VITAMINS

• What are vitamins?


  Organic compounds that cannot be synthesized by the body
• Why do we need to obtain vitamins from our diet?


  Because the body cannot synthesize them
• What happens when there is an absence of vitamins in the diet?


  It leads to deficiency states or specific diseases
• What role do vitamins play in enzymatic reactions?


  They act as cofactors
• What are the two major classes of vitamins?

  • Water soluble vitamins
  • Fat soluble vitamins
• Which vitamins are classified as water soluble?

  The B group and Vitamin C
• What is a characteristic of water soluble vitamins?


  They are polar and hydrophilic
• How are excess water soluble vitamins handled by the body?


  They are excreted in urine
• Which vitamins are classified as fat soluble?

  Vitamins A, D, E, and K
• What is required for the absorption of fat soluble vitamins?

  Fat
• Where are fat soluble vitamins stored in the body?


  In the liver
• What can happen if fat soluble vitamins are consumed in excess?


  They can become toxic
• What are the categories of water soluble vitamins?


  • Energy-releasing vitamins
  • Hematopoietic vitamins
• What is the active form of Vitamin B1 (Thiamine)?


  Thiamine pyrophosphate
• What are the key enzymes that require thiamine pyrophosphate as a cofactor?


  Pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, branched chain amino acid α-ketoacid dehydrogenase, transketolase
• What are the consequences of decreased activity of pyruvate dehydrogenase?


  Accumulation of pyruvate and lactate, decreased acetyl CoA and ATP formation
• What is the result of decreased activity in the pentose phosphate pathway due to thiamine deficiency?


  Low levels of NADPH necessary for fatty acid synthesis
• What is the structure of Vitamin B1 (Thiamine)?


  Contains a pyrimidine and a thiazole nucleus coupled by a methylene bridge
• How is thiamine converted to its active form?


  By thiamine diphosphokinase in the liver and brain
• What are the pharmacological actions of thiamine at therapeutic doses?


  No pharmacodynamic actions
• How is thiamine absorbed in the body?


  By Na+ - dependent active transport
• What diseases can thiamine treat or prevent?


  Beri-beri, Wernicke’s encephalopathy, Korsakoff’s syndrome, alcoholic polyneuropathy, neuritis of pregnancy
• What are the active forms of Vitamin B2 (Riboflavin)?


  Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)
• What are the functions of FAD and FMN?


  They are coenzymes for oxidases and dehydrogenases
• What are the symptoms of riboflavin deficiency?


  Angular stomatitis, cheilosis, cataracts, glossitis
• What is the absorption and excretion process of riboflavin?


  Absorbed readily from the GIT and distributed to all tissues
• What is the primary therapeutic use of riboflavin?


  Treatment or prevention of riboflavin deficiency
• What is Vitamin B3 also known as?


  Niacin
• What is the role of NAD+ and NADP+ in the body?


  They are coenzymes for many dehydrogenases in redox reactions
• What condition is caused by niacin deficiency?


  Pellagra
• What are the symptoms of pellagra?


  Dermatitis, diarrhea, dementia
• What are the pharmacological effects of nicotinic acid?


  Flushing, pruritus, gastrointestinal distress, hepatotoxicity
• How are nicotinic acid and nicotinamide absorbed?


  Readily from all portions of the intestinal tract
• What are the therapeutic uses of niacin?


  Prophylaxis and treatment of pellagra, Hartnup’s disease, carcinoid tumors
• What is the function of Pantothenic acid?

  Involved in the transfer of acyl groups as coenzyme A
• What is a rare condition caused by Pantothenic acid deficiency?


  Burning foot syndrome
• What are the sources of Pantothenic acid?


  Grain cereals, legumes, animal tissues
• What is the pharmacological action of Pantothenic acid?


  No pharmacological actions even when administered in large doses
• What are the key metabolic pathways involving coenzymes formed from water-soluble vitamins?

  • Energy metabolism
  • Fatty acid synthesis
  • Amino acid metabolism
• What are the common food sources of water-soluble vitamins?


  • Fruits
  • Vegetables
  • Whole grains
  • Dairy products
  • Meat