Vitamins Shahd AlAli

Water soluble vitamins Fat soluble vitamins

Absorbed directly from the gut to the bloodstream

Dissolved in dietary fats to lymphatic system and then bloodstream and bind to protein carrier

Less likely to be toxic = excreted in urine

Stored in adipose tissues *can be toxic

Vitamin B, Biotin, Folic acid, Vitamin C

K A D E

Organic component required as cofactor or anabolism or catabolism

Vitamin B1 Thiamine Fount in grains, meats It’s a coenzyme for CHO metabolism The active form is thiamine pyrophosphate TPP (ATP transfer to thiamine)

TTP is used as a coenzyme for Transketolation reactions in PPP ) Conversion of pyruvate to acetyl-CoA (PDH)Thaimine deficiney is most commonly caused due to chronic alcoholism What if thiamine levels were low? 1. Decrease the amounts of acetyl-CoA to enter TCA cycle and increase

amounts of pyruvate available for anaerobic oxidation so more lactic acid

Paresthesias

Beriberi (wet/dry) Wet: involves the cardiovascular system & neuropathy

Dry beriberi: affect both peripheral nerves (motor and sensory neuropathies)

Wernicke-Korsakoff syndrome occurs in chronic alcoholics with B1 deficiency triad

Wernicke’s encephalopathy: 1.Ophthalmoplegia 2.Truncal ataxia3.Confusion

Untreated encephalopathy progress to Korsakoff’s syndrome impaired short memory

Vitamin B6- Pyridoxine A pyridine derivative Found in wheat, egg yolk and meats Its responsible for the conversion transamination, deamination and

creating the enzymes of liver AST and ALT Deficiency of vitamin B6 can result in convulsion and hyperirritability Decreased concentration of vitamin B6 may occur after the used of Oral contraceptives, isoniazid, penicillamine Vitamin B6 excess causes sensory neuropathy

Vitamin B12- Cobalamin Animal products are the only source of vitamin B12 Can be stored in the body for up to 3 years Required IF for absorption in the distal 3rd of ileum Vitamin B12 dependent enzymes Methionine synthase , Methylmalonyl-CoA mutase (TCA)Causes of deficiency:

pernicious anemia Gastroectomy Infections H.pylori Pancreatic insufficiency

Folate circulates as methyl-THF removal of methyl group allows the participation in synthesis of DNA precursors

1. Methyl group is transferred to vitamin B12 2. Vitamin B12 then transfer it to homocysteine > methionine Increased serum homocysteine (increased risk of thrombosis)

Vitamin B12 is a cofactor for the conversion of methylmalonic acid to succinyl CoA (imp for FA metabolism) Deficiency of vitamin B12 results in increased levels of methylmalonic acid which impairs spinal cord myelination.

Methylmalonyl-CoA mutase

Methionine synthase

Clinical Signs of Vitamin B12 deficiency Neuropathy charactirized by defective myelin formation and subacute

degeneration of dorsal and lateral spinal columns. Poor proprioception and vibratory sensation (posterior column) and spastic paresis (lateral)

Vitamin A

i. Retinoids of animal origin ii. Carotenoids, found in plants Vit. A deficiency cause: blindness, increased susceptibility to

infectious diseases Vit. A excess causes: tissue damage, toxicity of CNS

(headache, nausea, ataxia, and anorexia, increased CSF pressure), also affects the liver, bones and skin

Summary Vitamin Deficiency Excess Vitamin B1 Wet beriberi :

cardiovascular Dry beriberi: Wernicke’s encaphylopathy

1. Ophthalmoplegia 2. Truncal ataxia3. Confusion

Korsakoff’s syndrome: impaired short memory

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Vitamin B6 Convulsion and hyperirritability

Sensory neuropathy

Vitamin B12 Subacute combined degeneration of spinal cord (poor proprioception and vibratory sensation)

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Vitamin A Blindness tissue damage, toxicity of CNS (headache, nausea, ataxia, and anorexia, increased CSF pressure