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Vitamin dan Mineral

dr. Syazili Mustofa, M. Biomed

Lektor mata kuliah ilmu biomedik

Departmen Biokimia dan Biologi Molekuler

FK Unila

Klasifikasivitamin

Vitamin

Larutair

Non B kompleks ( Vitamin C)

B kompleks

Pelepas Energi:

Tiamin (Vitamin B1)

Riboflavin (vitamin B2)

Niacin (vitamin B3)

Biotin

Pantothenic acid

Pembentukandarah:

Asam folat

Vit B12

Lain lain:

Vit B6

Pyridoxal

Pyridoxamine

Larut lemak:

Vitamin A ( Retinol ,Betakaroten)

Vitamin D (cholecalciferol)

Vitamin K (phylloquinones, menaquinones)

Vitamin E (tocopherols

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Asam folat

• Penting untuk biosintesis

• Fungsi : Tetrahidrofolat (folat tereduksi) menerima satu bagian karbon dari donor (serine, glycine, and histidine) dan memindahkannya keperantara dalam sintesis asam amino, purin, danthymidine mono phosphate (TMP)

• Kurang asam folat sering terjadi karena– Kebutuhan meningkat (ibu hamil dan menyusui)

– Gangguan absorbsi ( alkoholik, penyakit usus halus, obat obatan)

• Dampak kekurangan folat:

– Anemia megaloblastik : Gangguanpembentukan purin dan TMP gagal replikasi DNA sel gagalmembelah

– Kerusakan “ neural tube” padajanin ( spina bifida dan anensefali)

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KOBALAMIN (VITAMIN B12)

• Fungsi : Koenzim reaksi degradasiasam amino dan asam lemak

• Sumber : hati, susu, kerang, telur, daging, ayam

• Kekurangan Vit B12:

– gangguan syaraf : degradasi lemakterganggu akumulasilemakmenempel di membran sel, termasuk sel syaraf

– Anemia perniciosa

ASAM ASKORBAT (VITAMIN C)

• Fungsi : • agen pereduksi beberapa reaksi• Koenzim hidroksilasi : hidroksilasi

prolil dan lisil pada pembentukankolagen

• Mempertahankan jaringan ikat: perluuntuk penyembuhan luka

• Membantu penyerapan besi• Antioksidan

• Sumber : buah buahan, lemon, Jeruk, stroberi,jambu , dan sayur sayuran

• Kekurangan Vit C:– Scurvy : gusi berongga dan gigi tanggal,

mudah berdarah, sendi bengkak, anemia

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Vitamin A

• Retinoid adalah molekul yang berhubungan dengan retinol (vitamin A), penting untuk pengelihatan, reproduksi, pertumbuhan, dan menjagajaringan epitel.

• Sumber : hati, ginjal, cream, butter, dantelur. Sayuran kuning dan hijau gelap sumber karoten

• Kebutuhan : dewasa 900 retinol activity equivalents (RAE) (lk) dan 700 RAE (pr) (1 RAE = 1 mg retinol, 12 mg β-carotene, atau 24 mg carotenoid)

• Sumber : hewani dannabati

• Dibawakilomikrondari usus dandisimpandihati danadiposa

• Dibutuhkandi sel danretina

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Kegunaan vitamin A

Vitamin D

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Vitamin D

• Kelompok sterol, punya fungsi seperti hormon• Fungsi :

– Pada usus : 1,25-diOH-D3 merangsang penyerapankalsium dan phosphate.

– Pada tulang : 1,25-diOH-D3 merangsang mobilisasicalcium dan phosphate mempertahankan kadarkalsium dan fosfat darah

• Sumber– Diet: Ergocalciferol (vitamin D2), nabati, dan

cholecalciferol (vitamin D3), dari hewani– Prekursor vitamin Endogen: 7-Dehydrocholesterol

(pada kulit, butuh sinar matahari)

• Kekurangan vit D kehilangan mineral tulang, ricketsia (anak), osteomalasia (dewasa)

Vitamin k

• Berperan pada pembekuandarah (koenzim reaksikarboksilasi asam glutamat)

• Fungsi– Pembetukan γ-

carboxyglutamate (Gla): untuk pembentukanprothrombin dan blood clotting factors II, VII, IX, and X.

– Interaksi prothrombindengan platelets:

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Vitamin E

Bentuk paling aktif adalah α-tocopherol

Fungsi utama vitamin E adalah sebagaiantioksidan

Sumber vitamin EMinyak sayur sayuran, , hati dan telurkebutuhan harian α-tocopherol 15 mg

Defisiensi vitamin ETerjadi pada bayi prematur dan gangguanabsorbsi lipid (pada dewasa). Menyebabkan Gangguan sel darah merah danmembran sel.

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MINERAL

Tubuh mengandung (dalam % berat) :

• Oksigen 6 5 %

• Karbon 18%

• Hidrogen 10%

• Nitrogen 3 %

• Kalsium 1, 5 %

• Fosfor 1 %

• Elemen lain 1, 5 % (K,Na,Cl,dls)

Elemen/mineral yang penting untuk tubuh antara lain :

K,Na,Cl,Ca,P,Fe,I,F,Co.

Berdasarkan atas kebutuhannyaperhari,mineral dibagi atas :

• MAKRO (major) MINERALDibutuhkan lebih dari 100mg/hari.Contoh : Ca,P,Na,K,Cl,Mg.

• MIKRO (trace) MINERALDibutuhkan kurang dari 100mg/hari.Contoh :

Cr,Co,Cu,I,Fe,Mn,Mo,Se,Si,Zn,F.

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KALSIUM (Ca)

• Merupakan unsur padatulang dan gigi.

• Turut mengatur fungsisyaraf dan otot.

• Penting pula untukmetabolisme sel

• Absorpsinyamembutuhkan “Calcium Binding Protein”,dikontrololeh vit D, Parathormon, Calcitonin,dls.

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FOSFOR (P) : Merupakan unsur pada tulang, gigi, ATP, asamnukleat. Absorpsinya dikontrol Vit.D

Functions• Component of bones/teeth

80% in bone (hydroxyapatite)20% in soft tissue

Membrane phospholipids, DNA, RNA• Similar to calcium• Vitally important in energy metabolism

ATP and creatine phosphateSugar phosphates

• Acid-base balance (HPO4–)

• Regulation of metabolismGlucose-6-phosphatePhosphorylation activates or inactivates enzymes

NATRIUM : Kation utama dalam cairan ekstra sel.Mengatur volume plasma.Mengatur keseimbangan asam- basaMengatur fungsi syaraf dan otot.Aktivator untuk enzim Na+ / K+ -ATP ASE.

KLORIDA

• Mengatur balans cairan tubuh danelektrolit.

• Unsur cairan dan getah lambung.

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Sodium (Na) and Chloride (Cl)

Functions Electrolytes Absorption of glucose and amino acids Transmission of nerve impulses

Action potential

Osmotic pressure balance 10% sodium and chloride intracellular, 90%

extracellular Sodium is main extracellular cation

Maintained by Na/K ATPase

Chloride is main extracellular anion

HCl and chloride salts in gastric secretions

Sodium and Chloride

Blood concentrations highly regulated Excess intake = increased excretion Little danger of toxicity if water available

NaCl added to diets to increase palatability Causes of deficiencies:

Lactation Sodium and chloride secreted in milk

Rapid growth On a diet of cereals or forages

High temperatures or hard work Sweat

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Sodium, SerumAdults: 136-145 mEq/L Sodium is the major cation in extracellular space Intracellular sodium is approximately 5mEq/L…. Aldosterone and antidiuretic hormone help regulate sodium

balanceSymptoms of hypernatremia: Dehydration thirst, agitation, restlessness, hyper-reflexes and

seizures.Symptoms of hyponatremia Muscle cramps, muscle twitching, headache, dizziness, lethargy,

confusion, convulsions, stupor and coma. The changes in the central nervous system are due to fluid shifts from the extracellular spaces to the intracellular spaces, causing cells to swell.

Elevated blood glucose levels give falsely low serum sodium values. Use this formula to correct serum sodium values. Na= glucose x 2 + Na

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Chloride, Cont’d

Overhydration

Congestive heart failure

Vomiting

Addison’s disease

Hypokalemia

Hyponatremia

Diuretic therapy

Metabolic alkalosis

Burns

Emphysema

Dehydration

Excessive infusion of saline

Cushing’s syndrome

Eclampsia

Anemia

Hypernatremia

Multiple myeloma

Metabolic acidosis

Hyperventilation

Decreased byChloride Increased by

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KALIUM/POTASSIUM

Kation utama dalam cairan intra sel.

Mengatur fungsi syaraf dan otot.

Aktivator untuk enzim Na+ /K+ -ATP ASE.

Potassium

Functions: Third-most abundant mineral in the body

2/3 of whole-body potassium content in skin and muscles

>95% of potassium intracellular (major intracellular cation) Maintained by Na/K ATPase

Regulation of osmotic and acid-base balance

Transmission of nerve impulses Potassium is the major determinant of the resting membrane

potential of all cells

Cofactor for several reactions in carbohydrate metabolism

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Potassium, serumAdults: 3.5 - 5.0 mEq/L

Potassium is the principle intracellular cation.

The normal potassium levels within cells is approximately 150 mEq/L compared to 3.5 - 5.0 mEq/L in serum

The serum potassium concentration is related to renin-aldosterone mechanism, sodium reabsorption and acid-base balance.

When acid-base balance is altered the serum potassium also changes. As the pH of the blood increases (becomes more alkalotic) the potassium shifts from the serum to the cells. As the pH of the blood decreases (becomes more acidic) the intracellular potassium shifts to the serum.

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Potassium, serum cont’d

Symptoms of hypokalemia:

Muscle weakness, cramps, hyporeflexia, paresthesias, decreased bowel motility, hypotension, cardiac arrhythmia, drowsiness, lethargy and coma. Serum potassium below 3.5 mEq/L is often seen with a serum pH above 7.45, decreased serum bicarbonate level and possibly elevated blood glucose.

Symptoms of hyperkalemia:

include confusion, irritability, nausea, vomiting, intestinal colic, paresthesia abdominal cramps and muscle paralysis.

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Magnesium (Mg)

Functions Bone formation

~60% in bone

Enzyme activation Carbohydrate, lipid metabolism

7 enzymes in glycolysis require magnesium as a cofactor

Urea cycle

Binds mRNA to ribosomes

Associated with ATP metabolism ATP–Mg2+ complex

Unsur pada tulang dan gigi.Kofaktor untuk enzim kinase

Magnesium and Muscle Function

Magnesium required for energy releasing enzyme activity in skeletal muscle ATP needed for detachment and calcium

uptake

Calcium is the link between excitation and contraction Lack of ATP to return calcium to storage

results in tetany

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Magnesium

Deficiency Vasodilation

Results in reduced blood pressure

Hyperirritability, convulsions

Anorexia, reduced weight gain

Hyperemia

Hypomagnesemic tetany (grass tetany) Early lactating cows on grass

Poor nervous and muscular control

Usually not an issue, adequate levels present in most diets

Magnesium Deficiency –Grass Tetany

Also called grass staggers, hypomagnesemia Low blood magnesium

Symptoms Nervousness

Tremors, twitching of face muscles

Staggering gait or convulsions

Etiology not completely understood

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KOBALTUnsur pada vitamin B12

TEMBAGA (Cu)

Unsur pada enzim oksidase.

Berperan pada absorpsi Fe.

JODIUM

Unsur pada hormon T3 dan T4

BESI

Unsur pada enzim-enzim yang mengandung Heme (misal :

hemoglobin, Sitokrom,dls.)

MOLIBDENUM (Mo)

Unsur pada enzim-enzim oksidase

MANGAN (Mn)

Kofaktor untuk enzim Hidrolase, Dekarboksilase,Transferase.

Berperan pada sintesis Glikoprotein & Proteoglikan.

SELENIUM (Se)

Unsur pada Glutathion Peroksidase.

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SILIKON (Si)

Berperan pada kalsifikasi tulang.

SENG (Zn)

Kofaktor untuk enzim LDH, Alkalifosfatase,Karbonik

anhidrase, dls.

FLUORIDA (F)

Meningkatkan pengerasan tulang dan gigi.