E, KWater-soluble vitamins: B komplex and C

VITAMIN A

Retinol, retinal, and retinoic acid are collectively as vitamin A.

In the blood, vitamin A is bound by retinol-binding protein (RBP)

Vitamin A in animal foods is mainly in form of retinol combined with fatty acids

In body retinol can be converted to retinal or retinoic acid.

Retinal plays a central role in function of retina Retinoic acid helps regulate gene expression and

cell development.

FUNCTIONS OF VITAMIN A

1. Vision. Retinal epithelium are rich in retinal. When light enters eye, retinal absorbs energy and changes shape, triggering a nerve impulse

2. Skin and mucus membrane health. Vitamin A promotes proper growth and development of cells lining skin and mucous membranes in respiratory, gastrointestinal, and genitourinary tracts

3. Immune system. Vitamin A: maintain integrity of skin and mucous membrane

barriers against bacteria, viruses, and parasites. I enhances antibody production by white blood cells and

increases number and activity of T cells

FUNCTIONS OF VITAMIN A

4. Hormone synthesis. Vitamin A is required for steroid hormone synthesis (corticosteroids and androgens and estrogens)

5. Reproduction. Optimum vitamin A status maintains sperm count and motility in males. In females, deficiency is associated with infertility and spontaneous abortion.

6. Growth and development. Vitamin A controls cell growth and development.

FUNCTIONS OF VITAMIN A

7. Red blood cells. Vitamin A plays an important role in mobilizing iron stores to build new red blood cells.

8. Nervous system. Vitamin A helps maintain protective myelin both in peripheral nerves and in the brain.

9. Skeleton. Vitamin A participates in bone formation, particularly during childhood growth and during fracture healing.

VITAMIN D

Function of vitamin D:1. Skeletal health. Vitamin D:

is essential for normal bone growth during childhood and maintain bone density and strength during adulthood.

enhances calcium absorption and increases calcium and mineral deposition into skeleton.

2. Cell growth and development. Vitamin D is an important regulator of cell development (particularly in white blood cells and epithelial cells).

3. Immune system. Vitamin D enhances the activity and response of white blood cells in infection

VITAMIN E AND FUNCTION

Vitamin E is a a group of alpha-tocopherol, beta-tocopherols, gammatocopherols, and delta-tocopherolscompounds

The most abundant and active form of vitamin E is alpha-tocopherol

1. Antioxidant action. Vitamin E scavenges free radicals. It with glutathione peroxidase and vitamin C in limite free radical damage.

2. Antithrombotic action. Vitamin E slows down action of thrombin and reduces platelet aggregation by inhibiting thromboxane

VITAMIN K AND FUNCTION

Two forms of vitamin K: vitamin K1 (phylloquinone) is found in plant foods and vitamin K2 (menaquinone) is derived from animal and bacterial sources.

Bacteria in human colon synthesize menaquinones, which can be absorbed.

1. Blood coagulation. Vitamin K is an essential cofactor of factors II, VII, IX, X for blood coagulation.

2. Bone metabolism. Vitamin K is a cofactor of osteocalcin that regulates calcium metabolism and vitamin D activity at sites of bone turnover.

THIAMIN (VITAMIN B1) AND FUNCTION

1. Energy metabolism. Thiamin, as its active form TPP is a vital coenzyme in the production of energy in cells.

2. Nervous system. Thiamin in nerve cell membrane is important for transmission of nerve impulses in brain and peripheral. Thiamin also plays an important role in the metabolism of acetylcholine and serotonin.

3. Protein synthesis. Thiamin is important in synthesis of collagen

RIBOFLAVIN (VITAMIN B2) AND FUNCTION

1. Energy production. Riboflavin : is an essential part of flavin mononucleotide

(FMN) and flavin-adenine dinucleotide (FAD). FAD and FMN play central roles in metabolic

pathways of carbohydrate, fatty acid, and protein metabolism.

FAD and FMN are important in AT) production through cellular respiration in mitochondria.

2. Antioxidant action. Riboflavin is a cofactor of glutathione reductase that helps recycle oxidized glutathione, maintaining tissue antioxidant defenses

NIACIN (VITAMIN B3) AND FUNCTION

Two main forms of niacin in foods are nicotinic acid and nicotinamide.

Intake of 60 mg tryptophan can be converted into 1 mg niasin by liver.

1. Cellular metabolism. Niacin: participates in biosyntheses of fatty acids

and steroids is vital for breakdown of fuel for energy. plays important roles in supporting health of

the skin and mucous membranes, nervous system, and digestive system.

NIACIN (VITAMIN B3) AND FUNCTION

2. DNA replication and repair. Niacin is vital for synthesis of histones that are found in cell nuclei closely bound to DNA.

3. Antioxidant functions. Niacin plays an important role in the body’s antioxidant systems, particularly in the liver.

4. Blood sugar regulation. Niacin is a component of the glucose tolerance factor (GTF), that, together with insulin, helps to control blood glucose.

5. Fat and cholesterol metabolism. Nicotinic acid lower total and LDL and increase HDL.

VITAMIN B6

Vitamin B6 (pyridoxine) from diet is converted in body to pyridoxal-5-phosphate (PLP).

Function PLP:1. Protein synthesis. PLP plays a central role in

metabolism and interconversion of amino acids and synthesis of new proteins.

2. Maintenance of normal blood sugar levels. PLP is vital for conversion of protein and carbohydrate stores into glucose to support blood sugar between meals.

Function PLP:3. Niacin formation. PLP is essential for

conversion of tryptophan to niacin.

4. Lipid metabolism. PLP plays a central role in fat metabolism.

5. Red blood cell function. PLP is important in hemoglobin synthesis and oxygen transport by red blood cells.

6. Neurotransmitter synthesis. PLP is essential for formation of neurotransmitters, including serotonin (from trytophan), dopamine, and norepinephrine.

FOLIC ACID

Cell growth. Folate-containing coenzymes are essential to production of DNA and RNA in growing and dividing cells. So the cells rapidly turn over and are replaced, such as blood cells and cells lining digestive tract.

Protein metabolism. Folate plays a central role in interconversion of amino acids (homocysteine to methionine) and synthesis of structural and functional proteins.

Fetal growth and development. Folate plays a vital role in normal fetal development, particularly in formation of the central nervous system.

VITAMIN B12 AND FUNCTION Two dietary forms of vitamin B12 are

methylcobalamin and 5-deoxyadenosylcobalamin

The body contain only 2–5mg, and 50–90% of which is stored in liver.

1. Folate metabolism. Vitamin B12 is vital in activation of folate. In vitamin B12 deficiency, tissue stores of folate are “trapped” as inactive forms

2. Amino acid metabolism. Vitamin B12 is essential for conversion of homocysteine to methionine.

3. Fat metabolism. Vitamin B12 is a coenzyme in conversion of methylmalonate to succinate and is required for optimum fat metabolism in cells.

4. Cell replication. Together with folate, vitamin B12 is essential for the synthesis of nucleic acids and DNA synthesis.

5. Nervous system. Vitamin B12 is vital for synthesis of myelin, protective sheath surrounding many nerves in periphery, spinal cord, and brain.

6. Antioxidant status. Vitamin B12 helps maintain glutathione in reduced form necessary for its antioxidant functions

VITAMIN C (ASCORBIC ACID) AND FUNCTION

Human is unable to synthesize vitamin C1. Vitamin C plays an important role in body’s

ability to handle physiologic stress during infection, injury, or chronic disease.

2. Antioxidant function. Vitamin C is the body’s primary water-soluble antioxidant. It is present in body fluids, and inside all cells and helps protect against oxidation by free radicals.

3. Reduction of iron and copper. Vitamin C is important in conversion of iron and copper in many antioxidants enzyme (superoxide dismutase).

4. Collagen formation. Vitamin C is an essential coenzyme in collagen synthesis. Lack of ascorbic acid results in poorly formed connective tissue in skin, joints, muscles, and bones.

5. Carnitine synthesis. Ascorbic acid, together with niacin and vitamin B6, is essential for formation of carnitine, an amino acid required for breakdown of fats for energy.

6. Neurotransmitter synthesis. Ascorbic acid is essential for production of norepinephrine and serotonin, two important neurotransmitters in brain.

7. Detoxification and excretion of drugs and chemicals. Ascorbic acid helps maintain enzyme systems in liver that detoxify and excrete drugs and toxic (such as pesticides and heavy metals).

8. Immunocompetence. Vitamin C is important for healthy immune function. It is essential for optimum activity of white blood cells and production of chemical mediators that direct the immune response.

9. Cholesterol breakdown and excretion. Cholesterol levels in liver and blood increase if vitamin C status is impaired

10. Promotion of iron absorption. Vitamin C sharply increases non-heme iron absorption from diet or supplements.

11. Protection of folate and vitamin E from oxidation. Ascorbic acid protects folate and vitamin E from oxidation and helps maintain these vitamins in their active forms.

12. Body and blood histamine levels. Vitamin C plays a role in controlling low body and blood histamine levels. High levels of histamine can aggravate allergies, asthma, stomach ulcers, and certain psychiatric disorders.

13. Hormone production. Production of epinephrine and norepinephrineare dependent on vitamin C status.

CALCIUM

1. Bone and tooth structure. Ca with P forms hydroxyapatite crystals that give strength & rigidity to bone and tooth enamel (99% of Ca in keleton)

2. Blood clotting. Calcium is an important component of blood coagulation cascade.

3. Muscle contraction. In skeletal and heart muscle cells, calcium is an intracellular messenger that triggers contraction of muscle fibers

4. Nerve transmission. In nerve cells Ca plays a central role in depolarization of membranes and nerve transmission.

MAGNESIUM

60% Mg is in skeleton and about 30% in tissues (particularly in the liver, heart, and muscle).

1. Energy metabolism. Magnesium plays a central role in energy producing reactions in cells: breakdown and oxidation of glucose, fat, and proteins

2. Heart and muscles. Magnesium regulates calcium-triggered contraction of heart and muscle cells and is a physiologic calcium channel clocker.

3. Blood vessels. Magnesium can produce vasodilation of coronary and peripheral arteries and lower blood pressure.

4. Nervous system. Magnesium regulates nerve depolarization and transmission by controlling movement of ions (calcium, potassium) through ion channels in nerve membranes.

5. Bones and teeth. Magnesium, with calcium and phosphorus, is important for structure of bones and teeth.

POTASSIUM Body contains 30–40g of potassium; 98% is

contained within cells, most of it within skeletal muscle.

1. Energy metabolism. Potassium plays a central role in energy production in cells throughout the body.

2. Membrane excitability and transport. Nerve transmission, muscle contraction, and hormone secretion involves shifts of cellular P & electrical depolarization of cell membranes.

IRON Man has + 3.8g of iron and woman has + 2.3 g. 2/3 of it in hemoglobin and myoglobin. The

remainder is stored , primarily in bone marrow and liver.

1. Oxygen transport. Iron plays a critical role in

transferring oxygen from the lungs to tissues; 60% of body iron is in red blood cells as hemoglobin.

2. Muscle function. + 10% of body iron is in myoglobin in muscle cells. Myoglobin stores oxygen within muscle cells and releases it to provide energy during physical activity.

IRON

3. Energy production. Iron is an essential part of mitochondrial cytochromes that serve as electron carriers in the production of ATP

4. Enzyme function. Iron is a cofactor of cytochrome P450 in liverperoxidases catalases Other enzymes play roles in production of brain

neurotransmitters and thyroid hormone

ZINC

The body contain1.5–2.5 g.

1. Enzyme function. More than 200 zinc-dependent enzymes (RNA polymerases, alcohol dehydrogenase).

2. Structure and function of proteins. Zinc plays an important role in cell growth and differentiation and intracellular signaling.

3. Immune function. Zinc is important in production and regulation of cellular and humoral immune response.

4. Cytoprotection. Zinc provides protection against various toxic componds (organic toxins, heavy metals, radiation, and endotoxins produced by pathogenic bacteria)

5. Antioxidant function. Zinc is an essential part of the structure of copper/zinc superoxide dismutase (Cu/Zn SOD) that protect cell lipids from peroxidation and breakdown

MANGANESE

Adult has 200 – 400μmol of manganese, and most of it in bone, kidney, pancreas, and liver.

1. Carbohydrate metabolism. Synthesis of new glucose from pyruvate is dependent on manganese-containing enzymes.

2. Insulin production. Manganese is essential for normal insulin synthesis and secretion by pancreas.

3. Antioxidant protection. MnSOD is antioxidant enzyme

4. Protein metabolism. Manganese plays an essential role in the breakdown and excretion of excess nitrogen

5. Bone and cartilage synthesis. Synthesis of proteoglycans, important components of the connective tissues, cartilage, and bone, is dependent on manganese.

6. Enzyme activation. Manganese plays a role in nonspecific activation of many enzymes

COPPER

Adult contains 60–120mg of copper. Highest concentrations are found in the kidney, liver, brain, and heart.

Energy production. Copper is found in mitochondria of all cells. It is essential for energy production and, as a cofactor of cytochrome c oxidase

Iron metabolism. Copper is required for normal mobilization and transfer of iron from storage to bone marrow for erythropoesis.

Connective-tissue synthesis. Synthesis of collagen & elastin in connective tissue requires copper-containing enzyme, lysyl oxidase.

Antioxidant protection. Ceruloplasmin contain a cluster of copper that is a potent scavenger of free radicals.

Pigment production. Synthesis of melanin is dependent on copper.

Metabolism of hormones & neurotransmitters. Copper-containing enzymes are required for synthesis of epinephrine & norepinephrine in adrenal and nervous system.

IODINE

Thyroid hormone synthesis. Iodine The only known function of iodine in body is as an essential component of thyroid hormones.

Thyroid hormones are important regulators of cell activity and growth, both in utero and throughout life.

Although they affect all tissues, they are particularly important in the development of e nervous and skeletal systems.

SELENIUM Selenium is a component of several enzyme

systems. Liver and kidney contain high amounts.

1. Antioxidant protection. Selenium is a component of glutathione peroxidases.

2. Immune modulation. Selenium help regulate production of immunoglobulins (such as IgG) and tumor necrosis factor (TNF) and may enhance activity of natural killer (NK) cells.

3. Thyroid hormone metabolism. Convertion of T4 to T3 in liver and kidney is catalyzed by a selenium-containing type-I-iodothyronine-deiodinase.

FLUORIDE

Fluoride reduce in prevalence and severity of dental caries in both children and adults

1. Tooth structure. Fluoride: can be incorporated into crystalline structure of dental

enamel reduces solubility of enamel crystals increase their resistance to acid formed by oral

bacteria can enhance remineralization of damaged enamel.

2. Bone metabolism. Fluoride can enhance bone formation by stimulating osteoblast activity.

REFERENCES

Zimmermann M. 2001. Burgerstein’s Handbook of Nutrition. Micronutrients in the Prevention and Therapy of Disease. Thieme Stuttgart · New York, USA

Newsholme EA and Leech TR. 2010 Functional Biochemistry in Health and Disease. John Wiley & Sons