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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:
1. Define a vitamin and classify vitamins as water soluble or fat soluble.
2. List the B vitamins and identify the major functions of each vitamin in the body.
3. Identify the non-B vitamins.
4. Describe the role of B vitamins in metabolism.
Assignments and Other Instructional Materials
The following ready-to–use assignments are available in this chapter of the instructor’s manual:
• New! Case study
• Worksheet 10-1: Vitamin History in Clinical Research1
Other instructional materials in this chapter of the instructor’s manual include:
• Answer key for How To (pp. 316, 320, 327) activities
• Classroom activities
• Worksheet answer keys (as appropriate)
• New! Handout 10-1: RDA/AI and UL for Vitamins Compared
• Handout 10-5: Timeline of Vitamin Discoveries by Vitamin
Lecture Presentation Outline4
“Of special interest to…” symbol key: = Hot Topic = Personal Health
= Health Care Professionals = Science Majors
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Key to instructor resource annotations (shown to the right of or below outline topics):
PL = Available on Power Lecture DVD-ROM (ISBN 0538797592): V = video
TRA = Transparency acetates: 12e TRA = 12th edition, 11e TRA = 11th edition, 10e TRA = 10th edition
Introductory/whole chapter resources: PL figure JPEGs; Test Bank; IM WS 10-4, 10-5, CA 10-1, 10-3, 10-4, 10-5,
10-6, 10-7, CI 10.1
I. The Vitamins—An Overview Website HN 10–4, 10–5; IM WS 10–1, CA 10-2
Vitamins differ from carbohydrate, fat, and protein in structure, function, and food contents. Vitamins are
A. Bioavailability is the rate and extent that a nutrient is absorbed and used. IM WS 10-2
B. Precursors, also known as provitamins, are consumed in an inactive form and become active vitamins in
the body.
C. The organic nature of vitamins means they can be destroyed by exposure to light, oxidation, cooking, and
storage. There are methods used to minimize nutrient losses. Website HN 10-2
1. Refrigerate fruits and vegetables.
D. Solubility
1. Water-soluble vitamins (B vitamins and vitamin C) are absorbed directly into the blood and travel
freely.
a. Circulate freely.
E. Toxicity 10e TRA 105; IM HN 10-1
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—As Individuals 10e TRA 106; IM CI 10.2, 10.3
The B vitamins are very active in the body. Several of the B vitamins form part of the coenzymes that assist
A. Thiamin (Vitamin B1) – Thiamin is involved in energy metabolism as part of the coenzyme thiamin
pyrophosphate (TPP).
1. Thiamin Recommendations
2. Thiamin Deficiency and Toxicity
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1. Enlarged heart and possible cardiac failure.
2. Muscular weakness.
d. No reported toxicities.
3. Thiamin Food Sources 10e TRA 107
4. Other Information
a. Steaming and microwaving are cooking methods that conserve thiamin.
b. Thiamin leaches into water with boiling or blanching.
c. The vitamin is easily destroyed by heat.
B. Riboflavin (Vitamin B2) –Riboflavin is involved in energy metabolism. Flavin mononucleotide (FMN) and
flavin adenine dinucleotide (FAD) are the coenzyme forms. 10e TRA 108
1. Riboflavin Recommendations
2. Riboflavin Deficiency and Toxicity
a. Deficiency symptoms
1. Sore throat and cracks and redness at the corners of the mouth.
3. Painful, smooth, and purplish red tongue.
4. Skin lesions covered with greasy scales.
3. Riboflavin Food Sources 10e TRA 109
4. Other information
a. Easily destroyed by ultraviolet light and irradiation.
b. Not destroyed by cooking.
C. Niacin (Vitamin B3) – Niacin is involved in the metabolism of glucose, fat, and alcohol. Nicotinamide
adenine dinucleotide (NAD), and NADP, the phosphate form of NAD, are the coenzyme forms.
1. Niacin Recommendations
a. The body can obtain niacin from dietary niacin and dietary tryptophan (60 mg of dietary
2. Niacin Deficiency
a. A deficiency of niacin results in the disease pellagra.
b. Deficiency symptoms
1. Diarrhea, abdominal pain, and vomiting.
2. Inflamed, swollen, smooth, and bright red tongue.
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5. Impaired glucose tolerance.
4. Niacin Food Sources 10e TRA 110
5. Other Information
a. Also called nicotinic acid, nicotinamide, and niacinamide.
b. The amino acid tryptophan is the precursor.
c. The vitamin can be lost from foods when it leaches into water.
d. Resistant to heat.
D. Biotin – As part of a coenzyme used in energy metabolism, biotin assists in glycogen synthesis, fat
synthesis, and amino acid metabolism.
1. Biotin Recommendations – AI Adults: 30 g/day.
2. Biotin Deficiency and Toxicity
a. Deficiencies are rare.
b. Deficiency symptoms
3. Biotin Food Sources
a. Widespread in foods.
4. Biotin can also be synthesized by intestinal bacteria.
E. Pantothenic Acid – Pantothenic acid is involved in energy metabolism as a part of coenzyme A.
1. Pantothenic Acid Recommendations – AI Adults: 5 mg/day.
2. Pantothenic Acid Deficiency and Toxicity
a. Deficiency is rare.
b. Deficiency symptoms
1. Vomiting, nausea, and stomach cramps.
5. Numbness, muscle cramps, and inability to walk.
c. No reported toxicities.
3. Pantothenic Acid Food Sources
a. Widespread in foods.
b. Chicken, beef, liver, and egg yolks.
F. Vitamin B6 (pyridoxine, pyridoxal, or pyridoxamine) – The coenzyme forms of vitamin B6 (pyridoxal
phosphate [PLP] and pyridoxamine phosphate [PMP]) are involved in amino and fatty acid metabolism,
the conversion of tryptophan to niacin or serotonin, and the production of red blood cells.
1. Vitamin B6 Recommendations – RDA Adults 19-50 years: 1.3 mg/day.
2. Vitamin B6 Deficiency
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3. Vitamin B6 Toxicity
a Toxicity symptoms
1. Depression, fatigue, irritability, and headaches.
2. Nerve damage causing numbness and muscle weakness leading to inability to walk.
b. Upper level for adults: 100 mg/day.
4. Vitamin B6 Food Sources 10e TRA 111
a. Meats, fish, poultry, and liver.
5. Other Information
a. Easily destroyed by heat.
b. Vitamin B6 appears to be ineffective in curing carpal tunnel syndrome.
G. Folate (folic acid, folacin, pteroylglutamic acid-PGA) – Folate is involved in the synthesis of DNA and the
formation of new cells. The coenzymes THF (tetrahydrofolate) and DHF (dihydrofolate) require vitamin
B12 to function correctly. 10e TRA 112
1. Folate Recommendations
a. RDA Adults: 400 g/day.
2. Folate and Neural Tube Defects
a. Neural tube defects include spina bifida and anencephaly.
3. Folate and Heart Disease
4. Folate may help to prevent cancer, but may also promote cancer growth once cancer has developed.
5. Folate Deficiency
a. Deficiency symptoms
1. Macrocytic anemia, also called megaloblastic anemia – large cell type.
2. Smooth, red tongue.
5. Elevated homocysteine levels.
b. Most vulnerable of all the vitamins to interactions with medications.
1. Anticancer drugs.
2. Antacids and aspirin.
3. Oral contraceptives.
6. Folate Toxicity
7. Folate Food Sources 10e TRA 113
a. Fortified grains.
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8. Other Information
a. Easily destroyed by heat and oxygen.
H. Vitamin B12 (Cobalamin) – Vitamin B12 is involved in the synthesis of new cells, maintains nerve cells,
reforms folate coenzymes, and helps break down some fatty acids and amino acids. Methylcobalamine
and deoxyadenosylcobalamin are the coenzyme forms.
1. Vitamin B12 Recommendations
a. RDA Adults: 2.4 g/day.
b. Atrophic gastritis in older adults destroys stomach cells, which diminishes intrinsic factor and
hydrochloric acid production.
c. Deficiency disease is called pernicious anemia.
d. No known toxicities
3. Vitamin B12 Food Sources.
a. Meat, fish, poultry, and shellfish.
4. Other Information
I. Vitamin-Like Compounds
1. Choline – Choline is involved in the synthesis of acetylcholine and lecithin.
a. Choline recommendations
1. AI Men: 550 mg/day.
2. AI Women: 425 mg/day.
b. Choline deficiency and toxicity
1. Deficiencies are rare.
2. Deficiency symptom is liver damage.
3. Toxicity symptoms
a. Body odor and sweating.
2. Inositol and Carnitine
a. Inositol is made from glucose and is part of the cell membrane structure.
b. Carnitine is made from lysine and transports long-chain fatty acids to be oxidized.
III. The B Vitamins—In Concert 10e TRA 115
The B Vitamins are interdependent. The presence of one may affect the absorption, metabolism, and excretion
of another. A deficiency of one may affect the functioning or deficiency of another. A variety of foods from
each food group will provide an adequate supply of all the B vitamins.
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3. Build new cells to deliver oxygen and nutrients for energy reactions.
B. B Vitamin Deficiencies
1. Deficiencies rarely occur singly except for beriberi and pellagra.
C. B vitamin toxicities can occur with supplements.
D. B Vitamin Food Sources
1. Grains group provides thiamin, riboflavin, niacin and folate.
IV. Vitamin C (antiscorbutic factor is the original name for vitamin C)
Vitamin C serves as a cofactor to facilitate the action of an enzyme and also serves as an antioxidant.
A. Vitamin C Roles
1. As an Antioxidant
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 10e TRA 116; CI 10.3
2. RDA Women: 75 mg/day.
3. Smokers: +35 mg/day.
C. Vitamin C Deficiency
1. Deficiency disease is called scurvy.
2. Deficiency symptoms
a. Anemia – small cell type.
b. Atherosclerotic plaques and pinpoint hemorrhages.
D. Vitamin C Toxicity
1. Toxicity symptoms
a. Nausea, abdominal cramps, diarrhea, headache, fatigue, and insomnia.
2. Upper level for adults: 2000 mg/day.
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E. Vitamin C Food Sources 10e TRA 117; IM CI 10.2
1. Citrus fruits, cantaloupe, strawberries, papayas, and mangoes.
V. Highlight: Vitamin and Mineral Supplements PL V “Vitamin/Mineral Supplements”; IM CI Highlight
Many people take dietary supplements for dietary and health insurance. Some take multinutrient pills daily.
Others take large doses of single nutrients. A valid nutrition assessment by professionals determines the need
for supplements. Self-prescribed supplementation is not advised. There are many arguments for and against
supplements.
A. Arguments for Supplements
1. Correct Overt Deficiencies.
2. Support Increased Nutrient Needs.
3. Improve Nutrition Status.
4. Improve the Body’s Defenses.
5. Reduce Disease Risks.
6. Who Needs Supplements?
a. People with nutritional deficiencies.
e. People in certain stages of the life cycle.
1. Infants need iron and fluoride.
2. Women of childbearing age and pregnant women need folate and iron.
3. Elderly need vitamins B12 and D.
f. Those with limited sun exposure and poor milk intake need vitamin D.
B. Arguments against Supplements
1. Toxicity.
4. False Sense of Security.
5. Other Invalid Reasons:
a. Belief that food supply and soil contain inadequate nutrients.
6. Bioavailability and Antagonistic Actions
a. Micronutrients from supplements compete for absorption – e.g. zinc, iron, calcium, magnesium.
b. Some can interfere with each other’s metabolism – e.g. beta-carotene, vitamin E.
C. Selection of Supplements IM WS 10–3, CA 10–8, 10-9
1. What form do you want?
2. What vitamins and minerals do you need?
3. Are there misleading claims?
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a. Ignore organic or natural claims.
g. Internet information is not closely regulated.
4. What about the cost?
D. Regulation of Supplements
1. Nutritional labeling for supplements is required.
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
Case Study5
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 has 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. How would you explain the function of vitamins in response to Samuel’s request?
2. What are some indications that Samuel’s diet may be low in thiamin?
3. Using information from Figure 10-4, list one or two good sources of thiamin from each of the foods groups that
Samuel could add to his diet.
4. What other vitamins would you suspect to be deficient in Samuel’s diet? Why?
5. Based on his medical and diet history, explain why Samuel may be at 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. They do not provide energy but
assist the enzymes that release energy from carbohydrates, fats, and proteins in foods.
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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 10-2: 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: What Vitamin Am I?
Key concept: Characteristics of vitamins Class size: Any
Materials needed: Index cards/slips of paper with vitamin names (prepared prior to class time), tape
Instructions: Before class, prepare “Post–its,” index cards, or slips of paper by writing one water-soluble vitamin on
each paper or card. (You may also include other terms that appear in the chapter.) Tape an index card on the back of
each student. The goal of the activity is for students to find out what vitamins are written on their backs.
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Classroom Activity 10-5: 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.
Example:
Vitamin Vocabulary Worksheet
1. A deficiency of _________ produces diarrhea, dermatitis, and dementia.
Niacin
Classroom Activity 10-7: 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 10-9: Vitamin/Mineral Supplement Evaluation
Key concept: Choosing a dietary supplement Class size: Any
Materials needed: 1 copy of Worksheet 10-3 for each student
Instructions: Distribute Worksheet 10-3 (Vitamin/Mineral Supplement Evaluation Form). Instruct students to select
a vitamin supplement and evaluate the supplement using the form. Issues that will be covered include cost,
completeness, percent of RDA/AI (low amounts or dangerously high amounts), presence of unnecessary nutrients or
ingredients, and advertising terms such as “natural,” “organic,” “chelated,” “no sugar,” or “stress–reliever.” Have
students share their evaluations with the class.
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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
Critical Thinking Questions8
These questions will also be posted to the book’s website so that students can complete them online and e-mail their
answers to you.
1. Outline the differences between macronutrients (carbohydrates, fats, and proteins) and vitamins.
Answer: There are many to discuss:
Structure: Vitamins are individual units, as opposed to macronutrients, which can be broken down further into
individual units that provide energy. Vitamins do not provide energy per se but are involved in metabolic
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2. The B vitamins are very important in many critical functions of the body, yet many clients perceive B vitamins
in a much critical manner. How would you educate clients about the importance of B vitamins and their critical
functions without confusing them?
Answer: The B vitamins have many different roles in reactions within the metabolic pathways.
Thiamin: This water-soluble vitamin is a vital part of thiamin pyrophosphate, a coenzyme that is very important
for energy metabolism. This vitamin is very heat liable, and a deficiency causes beriberi. Thiamin is available in
many foods, including fruits, vegetables, and meats.
Biotin: This B vitamin also plays an important role in carbohydrate metabolism within the TCA cycle. While
deficiencies are rare, there are instances where consumption of egg whites can cause a deficiency of biotin.
Biotin is found in protein sources such egg yolks, liver, and soybeans.
Pantothenic Acid: Another important vitamin in metabolic pathways is pathothenic acid. This vitamin is part of
coenzyme A and thus part of the TCA cycle. While the needs for this vitamin are not large, a deficiency can
cause many issues in neurologic function. Sources of pantothenic acid are proteins and whole grains.
3. Discuss the roles of vitamin C.
Answer: Vitamin C serves in a multitude of roles within the body. It has long been known to relieve the
symptoms of scurvy, which was rampant in the British Navy when sailors did not receive any citrus fruits. The
role of ascorbic acid was later discovered. From that time, scientists were aware of the need for vitamin C.