Clinical Nutritionist CCN Micronutrients and Deficiencies 2 — Questions and Answers
Question 1: Which B vitamin acts as a coenzyme in over 100 enzymatic reactions, particularly amino acid metabolism?
- Pyridoxine (vitamin B6) (Correct answer)
- Riboflavin (vitamin B2)
- Thiamine (vitamin B1)
- Niacin (vitamin B3)
Correct answer: Pyridoxine (vitamin B6)
Vitamin B6 as pyridoxal phosphate (PLP) is a cofactor for aminotransferases, decarboxylases, and other enzymes central to amino acid metabolism.
Question 2: Zinc deficiency is characteristically associated with which clinical finding?
- Impaired taste and smell (hypogeusia/anosmia) (Correct answer)
- Scurvy
- Pellagra
- Wernicke's encephalopathy
Correct answer: Impaired taste and smell (hypogeusia/anosmia)
Zinc deficiency causes hypogeusia (reduced taste acuity), anosmia, poor wound healing, growth retardation, and immune dysfunction.
Question 3: What is the Tolerable Upper Intake Level (UL) for preformed vitamin A (retinol) in adults?
- 3,000 mcg RAE/day (Correct answer)
- 10,000 mcg RAE/day
- 900 mcg RAE/day
- 5,000 mcg RAE/day
Correct answer: 3,000 mcg RAE/day
The UL for preformed vitamin A is 3,000 mcg RAE/day for adults; excess intake causes hypervitaminosis A with symptoms including liver toxicity and teratogenicity.
Question 4: Selenium functions primarily as a component of which enzyme system that protects against oxidative stress?
- Glutathione peroxidase (Correct answer)
- Superoxide dismutase
- Catalase
- Thioredoxin reductase
Correct answer: Glutathione peroxidase
Selenium is an essential component of glutathione peroxidases (GPx), selenoenzymes that reduce hydrogen peroxide and lipid hydroperoxides to protect cells from oxidative damage.
Question 5: Which fat-soluble vitamin acts as an antioxidant by protecting polyunsaturated fatty acids in cell membranes from oxidation?
- Vitamin E (alpha-tocopherol) (Correct answer)
- Vitamin D
- Vitamin A
- Vitamin K
Correct answer: Vitamin E (alpha-tocopherol)
Alpha-tocopherol, the most biologically active form of vitamin E, donates a hydrogen atom to lipid peroxyl radicals, interrupting the chain reaction of lipid peroxidation.
Question 6: A clinical nutritionist sees a patient with glossitis, angular stomatitis, and a 'magenta tongue.' Which deficiency is suspected?
- Riboflavin (vitamin B2) (Correct answer)
- Niacin (vitamin B3)
- Thiamine (vitamin B1)
- Folate
Correct answer: Riboflavin (vitamin B2)
Riboflavin deficiency (ariboflavinosis) presents with oral-ocular-genital syndrome including angular stomatitis, cheilosis, glossitis, and corneal vascularization.
Clinical Nutritionist CCN Micronutrients and Deficiencies 2
Which B vitamin acts as a coenzyme in over 100 enzymatic reactions, particularly amino acid metabolism?