Vitamins And Minerals Exam Terms

Vitamin A

Transporters: Chylomicrons → liver → retinol-binding protein (RBP), transthyretin (TTR)

Vitamin A

Enzymes: lecithin retinol acyltransferase (LRAT), retinyl ester hydrolase

Vitamin A

Deficiency: xerophthalmia, night blindness, Bitot’s spots, infection risk ↑

Vitamin A

Case clue: vision issues, dry eyes, poor mucosal immunity

Vitamin A

Toxicity: Hypervitaminosis A (↑ ICP, liver damage), teratogenicity (e.g., Accutane)

Vitamin A

Misc: RAE conversion (12 mg β-carotene = 1 mg RAE); RDA: 0.9 mg (M), 0.7 mg (F)

Vitamin B12

Transporters: Intrinsic factor, Cubilin receptor (ileum), Transcobalamin II

Vitamin B12

Enzymes: methionine synthase, methylmalonyl-CoA mutase

Vitamin B12

Deficiency: pernicious anemia, megaloblastic anemia, neurological damage

Vitamin B12

Case clue: numbness, tingling, anemia, gastric surgery or low IF

Vitamin B12

Misc: Enterohepatic recycling; RDA ≈ 2 µg/day; mostly from animal products

Folate

Transporters: proton-coupled folate transporter (PCFT), conjugase enzymes

Folate

Enzymes: One-carbon transfer reactions (nucleic acid synthesis)

Folate

Deficiency: Megaloblastic anemia, ↑ homocysteine, neural tube defects

Folate

Case clue: anemia, pregnancy, poor diet

Folate

Toxicity: masks B12 deficiency

Folate

Misc: RDA = 400 µg/day; leafy greens, fortified grains

Pantothenic Acid

Transporters: shared multivitamin transporter (SMVT)

Pantothenic Acid

Enzymes: coenzyme A synthesis

Pantothenic Acid

Deficiency: Burning foot syndrome (rare)

Pantothenic Acid

Case clue: alcoholic, neuropathic pain in feet

Pantothenic Acid

Toxicity: Diarrhea at high doses

Biotin

• Transporters: SMVT

• Enzymes: Carboxylases (fatty acid synthesis, gluconeogenesis)

Biotin

Deficiency: Dermatitis, nausea, TPN patients, biotinidase deficiency

Biotin

Misc: AI = 30 µg/day; liver, egg yolk

Vitamin B6 (Pyridoxine)

Transporters: Passive diffusion (jejunum)

Vitamin B6 (Pyridoxine)

Enzymes: aspartate aminotransferase (AST), alanine aminotransferase (ALT), decarboxylases (serotonin, dopamine, histamine)

Vitamin B6 (Pyridoxine)

Deficiency: Cheilosis, glossitis, microcytic anemia, neuropathy, seizures in infants

Vitamin B6 (Pyridoxine)

Case clue: alcoholism, isoniazid use, elderly

Vitamin B6 (Pyridoxine)

Toxicity: Sensory neuropathy (>100 mg/day)

Vitamin C

Transporters: SVCT1, SVCT2, GLUT (dehydroascorbate)

Vitamin C

Enzymes: prolyl hydroxylase, lysyl hydroxylase, dopamine β-monooxygenase (collagen, carnitine, neurotransmitters)

Vitamin C

Deficiency: scurvy (bleeding gums, bruising, poor wound healing, fatigue)

Vitamin C

Case clue: Sailor, poor diet, gum bleeding, delayed healing

Vitamin C

Toxicity: GI upset, oxalate kidney stones (high doses)

Vitamin C

Misc: Antioxidant, ↑ iron absorption, humans can’t synthesize it