vitamins by harshit at semina hall

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Nutrients : 

Nutrients Carbohydrates Fats Proteins Vitamins Minerals Water

Vitamins : 

Vitamins The word "vitamin" comes from vita, the Latin for "life“ Everybody must eat a certain amount of vitamins to stay healthy Vitamins are chemicals found in very small amounts in many different foods. Tiny quantities are enough for the needs of the body If people live on a very limited range of foods they may not get their proper share of vitamins

Classification of Vitamins : 

Classification of Vitamins Vitamins, of which there are 14, are classified into two main groups: Water soluble and Fat soluble Fat soluble – stored in bodies fat tissue A, D, E & K Water soluble – not stored in the body B vitamins, folic acid & vitamin C



Vitamin C - Ascorbic Acid : 

Vitamin C - Ascorbic Acid Structure Metabolism oxidation/reduction dehydroascorbic acid dehydroascorbate reductase glutathione (GSH) glutamate-cysteine-glycine

Vitamin-C(Ascorbic acid) : 

Vitamin-C(Ascorbic acid) Vitamin C - helps to maintain skin integrity, absorb iron from the gut and heal wounds, and is important in immune functions Dietary sources: Vitamin C is found in citrus fruit and juices, tomatoes, spinach, potatoes, berries, green and red peppers, and broccoli

Functions of Vitamin C : 

Functions of Vitamin C Enhances absorption of iron reduces iron to more absorbable ferrous form chelates with ferrous ion to make it more soluble

Functions of Vitamin C : 

Functions of Vitamin C Hydroxylation of proline and lysine post-translational reaction of procollagen hydroxylated collagen can be cross-linked to triple helix collagen Scurvy - weak collagen

Functions of Vitamin C : 

Functions of Vitamin C Hydroxylation Reactions Involves O2 and metal coenzyme (ferrous, cuprous) Carnitine synthesis Tyrosine synthesis & catabolism

Functions of Vitamin C : 

Functions of Vitamin C Hydroxylation Reactions Synthesis of Neurotransmitters Dopamine Norepinephrine Serotonin Bile acid synthesis

Functions of Vitamin C : 

Functions of Vitamin C Antioxidant Activity Reacts and removes active oxygen species Pro-oxidant Activity Reduces metals to their pro-oxidant forms

Scurvy : 

Scurvy Bleeding gums petechiae easy bruising impaired wound healing and bone repair joint pain anemia

RDA for Vitamin C : 

RDA for Vitamin C 10 mg/day prevents scurvy historic RDA’s 45-70 mg (60mg in 1989), 75mg in 2000 prevention of scurvy vs antioxidant effect with supplements?

Toxicity of Vitamin C : 

Toxicity of Vitamin C UL adults: 2000mg/d Osmotic diarrhea Oxalate kidney stones Decreases uric acid reabsorption resulting in increased risk of gout Affects diagnostic tests in feces and gout fecal blood urinary glucose



Thiamin- B1 : 

Thiamin- B1 Structure pyrimidine ring thiazole ring methyl bridge

Slide 22: 

Thiamin : vitamin form Thiamin pyrophosphate: coenzyme form Pyrimidine ring Thiazole ring

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Dietary sources: cereals, pulses, oil seeds, nuts and yeast are goods sources. In animal food like pork, liver, heart, kidney, milk etc. RECOMMENDED DIETARY ALLOWANCE: Adults: 1-1.5 mg/day. Children: 0.7-1.2 mg/day.

Biochemical Functions of B-1 : 

Biochemical Functions of B-1 Oxidative Decarboxyation Reactions Pyruvate Dehydrogenase Pyr+CoA+NAD --> AcCoA+CO2 +NADH a-keto-glutarate dehydrogenase aKG+CoA+NAD-->SuccCoA + CO2+NADH important in CHO/energy metabolism

Biochemical Functions of B-1 : 

Biochemical Functions of B-1 Transketolation HMP pathway Peripheral Nerve Function TPP or TPPP non-cofactor function mechanism?

Thiamin Deficiency : 

Thiamin Deficiency Beri-Beri anorexia, fatigue, depression effects on cardiovascular system nervous system

Infantile Beri-Beri : 

Infantile Beri-Beri first 6 months breast milk deficient in B-1 mother w/o symptoms rapid onset cyanosis, tachycardia, labored breathing heart failure and death

Wet Beri Beri : 

Wet Beri Beri symptoms similar to congestive heart failure Pitting edema - trunk, limbs, face labored breathing, tachycardia rapid deterioration fatal cirulatory collapse responds rapidly to B-1 supplements

Dry Beri-Beri : 

Dry Beri-Beri no edema progressive wasting numbing and weakening of extremities chronic infections

Assessment of Thiamin Status : 

Assessment of Thiamin Status Urinary thiamin excretion Blood or serum thiamin concentration [pyr + lac] in blood erythrocyte transketolase activity stimulation with B-1


RIBOFLAVIN-B2 Structure: 6,7 dimethyl isoalloxazine + D-ribitol. Attached by nitrogen atom.

Niacin : 

Niacin Structure Nicotinic Acid = Niacin Nicotinamide = Niacinamide

Cofactor Forms of Niacin : 

Cofactor Forms of Niacin Nicotinamide Adenine Dinucleotide NAD nicotinamide-ribose-PP-ribose-adenine Nicotinamide Adenine Dinucleotide Phosphate NADP nicotinamide-ribose-PP-(ribose-P)-adenine

Slide 40: 

Nicotinic Acid (Plant form) Nicotinamide (animal form) (reduced form)

Slide 41: 

Nicotinamide Adenine Dinucleotide nicotinamide adenine If Phosphate here -> NADP

Biochemical Functions of B-3 : 

Biochemical Functions of B-3 Oxidation-Reduction Reactions (NAD/NADH Dehydrogenases Electron Transport System Involved in energy production

Biochemical Functions of B-3 : 

Biochemical Functions of B-3 Synthetic Pathways (NADPH) FA synthesis Cholesterol synthesis NEAA synthesis Purine & Pyrimidine synthesis

Deficiency of B-3 : 

Deficiency of B-3 Pellegra Dermatitis scaly dermatitis, sun exposed Dementia confused, disoriented Diarrhea irritation/inflammation of mucous membranes

Assessment of B-3 Status : 

Assessment of B-3 Status Urinary excretion of niacin metabolites N-methyl nicotinamide 2-pyridone

Vitamin B-12 : 

Vitamin B-12 Structure cobalamine methyl cobalamine transport and coenzyme form adenosyl cobalamine storage and coenzyme form

Dietary Sources : 

Dietary Sources Animal products including milk and eggs GI microorganisms Vegan sources N-fixing legumes fortified grains vitamin supplements

Digestion & Absorption of B12 : 

Digestion & Absorption of B12 Intrinsic Factor gastric glycoprotein binds with B12 in small intestine IF-B12 complex binds to B12receptor in ileum for absorption B12 absorption requires functioning stomach, pancreas, and ileum

Causes of B-12 Deficiency : 

Causes of B-12 Deficiency Inadequate intake - rare DRI adults 2.4 ug/d Usual intake 7-30 ug/d Malabsorption of B-12 IF deficiency other GI tract problems

Functions of B12 : 

Functions of B12 Homocysteine to Methionine methionine synthetase requires 5-methyl THF deficiency of B12 results in “methyl-trap” of folate results in megaloblastic anemia synergistic effect of B12 and folate

Functions of B12 : 

Functions of B12 Mutases methyl malonyl CoA mutase proprionyl-CoA ->->succinyl-CoA accumulation of methyl-malonate may inhibit AcetylCoA carboxylase

B-12 Deficiency : 

B-12 Deficiency Pernicious anemia megaloblastic anemia Methyl-folate trap Delayed or failure of normal cell division due to impaired DNA synthesis neuropathy defective myelination progressive peripheral weakening unresponsive to folate upper limit to folate supplementation/enrichment

Folic Acid / Folacin : 

Folic Acid / Folacin Structure pteridine ring - PABA - glutamate Stability very sensitive to heat easily oxidized leached

Slide 58: 

RDA : 200 microgram/day. During pregnance:400 microgram/day

Folate Functions : 

Folate Functions Single carbon metabolism

Folate Functions : 

Folate Functions Interconversion of serine and glycine ser + THF <---> gly + 5,10-Me-THF Degradation of histidine his->->->formiminoglutamate(FIGLU) FIGLU+THF -> glu + 5-forminino-THF histidine load test Functional test for folate status

Folate Functions : 

Folate Functions Purine and Pyrimidine Synthesis dUMP + 5,10-Me-THF -> dTMP + THF Methionine Synthesis homocysteine + 5-Me-THF -> MET + THF MET as a methyl donor for choline synthesis

Folate Deficiency : 

Folate Deficiency Megaloblastic Anemia decreased DNA synthesis failure of bone marrow cells to divide normal protein synthesis results in large immature RBC’s contrast with microcytic hypochromic anemia

Folate Deficiency : 

Folate Deficiency Homocysteine Coronary Heart Disease risk factor ? genetic homocystinuria - premature CHD hi [homocys] related to hi CHD risk lo [folate, B-12, B-6] related to hi CHD risk lo intake of B-vit related to hi CHD risk

Folate and CHD : 

Folate and CHD Nurse’s Health Study (JAMA 1998) 80,000 nurses, 14 yr follow-up Relative Risk - highest vs lowest quintile RR = 0.69 for folate RR = 0.67 for B-6 RR = 0.55 for folate + B-6

Folate and Neural Tube Defects : 

Folate and Neural Tube Defects Defects in formation of neural tube (brain & spinal cord) First two months gestation Anencephaly absence of cerebral hemispheres

Folate and Neural Tube Defects : 

Folate and Neural Tube Defects Spina bifida defective closure of vertebral column spinal cord protrusion from spinal column results in damage to spinal cord lower limb and hip paralysis rectal and bladder problems

Names and RolesVitamins : 

Names and RolesVitamins

Deficiencies and SourcesVitamins : 

Deficiencies and SourcesVitamins

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