Question 1

Which of the following statements best explains why water-soluble vitamins seldom reach toxic levels in the body?

Accepted Answer

They are easily absorbed and excreted, and not stored extensively in tissues.

Question 2

A patient presents with fatigue, dermatitis, diarrhea, and dementia. Which vitamin deficiency is most likely responsible for these symptoms?

Accepted Answer

Vitamin B\_3 (niacin)

Question 3

Which process is described as adding nutrients back to foods that have lost nutrients during processing, such as adding B vitamins to white rice?

Accepted Answer

Enrichment

Question 4

A vegan is at increased risk for which vitamin deficiency, and what is the best dietary strategy to prevent it?

Accepted Answer

Vitamin B\_{12}; consume fortified foods or supplements

Question 5

Which vitamin acts as a coenzyme in the breakdown of glucose for energy and is especially important for nerve function?

Accepted Answer

Vitamin B\_1 (thiamin)

Question 6

A patient who consumes large amounts of raw egg whites daily develops symptoms of biotin deficiency. What is the most likely explanation?

Accepted Answer

Egg whites contain avidin, which binds biotin and prevents its absorption.

Question 7

Which of the following is a function of vitamin C (ascorbic acid) in the body?

Accepted Answer

Enhances iron absorption and acts as an antioxidant

Question 8

A woman in early pregnancy is advised to increase her intake of which vitamin to prevent neural tube defects in her baby?

Accepted Answer

Vitamin B\_9 (folate)

Question 9

Which of the following factors does NOT decrease the bioavailability of vitamins?

Accepted Answer

Consuming fat-soluble vitamins with dietary fat

Question 10

A patient with atrophic gastritis is most at risk for which deficiency, and why?

Accepted Answer

Vitamin B\_{12} deficiency, due to impaired absorption in the GI tract

Question 11

Which vitamin is involved in the conversion of homocysteine to methionine and is necessary for the maintenance of myelin on nerves?

Accepted Answer

Vitamin B\_{12} (cobalamin)

Question 12

Which of the following is a potential negative outcome of excessive folic acid fortification in the population?

Accepted Answer

Masking of vitamin B\_{12} deficiency symptoms

Question 13

A patient presents with poor wound healing, bleeding gums, and fatigue. Which vitamin deficiency is most likely?

Accepted Answer

Vitamin C (ascorbic acid)

Question 14

Which of the following best describes the role of antioxidants in the body?

Accepted Answer

They donate electrons to free radicals, stabilizing them and preventing cellular damage.

Question 15

Which vitamin is required for the conversion of tryptophan to niacin and is also involved in amino acid metabolism?

Accepted Answer

Vitamin B\_6 (pyridoxine)

Question 16

A patient taking high-dose niacin supplements for cholesterol management develops flushing, tingling in the hands and feet, and blurred vision. What is the most likely cause?

Accepted Answer

Niacin toxicity from supplements

Question 17

Which of the following is a unique property of riboflavin (vitamin B\_2) compared to other B vitamins?

Accepted Answer

It is easily destroyed by heat and exposure to light.

Question 18

Which vitamin is necessary for the synthesis and maintenance of collagen, and what is a classic deficiency disease associated with it?

Accepted Answer

Vitamin C; scurvy

Question 19

A patient with a history of alcoholism presents with confusion, memory disturbances, and psychosis. Which vitamin deficiency is most likely, and what is the syndrome called?

Accepted Answer

Thiamin (B\_1) deficiency; Wernicke-Korsakoff syndrome

Question 20

Which of the following best describes the difference between fortification and enrichment of foods?

Accepted Answer

Fortification adds nutrients not originally present; enrichment replaces nutrients lost during processing.

Water-Soluble Vitamins: Structure, Function, and Importance in Human Nutrition

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