Pennsylvania State University - NUTR 251

Water-soluble Vitamins (Chapter 10)

General Questions

1)Define a coenzyme. Name the water-soluble vitamins which are coenzymes and list their coenzyme names.

2. Describe the common characteristics of all vitamins. Then describe similarities and differences between fat- soluble and water-soluble vitamins.

Niacin, Thiamin, Riboflavin, Pantothenic Acid, and Vitamin B₆

1. Why is beriberi a potential problem in populations which consume most of their kcals from “polished” rice? Americans eat lots of polished rice, yet do not get beriberi, why?
2. Pellagra was in epidemic proportions in this country around 1910-1930.

What are the symptoms of this disease? What were the dietary conditions which precipitated this disease? What was the significance of a low protein diet? How did our public health officials resolve the situation so that pellagra is now eradicated in this country?

3. What is the significance of tryptophan in the diet in terms of niacin

nutrition?

4. Describe in a brief sentence the roles of niacin (NADH) and riboflavin

(FADH2) coenzymes in ATP production.

5. Why is there a UL for niacin? Note that the UL reflects quantity in a supplement rather than niacin in food.

6. Why is there no pantothenic acid deficiency in the US? What is the role of pantothenic acids; specifically what enzyme do you know to which it is a coenzyme?
7. Biotin is needed to keep the TCA cycle going by making oxaloacetate

from pyruvate as well as for other metabolic needs such as fatty acid metabolism. We get biotin from two sources; explain.

8. Vitamin B₆ facilitates the release of energy like other B vitamins, but

from protein rather than carbohydrates and fats. Explain.

1. • Folic Acid and Vitamin B₁₂
1. Explain the statement: Vitamin B₁₂ deficiency causes a folate deficiency. What distinguishes pernicious anemia from megaloblastic anemia (i.e. folate deficiency)?

2. Explain the roles of folate and B₁₂ in blood health.
3. Describe vitamin B₁₂’s second role in the body.
4. Explain the issue which prompted the Food and Drug Administration

(FDA) to approve the enrichment of flour (and other cereal products) with folate? What is neural tube defect? Why must women during their childbearing years (even before they are pregnant) be aware of their folate intake?

5. List foods rich in folate.
6. Why are vegans at risk for low B₁₂ nutritional status?
7. Why does it take years to develop B₁₂ deficiency and only weeks or months to produce folate deficiency?
8. What are the roles of gastric acid (HCl) and Intrinsic Factor (IF) in B₁₂

absorption? Why are elderly at risk for B₁₂ deficiency (pernicious anemia)? What is atrophic gastritis?

Vitamin C

1. A person suffering from scurvy has pinpoint hemorrhaging in the skin and at points of the body where there is mechanical stress, like on the gums and joints. Why?
2. List rich food sources of vitamin C.

Fat-Soluble Vitamins (Chapter 11)

Vitamin A

1. How are fat-soluble vitamins absorbed into the body? Contrast this to water-soluble vitamins.
2. To meet one’s need for vitamin A, rich sources of carotenoid-containing vegetables only need to be consumed a few times each month. Why?

Compare plant and animal sources of vitamin A. Is milk a good source of vitamin A?

1. The first symptom of vitamin A deficiency is night blindness. What is night blindness and why does low vitamin A status cause it?
2. With severe vitamin A deficiency Xerophthalmia may result. What is

Xerophthalmia?

3. Explain the risk associated with hypervitaminosis A or vitamin A toxicity from retinoids.

Vitamin D

1. Vitamin D has been described as both a vitamin and a hormone. Explain your answer.
2. We can synthesize vitamin D in our liver from cholesterol. List the steps

involved in this conversion.

3. Vitamin D as 1,25 dihydroxy vitamin D has 3 target tissues. Name

those tissues (i.e. organs). Now describe what the physiological response is when calcium is low in the blood and vitamin D is activated.

4. How much sunshine weekly and to how much skin surface would you

recommend to people who consume little or no dairy products? How does this recommendation change with individuals with darker skin color? How does living north of 40° latitude (including central Pennsylvania) impact vitamin D needs throughout the year?

5. Describe rickets versus osteomalacia.

Vitamin E (and other Antioxidants)

1. What is a free radical? Are they normally produced in the body? Why must the body have controls over free radical production? What types

of molecules are being protected and why? What is one positive role of free radicals in the body?

2. In your own words, describe the role of vitamin E as an antioxidant. Do

carotenoids function as antioxidants? Does vitamin A?

3. What are major food sources of vitamin E?

Vitamin K

1. Is vitamin K’s role in the body as a coenzyme? What is vitamin K’s role in the clotting process?
2. Is there risk of low vitamin K status in any human populations in the

U.S.? Explain. What has been done in the U.S. to alleviate this problem?

3. Some vitamin K is from a non-dietary source. Explain. What foods are

rich in vitamin K?