Water Soluble Vitamins Quiz

Water Soluble Vitamins

• Thiamine (Vitamin B1)
  • Function: Acts as a coenzyme in carbohydrate metabolism and branched-chain amino acid metabolism.
  • Absorption & Excretion: Absorbed in the small intestine, excreted in urine.
  • Deficiency: Causes beriberi, often due to decreased intake or absorption, especially in chronic alcoholism. Symptoms include neurological problems.
  • RDA: 1.2 mg/day (males), 1.1 mg/day (females)
  • Best Indicator: Erythrocyte transketolase (ETK) activity; a 25% increase after thiamine pyrophosphate (TPP) suggests deficiency.
• Riboflavin (Vitamin B2)
  • Function: Component of coenzymes FAD and FMN, involved in oxidation-reduction reactions.
  • Absorption & Excretion: Absorbed in the small intestine, excess excreted in urine.
  • Sources: Milk, liver, eggs, meat, leafy vegetables.
  • Deficiency: Can be caused by alcoholism, chronic diarrhea, malabsorption, and certain drug interactions.
  • RDA: 1.3 mg/day (males), 1.1 mg/day (females)
  • Best Indicator: Reduced glutathione reductase activity >40%.
• Pyridoxine (Vitamin B6)
  • Function: Exists as pyridoxine, pyridoxal, and pyridoxamine; part of coenzymes important for metabolism.
  • Sources: Meat, poultry, fish, potatoes, vegetables, dairy, grains,
  • Deficiency: Rare but possible in uremia, liver disease, malabsorption, malignancies, and chronic alcoholism. Symptoms can include neurological deficits.
  • RDA: 1.3-1.7 mg/day (males), 1.3-1.5 mg/day (females)
  • Toxicity: High doses may cause peripheral neuropathy.
  • Best Indicator: Linked to hyperhomocystinemia
• Niacin (Vitamin B3)
  • Function: Part of NAD and NADP coenzymes, essential for metabolism, glycolysis, and lipid metabolism.
  • Sources:Derived from dietary tryptophan; exists as nicotinic acid and nicotinamide. Found in many foods: animal, plants, grains.
  • Absorption & Excretion: Absorbed in the small intestine; excess is excreted in urine.
  • Deficiency: Causes pellagra, characterized by diarrhea, dementia, dermatitis, and death. Frequently seen in alcoholism.

Folate (Vitamin B9)

• Function: Acts as a coenzyme in one-carbon transfer reactions.
• Relation to Vitamin B12: Closely related; deficiency in either can cause megaloblastic anemia.
• Sources: Green leafy vegetables, fruits, organ meats, yeast.
• Cooking: Cooking with water destroys folate.
• Increased Requirements: Pregnancy, lactation, hemolytic anemia, iron deficiency, prematurity, dialysis.
• Deficiency Indicators: Low serum folate, hypersegmented neutrophils, high urinary formiminoglutamic acid (FIGLU), low erythrocyte folate.
• Drugs Affecting Folate: Anticonvulsants, methotrexate, sulfasalazine, isoniazid.
• Toxicity: No known toxicity.
• RDA: 400 µg/day (higher in pregnancy)
• Reference Ranges: Serum: 3–16 ng/mL, Erythrocyte: 130–630 ng/mL, Deficient: <140 ng/mL.

Vitamin B12 (Cobalamin)

• Function: Part of coenzymes essential for hematopoiesis and fatty acid metabolism; plays a role in DNA synthesis and neurological function.
• Absorption & Excretion: Absorbed in the ileum with intrinsic factor from the stomach
• Coenzyme Functions: Coenzyme in hematopoiesis, fatty acid metabolism.
• Sources: Animal products (meat, eggs, milk)
• Deficiency: Common in the elderly, strict vegetarians, those with malabsorption disorders. Leads to megaloblastic anemia (pernicious anemia) and neurological disorders.
• Deficiency Effects: Leads to megaloblastic anemia and neurological disorders.
• Pernicious Anemia: Linked to intrinsic factor antibodies, parietal cell antibodies.
• Diagnostic Tests: Schilling test, serum B₁₂ levels, methylmalonic acid tests help confirm deficiency.

Biotin

• Function: Essential coenzyme for carboxyl transfer reactions. Involved in gluconeogenesis, lipogenesis, and fatty acid synthesis. Found in many foods.
• Sources: Synthesized by gut bacteria.
• Deficiency: Can be caused by raw egg ingestion (raw eggs contain avidin which binds biotin). Also found in long-term parenteral nutrition and enzyme defects.
• RDA: 30 µg/day

Pantothenic Acid (Vitamin B5)

• Function: Component of coenzyme A; essential for acyl group transfer reactions.
• Sources: Present in animal and plant tissues (milk, eggs, whole grains, liver)
• Conversion: Converted to coenzyme A.
• Deficiency: Rare, but can be indicated by low blood pantothenate (<100 µg/dL) and low urinary excretion (<1 mg/day)
• RDA: 5 mg/day

Vitamin C (Ascorbic Acid)

• Function: Strong reducing agent; important for collagen formation, iron absorption, and catecholamine synthesis.
• Sources: Found in fruits (citrus) and vegetables.
• Deficiency: Leads to scurvy (bleeding gums, impaired wound healing, anemia).
• Excess Intake: May interfere with vitamin B12 metabolism and drug actions.
• RDA: 90 mg/day (males), 75 mg/day (females)

Carnitine

• Function: Conditionally essential nutrient involved in fatty acid metabolism.

Other

• General information: Deficiency of certain vitamins can be hereditary or acquired, with pregnancy, valproic acid, dialysis, or strict vegan diets being possible causes of deficiency.