CNS Dietary Supplements and Nutraceuticals 1 — Questions and Answers
Question 1: Which form of magnesium is most bioavailable and least likely to cause gastrointestinal side effects at therapeutic doses?
- Magnesium oxide
- Magnesium glycinate (Correct answer)
- Magnesium sulfate
- Magnesium carbonate
Correct answer: Magnesium glycinate
Magnesium glycinate is chelated to the amino acid glycine, which significantly enhances intestinal absorption and minimizes the laxative effect associated with poorly absorbed forms like magnesium oxide.
Question 2: A patient taking a statin medication asks about supplementing with CoQ10. Which statement best describes the rationale for CoQ10 supplementation in this context?
- Statins increase CoQ10 synthesis by upregulating the mevalonate pathway
- Statins inhibit the mevalonate pathway, reducing endogenous CoQ10 synthesis (Correct answer)
- CoQ10 supplementation prevents statin-induced hepatotoxicity
- CoQ10 directly lowers LDL cholesterol, enhancing statin efficacy
Correct answer: Statins inhibit the mevalonate pathway, reducing endogenous CoQ10 synthesis
Statins block HMG-CoA reductase in the mevalonate pathway, which is also required for CoQ10 (ubiquinone) synthesis, potentially contributing to statin-associated myopathy.
Question 3: Which of the following best describes the upper tolerable intake level (UL) concern with preformed vitamin A supplementation in pregnant women?
- Doses above 3,000 mcg RAE/day are associated with teratogenicity (Correct answer)
- Beta-carotene supplements carry the same teratogenic risk as retinol
- The UL for vitamin A does not apply during pregnancy
- Vitamin A toxicity only occurs with injectable forms
Correct answer: Doses above 3,000 mcg RAE/day are associated with teratogenicity
Preformed vitamin A (retinol) at doses exceeding 3,000 mcg RAE per day during pregnancy is associated with fetal birth defects; provitamin A carotenoids like beta-carotene do not carry this risk.
Question 4: A practitioner recommends a probiotic supplement containing Lactobacillus rhamnosus GG. This strain has the strongest evidence base for which clinical application?
- Reducing systolic blood pressure in hypertensive adults
- Reducing the duration of antibiotic-associated diarrhea (Correct answer)
- Improving insulin sensitivity in type 2 diabetes
- Lowering serum LDL cholesterol
Correct answer: Reducing the duration of antibiotic-associated diarrhea
Lactobacillus rhamnosus GG has the most robust evidence among probiotic strains for preventing and reducing the duration of antibiotic-associated diarrhea and certain infectious diarrheas.
Question 5: Which factor most significantly enhances the intestinal absorption of non-heme iron from a supplement?
- Consuming the supplement with a calcium-rich dairy product
- Taking the supplement concurrently with a proton pump inhibitor
- Co-ingesting the supplement with vitamin C (ascorbic acid) (Correct answer)
- Taking the supplement with a high-phytate grain product
Correct answer: Co-ingesting the supplement with vitamin C (ascorbic acid)
Vitamin C reduces ferric iron (Fe³⁺) to the more soluble ferrous form (Fe²⁺) and forms a soluble chelate, both of which substantially enhance non-heme iron absorption in the intestine.
Question 6: When counseling a patient about omega-3 fatty acid supplements for triglyceride reduction, which dose is generally supported by clinical evidence for a significant (>15%) triglyceride-lowering effect?
- 0.5–1 g EPA+DHA per day
- 1–2 g EPA+DHA per day
- 3–4 g EPA+DHA per day (Correct answer)
- 6–8 g EPA+DHA per day
Correct answer: 3–4 g EPA+DHA per day
Prescription-grade omega-3 formulations and meta-analyses consistently show that 3–4 g/day of EPA+DHA are required to achieve clinically meaningful reductions (typically 20–30%) in serum triglycerides.
Question 7: Which of the following best explains why methylfolate (5-MTHF) is often preferred over folic acid for individuals with MTHFR polymorphisms?
- Methylfolate bypasses the conversion step catalyzed by MTHFR, delivering the active form directly (Correct answer)
- Methylfolate has a longer half-life in serum than folic acid
- Folic acid competes with methylfolate at intestinal transport receptors in these individuals
- Methylfolate reduces homocysteine independently of the methionine cycle
Correct answer: Methylfolate bypasses the conversion step catalyzed by MTHFR, delivering the active form directly
The MTHFR enzyme converts 5,10-methyleneTHF to 5-MTHF; in individuals with reduced MTHFR activity, supplementing directly with 5-MTHF bypasses this impaired conversion step, ensuring adequate active folate is available.
CNS Dietary Supplements and Nutraceuticals 1
Which form of magnesium is most bioavailable and least likely to cause gastrointestinal side effects at therapeutic doses?