CNS Dietary Supplements and Nutraceuticals 3

Question 1

Which selenium species has the highest bioavailability and is the preferred form for supplementation aimed at increasing glutathione peroxidase activity?

Accepted Answer

Selenomethionine

Answer

Selenomethionine is the organic form found in plant-based foods and has approximately 90% bioavailability compared to ~50% for inorganic selenite, making it the preferred supplemental form for raising selenium status.

Question 2

Which of the following best describes the Tolerable Upper Intake Level (UL) for selenium in adults and the primary toxicity concern at doses above the UL?

Accepted Answer

UL = 400 mcg/day; primary concern is selenosis (hair loss, nail brittleness, neurological effects)

Answer

The UL for selenium is 400 mcg/day for adults; chronic intake above this threshold causes selenosis, characterized by garlic breath, alopecia, nail changes, and in severe cases peripheral neuropathy.

Question 3

A patient with Hashimoto's thyroiditis asks about iodine supplementation. Which recommendation is most clinically appropriate?

Accepted Answer

Iodine supplementation above the RDA should be approached cautiously as excess iodine can trigger autoimmune thyroid flares

Answer

Excess iodine can increase thyroid peroxidase antibody titers and trigger flares in Hashimoto's thyroiditis; supplementation above the RDA (150 mcg/day) should be individualized and closely monitored.

Question 4

Alpha-lipoic acid (ALA) is classified as both a water-soluble and fat-soluble antioxidant. Which clinical application has the strongest evidence base for ALA supplementation?

Accepted Answer

Improving symptoms of diabetic peripheral neuropathy

Answer

Multiple RCTs and systematic reviews support ALA supplementation (600–1,800 mg/day) for reducing pain, burning, and paresthesia in diabetic peripheral neuropathy, where it is approved as a pharmaceutical in some European countries.

Question 5

Which statement most accurately describes the regulatory classification of dietary supplements under the Dietary Supplement Health and Education Act (DSHEA) of 1994?

Accepted Answer

Supplements are regulated as food, placing the burden of proving unsafe products on the FDA after they are marketed

Answer

DSHEA classifies supplements as a subset of food, meaning manufacturers are responsible for safety but do not require pre-market FDA approval; the FDA must demonstrate that a product is unsafe to remove it from the market.

CNS - Certified Nutrition Specialist Exam Practice Test

CNS - Certified Nutrition Specialist Exam Practice Test

CNS Dietary Supplements and Nutraceuticals 3