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Chapter 10 – The Water-Soluble Vitamins: B Vitamins and Vitamin C
Learning Objectives
After completing Chapter 10, the student will be able to:
10.2 Identify the main roles, deficiency symptoms, and food sources for each of the B vitamins.
a. List the B vitamins and identify the major functions of each vitamin in the body.
10.3 Identify the main roles, deficiency symptoms, and food sources for vitamin C.
a. List the major uses of vitamin C in the body.
10.4 Present arguments for and against the use of dietary supplements.
a. Explain the Dietary Supplement Health and Education Act of 1994 and how the consumer can use the
act in the selection of a nutrient supplement.
Assignments and Other Instructional Materials
The following ready-to-use assignments are available in this chapter of the instructor’s manual:
• Case Study: Fatigue with a Vitamin-Poor Diet
• New! Case Study: Folate and Vitamin C for Breakfast
Other instructional materials in this chapter of the instructor’s manual include:
• Answer key for How To (pp. 302, 306, 312) activities and study card questions
• Classroom activities, featuring New! meal comparison activity (10-7)
• Worksheet answer keys (as appropriate)
• Handout 10-1: RDA/AI and UL for Vitamins Compared
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Lecture Presentation Outline4
Key to instructor resource annotations (shown to the right of or below outline topics):
I. The Vitamins—An Overview – Explain and define the following:
Website HN 10-4, 10-5; IM WS 10-1, CA 10-1
A. Bioavailability IM WS 10-2
B. Precursors
C. Organic Nature – Discuss methods to prevent the loss of nutrients (Table 10-1) Website HN 10-2
D. Solubility
1. Water-soluble vitamins (B vitamins and vitamin C) are absorbed directly into the blood
2. Fat-soluble vitamins (vitamins A, D, K and E) are absorbed first into the lymph, then the blood
1. Water-soluble vitamins can reach toxic levels with supplement use
2. Fat-soluble vitamins are likely to reach toxic levels with supplement use
II. The B Vitamins 10e TRA 106
A. Part of coenzymes (Figure 10-2)
B. Thiamin (Vitamin B1) – Discuss the following:
1. Thiamin functions
2. Thiamin Recommendations
a. RDA for men: 1.2 mg/day
b. RDA for women: 1.1 mg/day
d. No reported toxicities
4. Thiamin Food Sources 10e TRA 107
a. Whole-grain, fortified, or enriched grain products (Figure 10-4)
b. Moderate amounts in all foods
c. Pork
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2. Riboflavin Recommendations
a. RDA for men: 1.3 mg/day
b. RDA for women: 1.1 mg/day
3. Riboflavin Deficiency and Toxicity
D. Niacin (Vitamin B3) – Discuss the following:
1. Niacin functions – Also called nicotinic acid, nicotinamide, and niacinamide
2. Niacin Recommendations
a. RDA for men: 16 NE/day
c. RDA for women: 14 NE/day
d. UL of 35 mg/day for adults
e. The amino acid tryptophan is the precursor
4. Rash when exposed to sunlight
4. Niacin Toxicity
a. Niacin flush
b. Toxicity symptoms
1. Painful flush, hives, and rash
2. Nausea and vomiting
3. Liver damage
4. Impaired glucose tolerance
5. Niacin Food Sources (Figure 10-8) 10e TRA 110
E. Biotin – Discuss the following:
1. Biotin functions
2. Biotin Recommendations – AI for adults: 30 g/day
3. Biotin Deficiency and Toxicity
a. Deficiencies are rare
b. Deficiency symptoms
1. Depression, lethargy, and hallucinations
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4. Biotin Food Sources
a. Widespread in foods
1. Pantothenic acid functions
2. Pantothenic Acid Recommendations – AI for adults: 5 mg/day
3. Pantothenic Acid Deficiency and Toxicity
a. Deficiency is rare
b. Deficiency symptoms
1. Vomiting, nausea, and stomach cramps
c. No reported toxicities
4. Pantothenic Acid Food Sources
e. Can be destroyed by freezing, canning, and refining
G. Vitamin B6 (pyridoxine, pyridoxal, or pyridoxamine)
1. Vitamin B6 functions
2. Vitamin B6 Recommendations – RDA for adults 19-50 years: 1.3 mg/day
3. Vitamin B6 Deficiency
a. Deficiency symptoms
1. Scaly dermatitis
4. Vitamin B6 Toxicity
a Toxicity symptoms
1. Depression, fatigue, irritability, and headaches
b. UL for adults: 100 mg/day
5. Vitamin B6 Food Sources (Figure 10-9) 10e TRA 111
a. Meats, fish, poultry, and liver
b. Legumes and soy products
H. Folate (folic acid, folacin, pteroylglutamic acid or PGA) – Discuss the following: 10e TRA 112
1. Introduction
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c. There are higher recommendations for pregnant women
3. Folate and Neural Tube Defects 13e TRA 16
a. Spina bifida and anencephaly
c. Pregnant women should take folate supplements
4. Folate and Heart Disease
5. Folate and Cancer – Folate may help to prevent cancer, but may also promote cancer growth once
cancer has developed
1. Macrocytic anemia, also called megaloblastic anemia
2. Smooth, red tongue
3. Mental confusion, weakness, fatigue, irritability, and headaches
3. Oral contraceptives
7. Folate Toxicity
a. Masks vitamin B12 deficiency symptoms
b. UL for adults: 1000 g/day
8. Folate Food Sources (Figure 10-13) 10e TRA 113
a. Fortified grains
I. Vitamin B12 (cobalamin) – Discuss the following:
1. Introduction
2. Vitamin B12 Recommendations – RDA for adults: 2.4 g/day
3. Vitamin B12 Deficiency and Toxicity
a. Deficiency symptoms 13e TRA 13; 10e TRA 114
1. Anemia – large cell type (Figure 10-12)
2. Fatigue and degeneration of peripheral nerves progressing to paralysis
4. Vitamin B12 Food Sources
a. Meat, fish, poultry, and shellfish
d. Easily destroyed by microwave cooking
J. Choline
1. Choline functions
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2. Choline Recommendations
a. AI for men: 550 mg/day
b. AI for women: 425 mg/day
4. Choline Food Sources – Milk, liver, eggs, and peanuts
K. Nonvitamins
1. Inositol
2. Carnitine
3. Other nonvitamins
L. Interactions among the B Vitamins
1. B Vitamin Roles 10e TRA 115
2. B Vitamin Deficiencies
a. Deficiencies rarely occur singly except for beriberi and pellagra
b. Can be primary or secondary causes
c. Glossitis and cheilosis are two symptoms common to B vitamin deficiencies (Figure 10-15)
d. Symptoms that individuals experience are not necessarily related to a vitamin deficiency
3. B Vitamin Toxicities – Can occur with supplements
III. Vitamin C (also called ascorbic acid; antiscorbutic factor is the original name for vitamin C)
A. Vitamin C Roles
1. As an Antioxidant (Figure 10-16)
a. Defends against free radicals
b. Protects tissues from oxidative stress
2. As a Cofactor in Collagen Formation Website HN 10-3
a. Collagen is used for bones and teeth, scar tissue, and artery walls
b. Works with iron to form hydroxiproline, which is needed in collagen formation
B. Vitamin C Recommendations (Figure 10-17) 10e TRA 116
1. RDA for men: 90 mg/day
2. RDA for women: 75 mg/day
D. Vitamin C Toxicity
1. Toxicity symptoms
a. Nausea, abdominal cramps, diarrhea, headache, fatigue, and insomnia
b. Hot flashes and rashes
c. Interference with medical tests, creating a false positive or a false negative
d. Aggravation of gout symptoms, urinary tract infections, and kidney stones
2. UL for adults: 2000 mg/day
E. Vitamin C Food Sources (Figure 10-19) 10e TRA 117
1. Citrus fruits, cantaloupe, strawberries, papayas, and mangoes
IV. Highlight: Vitamin and Mineral Supplements
A. Arguments for Supplements
1. Correct Overt Deficiencies
2. Support Increased Nutrient Needs
a. People with nutritional deficiencies
b. People with low energy intake – less than 1600 kcalories per day
c. Vegetarians and those with atrophic gastritis need vitamin B12
d. People with lactose intolerance, milk allergies, or inadequate intake of dairy foods need calcium
e. People in certain stages of the life cycle
B. Arguments against Supplements
1. Who Should Not Take Supplements?
a. Iron – men and postmenopausal women
b. Beta-carotene – smokers
2. Toxicity
3. Life-Threatening Misinformation
4. Unknown Needs
5. False Sense of Security
6. Other Invalid Reasons:
a. Belief that food supply and soil contain inadequate nutrients
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7. Bioavailability and Antagonistic Actions
C. Selection of Supplements – Need to consider: IM WS 10-3, CA 10-8, 10-9
1. Form
2. Contents
D. Regulation of Supplements
1. Nutritional labeling for supplements is required (Figure H10-1)
2. Labels may make nutrient claims according to specified criteria
3. Labels may claim that lack of a nutrient can cause a deficiency disease and include the prevalence of
that disease
Case Studies5
Case Study 10-1: Fatigue with a Vitamin-Poor Diet
Samuel is a 63-year-old single man who works full time in a food processing plant. He has a history of esophageal
cancer which was treated successfully with anti-cancer drugs and surgery four years ago. His weight had been stable
at 135 pounds until the past 6 months, in which he has experienced an involuntary weight loss of 10 pounds. He is
67 inches tall and his current BMI is 19.5. He complains of a poor appetite and being overly weak and tired. His
usual diet is fairly consistent. He states he rarely eats breakfast because he starts work at 6 a.m. He eats two deli
meat sandwiches, “usually pastrami or salami,” and a soda at 10 a.m. and may eat a candy bar in the afternoon when
he gets off work. He often prepares frozen dinners or pizza at home in the evening and routinely drinks “about 2 or 3
beers” before going to bed. Occasionally he will cook a roast and mashed potatoes. He occasionally will have milk
with cereal but rarely eats vegetables or fruit. He would like to know which vitamin supplement will give him
energy.
1. From what you have learned about the functions of vitamins, how would you answer Samuel’s question?
2. What are some indications that Samuel’s diet could be low in thiamin?
3. Using information from Figure 10-4, what are one or two good sources of thiamin from each food group that
would be fairly easy for Samuel to add to his diet?
4. What other vitamins would you suspect might be deficient in Samuel’s diet? Why?
5. Besides his diet, how might Samuel’s medical history have increased his risk for folate deficiency?
6. Based on his medical history and information in this chapter, how would you advise Samuel regarding his
complaints of fatigue and weight loss?
7. Would you recommend a daily multivitamin supplement for Samuel based on the history he has provided? Why
or why not?
Answer Key
1. Vitamin supplements do not provide as many benefits as vitamin-rich foods. Vitamins do not provide energy
but assist the enzymes that release energy from carbohydrates, fats, and proteins in foods.
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Case Study 10-2: Folate and Vitamin C for Breakfast
Lydia S. is a 42-year-old British woman who recently moved to the United States. She smokes a half pack of
cigarettes a day. She is 64 inches tall, weighs 185 pounds, and has a family history of heart disease. Her diet is high
in protein, mostly from beef and chicken. She dislikes most vegetables except corn and potatoes. She eats fruit only
occasionally and often skips breakfast. After taking a nutrition class at a local community college, Lydia is
concerned that her diet may be deficient in folate and vitamin C. When she looks at the Nutrition Facts for some
foods in her pantry, this is what she finds:
Instant Breakfast Essentials powder, 1 packet: 50% vitamin C, 25% folate
Ovaltine drink mix, 2 T: 10% vitamin C, 0% folate
Raisin Bran cereal, 1 cup: 0% vitamin C, 25% folate
Toasted oats cereal, 1 cup: 10% vitamin C, 50% folate
1. Lydia learned in class that 400 micrograms provides 100% of the Daily Value for folate. Show how she can
calculate the amount of folate in each of these foods. Then, show how Lydia can use the “How To” feature on
page 312 to calculate the dietary folate equivalents (DFE) for each of these fortified foods.
2. Lydia also learned that 60 milligrams provides 100% of the Daily Value for vitamin C. Show how she can
calculate the amount of vitamin C in each of these foods.
3. Based on her current diet, which food group is most likely the primary source of folate in Lydia’s diet? What
explains the high amount of folate in these foods?
4. Considering her current diet and lifestyle habits, why might Lydia need extra vitamin C in her diet?
5. Even if she were to achieve 100% of the Daily Value for vitamin C from the fortified foods in her pantry, what
are some reasons that Lydia should still consider increasing her intake of fresh fruits and vegetables?
6. Based on her family history, why is it important for Lydia to get an adequate amount of folate in her daily diet?
7. Show how Lydia might combine the foods in her pantry with some of the foods listed in Figure 10-12 and
Figure 10-19 to plan one day of meals that meet her requirements for dietary folate equivalents (DFE) and
vitamin C.
Answer Key
1. Instant Breakfast: 400 micrograms × 0.25 = 100 micrograms folate x 1.7 = 170 micrograms DFE; Ovaltine: 0
micrograms folate; Raisin Bran: 400 micrograms × 0.25 = 100 micrograms folate × 1.7 = 170 micrograms DFE;
toasted oats cereal: 400 micrograms x 0.5 = 200 micrograms folate × 1.7 = 340 micrograms DFE.
Suggested Classroom Activities
The B vitamins’ involvement in metabolism offers an opportunity to review that subject. If you want to incorporate
information on alcohol and nutrition not previously covered, understanding of the B vitamins’ roles in metabolism
of the energy-yielding nutrients makes it possible to appreciate, more deeply than before, the nutritional impact that
alcohol has on the body (see Highlight 7). The information on vitamin C can be used as an opportunity to teach
students about experimental design (introduced in Chapter 1).
Classroom Activity 10-1: Vitamin Discovery Timelines
Key concept: Historical progress of nutrition science Class size: Any
Instructions: Set the stage for the importance of the vitamins by taking the students back historically to the time
before vitamins were discovered. Discuss the events leading up to the discovery of vitamins, including the life-
saving outcomes. (You may wish to present information in Handouts 10-3 and 10-4, available from the website.)
This approach may enhance students’ appreciation for the miraculous functions of these nutrients.
Classroom Activity 10-4: A Vitamin Interview6
Key concept: Characteristics of vitamins Class size: Any
Instructions: To help students learn all the vitamins, set up “The Body Company.” Have each student “apply” for a
job as a vitamin by describing (in an interview) what that vitamin can do for “The Body Company” and which other
nutrients it works best with.
Classroom Activity 10-5: Vitamin Vocabulary Worksheets7
Key concept: Characteristics of vitamins Class size: Any
Instructions: Ask students to write an original sentence using an assigned vitamin term. Then combine all of the
students’ sentences into a worksheet, removing the term used in the sentence, and replacing it with a blank line. At
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the end of the worksheet list all of the terms used alphabetically. The students have the fun of seeing their writing in
print and are much more likely to enjoy the process than they would filling in the blanks of a “canned” worksheet.
Example (answer is “niacin”):
Classroom Activity 10-6: Vitamin Review
Objective: Review Class size: Any
Instructions: Have students keep their books and notes open. Start by asking a student to name one vitamin. Then
tell the next student to add some bit of information about that vitamin, and so on, until you get four items of
information about that vitamin. The next student names another vitamin. Repeat until all of the nutrients covered in
this section have been reviewed.
Classroom Activity 10-7: Putting Nutrient Density into Practice (Meal Comparison)8
Key concept: Identifying food sources of water-soluble vitamins Class size: Any
Instructions: Present the three lunch meal plans below to students and use the discussion questions to prompt them
to evaluate the plans.
Lunch #1
Beef and bean burrito, 1 item
Mexican rice, white, 1 cup
Bottled water
Lunch #2
Hamburger, plain, 1 small
French fries, 1 medium
Diet cola
Lunch #3
Bread, whole-wheat, 2 slices
Peanut butter, chunky, 2 Tbsp
Jam, 1 Tbsp
Yogurt, low-fat, 1 cup
Grapes, 1 cup
Broccoli, raw, 1 cup
Discussion questions:
1. What are the DRIs for a non-pregnant adult female for riboflavin, folate, vitamin B12, and vitamin C? (Hint: Use
the chart inside the front cover of your textbook.)
2. Which meal would be most helpful in meeting the DRIs for riboflavin, folate, vitamin B12, and vitamin C?
3. Which foods are highest in these nutrients?
4. What changes could be made to the meal plans to improve their nutrient density?
Answer key:
1. Riboflavin: 0.9 milligrams; folate: 320 micrograms; vitamin B12: 2.0 micrograms; vitamin C: 60 milligrams
Nutrient composition of meals for instructor reference:
Lunch #1 Menu Item
Cal
Rb
Fo
B12
Vit C
Beef and bean burrito, 1 item
332
0.24
123
0.7
1
Mexican rice, white, 1 cup
166
0.14
43
0
0
Bottled water
0
0
0
0
0
Totals
498
0.38
166
0.7
1
183
Lunch #2 Menu Item
Cal
Rb
Fo
B12
Vit C
Hamburger, plain, 1 small
254
0.24
72
0.86
0
French fries, 1 medium
421
0.09
40
0
4
Diet cola
0
0
0
0
0
Totals
675
0.33
112
0.86
4
Classroom Activity 10-8: Demonstration—Vitamin Supplement Dissolvability
Key concept: Choosing a dietary supplement, dissolvability Class size: Any
Materials needed: Plastic cups and coffee stirrers for each student, large bottle of vinegar
Instructions: Instruct students to bring nutrient supplements to the next class. Bring vinegar and clear plastic cups.
The purpose of this activity is to demonstrate disintegration characteristics of vitamin/mineral supplements.
Supplements that do not disintegrate have little chance of entering the bloodstream. To demonstrate how well or
how poorly different vitamin/mineral supplements dissolve in the stomach, conduct an experiment by filling several
clear plastic cups with vinegar (to mimic the pH of the stomach). Place one supplement in each cup and every 5
minutes stir or swirl the contents. Leave supplements in the cups for approximately 15-30 minutes. Observe what
happens. See if there are differences between time-released supplements and others. Discuss the many implications.
This activity can be used as a vehicle for discussing many issues related to supplementation, including appropriate
and inappropriate reasons for taking supplements and guidelines for supplement selection. Worksheet 10-3 can be
used in conjunction with this activity to provide an avenue for evaluating supplements.
How To “Try It” Activities Answer Key
How to Evaluate Foods for Their Nutrient Contributions
The pork chop provides more riboflavin per 1-ounce serving (0.083 mg/oz. for the pork chop vs. 0.073 mg/oz. for
the cheese) and is also more nutrient dense with respect to riboflavin (0.000859 mg/kcal for the pork chop vs.
0.000667 mg/kcal for the cheese).
How to Estimate Niacin Equivalents
16 mg NE
How to Estimate Dietary Folate Equivalents
587.5 µg DFE
