Q: Which equation best represents the regulation of blood calcium by vitamin D?

$$\text{Vitamin D} \xrightarrow{\text{liver, kidney}} \text{Calcitriol} \rightarrow \text{Increased intestinal Ca^{2+} absorption}$$

Question 1

Which of the following best explains why fat-soluble vitamins are more likely to cause toxicity than water-soluble vitamins?

Accepted Answer

Fat-soluble vitamins are stored in the liver and adipose tissue, while water-soluble vitamins are excreted in urine.

Question 2

A patient presents with night blindness and frequent infections. Which vitamin deficiency is most likely responsible, and what is a key food source to recommend?

Accepted Answer

Vitamin A; recommend liver and orange vegetables such as carrots.

Question 3

Which of the following statements about antioxidants is CORRECT?

Accepted Answer

Vitamin C and vitamin E both act as antioxidants by neutralizing free radicals.

Question 4

Which process is most likely to destroy riboflavin in foods?

Accepted Answer

Exposure to light

Question 5

A vegan patient is diagnosed with macrocytic anemia. Which nutrient deficiency is most likely, and what is a key factor in its absorption?

Accepted Answer

Vitamin B12; intrinsic factor is required for absorption.

Question 6

Which equation best represents the regulation of blood calcium by vitamin D?

Accepted Answer

$$	ext{Vitamin D} \xrightarrow{	ext{liver, kidney}} 	ext{Calcitriol} ightarrow 	ext{Increased intestinal Ca^{2+} absorption}$$

Question 7

Which of the following individuals is at greatest risk for developing a thiamin deficiency?

Accepted Answer

A chronic alcoholic due to impaired absorption and increased excretion.

Question 8

Which of the following best describes the difference between folate and folic acid?

Accepted Answer

Folate is the naturally occurring form in foods, while folic acid is the synthetic form found in supplements and fortified foods.

Question 9

A patient is prescribed high-dose niacin to lower cholesterol. Which side effect should they be most closely monitored for?

Accepted Answer

Flushing of the skin

Question 10

Which of the following minerals is emphasized in the DASH diet for blood pressure control?

Accepted Answer

Potassium, magnesium, and calcium

Question 11

Which of the following best explains why iron from animal sources is more bioavailable than iron from plant sources?

Accepted Answer

Heme iron from animal sources is absorbed more efficiently than nonheme iron from plants.

Question 12

Which of the following is a function of vitamin K?

Accepted Answer

Activation of proteins involved in blood clotting

Question 13

A patient with a genetic disorder affecting copper transport develops liver and neurological symptoms. Which disease is most likely?

Accepted Answer

Wilson's disease

Question 14

Which of the following best describes the role of hepcidin in iron metabolism?

Accepted Answer

Hepcidin decreases intestinal iron absorption by degrading ferroportin.

Question 15

Which of the following is a risk factor for osteoporosis?

Accepted Answer

Low calcium intake, advanced age, and physical inactivity

Question 16

Which of the following statements about dietary supplements is TRUE?

Accepted Answer

Supplements are regulated as foods, not drugs, in the United States.

Question 17

A patient presents with dermatitis, diarrhea, and dementia. Which vitamin deficiency is most likely?

Accepted Answer

Niacin (pellagra)

Question 18

Which of the following best describes the effect of avidin on biotin bioavailability?

Accepted Answer

Avidin binds biotin in raw egg whites, preventing its absorption.

Question 19

Which of the following is a key function of selenium in the body?

Accepted Answer

Acts as a cofactor for antioxidant enzymes such as glutathione peroxidase

Question 20

A patient with iron-deficiency anemia is advised to increase vitamin C intake. Why?

Accepted Answer

Vitamin C enhances nonheme iron absorption by reducing $$Fe^{3+} to$$ $$Fe^{2+}.$$

Micronutrients: Fat-Soluble Vitamins, Water-Soluble Vitamins, Major Minerals, and Trace Minerals

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