Clinical Nutritionist CCN Nutritional Biochemistry and Supplementation 1 — Questions and Answers
Question 1: Which omega-3 fatty acid is primarily responsible for anti-inflammatory effects through production of resolvins and protectins?
- EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) (Correct answer)
- ALA (alpha-linolenic acid)
- GLA (gamma-linolenic acid)
- CLA (conjugated linoleic acid)
Correct answer: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)
EPA and DHA are the long-chain omega-3s that directly produce anti-inflammatory eicosanoids, resolvins, and protectins; ALA must be converted to EPA/DHA with low efficiency.
Question 2: Coenzyme Q10 (ubiquinol/ubiquinone) plays what essential role in cellular metabolism?
- Electron carrier in the mitochondrial electron transport chain (ETC) (Correct answer)
- Cofactor for ATP synthesis in the cytoplasm
- Substrate for fatty acid beta-oxidation
- Precursor for steroid hormone synthesis
Correct answer: Electron carrier in the mitochondrial electron transport chain (ETC)
CoQ10 shuttles electrons between complexes I/II and complex III of the mitochondrial ETC, and its reduced form (ubiquinol) also acts as a lipid-soluble antioxidant.
Question 3: What is the function of the methionine cycle and why is it clinically important?
- It regenerates methionine from homocysteine, producing SAM for methylation reactions, and requires B12, folate, and B6 (Correct answer)
- It converts methionine to cysteine via the transsulfuration pathway exclusively
- It is responsible for producing creatine in the liver and kidneys
- It regulates branched-chain amino acid catabolism in skeletal muscle
Correct answer: It regenerates methionine from homocysteine, producing SAM for methylation reactions, and requires B12, folate, and B6
The methionine cycle produces S-adenosylmethionine (SAM), the universal methyl donor; impairment from B12/folate/B6 deficiency elevates homocysteine, a cardiovascular risk factor.
Question 4: Alpha-lipoic acid is considered a 'universal antioxidant' because:
- It is both water- and fat-soluble and can regenerate other antioxidants including vitamins C and E and glutathione (Correct answer)
- It contains all essential amino acids and micronutrients
- It acts exclusively in the mitochondria to neutralize reactive oxygen species
- It inhibits xanthine oxidase and reduces superoxide production
Correct answer: It is both water- and fat-soluble and can regenerate other antioxidants including vitamins C and E and glutathione
Unlike most antioxidants, alpha-lipoic acid functions in both aqueous and lipid environments and can recycle oxidized forms of vitamin C, vitamin E, and glutathione, amplifying overall antioxidant capacity.
Question 5: Which precursor is required for endogenous synthesis of carnitine, essential for mitochondrial fatty acid transport?
- Lysine and methionine, with cofactors vitamin C, B6, niacin, and iron (Correct answer)
- Tryptophan and threonine with pyridoxal phosphate
- Cysteine and glutamate with selenium
- Phenylalanine and arginine with zinc
Correct answer: Lysine and methionine, with cofactors vitamin C, B6, niacin, and iron
Carnitine is synthesized from lysine and methionine through a pathway requiring ascorbate, iron, pyridoxal phosphate, and niacin; deficiency impairs long-chain fatty acid entry into mitochondria.
Question 6: Phosphatidylcholine is a major membrane phospholipid that also serves as a precursor for which neurotransmitter?
- Acetylcholine (Correct answer)
- Serotonin
- Dopamine
- GABA
Correct answer: Acetylcholine
Choline from phosphatidylcholine is a direct precursor for acetylcholine synthesis in cholinergic neurons; adequate dietary choline is essential for cognitive function and neuromuscular transmission.
