Vitamin

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The Vitamins

Chapter 7

Frances Sizer and Ellie Whitney, Nutrition: Concepts and

May not be scanned, copied or duplicated, or posted to a publicly

accessible website, in whole or in part.

Chapter 7. The Vitamins. Learning Objectives

▪List the fat-soluble and water-soluble vitamins, and describe how solubility affects the absorption, transport, storage, and excretion of each type.

▪Define the term antioxidant, and name the vitamins that act as antioxidants in the body.

▪Discuss the roles of B vitamins in body tissues, and explain in a general way how B vitamins assist with energy metabolism.

▪Suggest foods that can help to ensure adequate vitamin intakes without providing too many calories.

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Definition and Classification of Vitamins

• Vitamins

• Essential, noncaloric, and organic nutrient

• Needed in tiny amounts

• Role of vitamins

• Vitamin precursors

• Transform into active vitamin forms inside the body

• Classes of vitamins

• Fat-soluble

• Water-soluble

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Table 7.1: Vitamin Namesa

Fat-Soluble Vitamins Water-Soluble Vitamins

Vitamin A B vitamins: Thiamin (B1), riboflavin (B2), niacin (B3), folate, vitamin B12, vitamin B6, biotin, and pantothenic acid

Vitamin D Vitamin C

Vitamin E N A

Vitamin K N A

aVitamin names established by the International Union of Nutritional Sciences Committee on Nomenclature. Other names are listed in Tables 7.8 and 7.9 (pages 254–258).

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Table 7.2: Characteristics of the Fat-Soluble and Water-Soluble Vitamins (Slide 1 of 2)

Although each vitamin has unique functions and features, a few generalizations about the fat-soluble and water-soluble vitamins can aid understanding.

Characteristics Fat-Soluble Vitamins:

Vitamins A, D, E, and K

Water-Soluble Vitamins:

B Vitamins and Vitamin C

Absorption Absorbed like fats, first

into the lymph and then

into the blood.

Absorbed directly into the

blood.

Transport and

Storage

Travel with protein carriers

in watery body fluids;

stored in the liver or fatty

tissues.

Travel freely in watery

fluids; most are not stored

in the body.

Excretion Not readily excreted; tend

to build up in the tissues.

Readily excreted in the

urine.

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Table 7.2: Characteristics of the Fat-Soluble and Water-Soluble Vitamins (Slide 2 of 2)

Characteristics Fat-Soluble Vitamins:

Vitamins A, D, E, and K

Water-Soluble Vitamins:

B Vitamins and Vitamin C

Toxicity Toxicities are likely from

supplements but occur

rarely from food.

Toxicities are unlikely but

possible with high doses

from supplements.

Requirements Needed in periodic doses

(weekly or even monthly)

depending on the extent of

body stores.

Needed frequently (even

daily) because the body

does not store most of

them to any extent.

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The Fat-Soluble Vitamins

• Vitamins A, D, E, and K

• Found in fats and oils of foods

• Storage

• Fat-soluble vitamins do not need to be consumed every day

• Excess consumption can lead to toxic buildup

• Deficiencies

• Play diverse roles within the body

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Vitamin A

• Plant-derived precursor

• Beta-carotene

• Three active forms in the body

• Retinol, stored in liver

• Retinal

• Retinoic acid

• Food sources

• Animals

• Plants

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Roles of Vitamin A and Consequences of Deficiency (Slide 1 of 3)

• Eyesight

• Maintenance of healthy cornea

• Process of light perception at

retina

• Vitamin A is a part of rhodopsin

molecule

• Night blindness

• Deficiency of vitamin A

• Lag in recovery of night vision

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Figure 7.2: Night Blindness

In dim light, you can see what’s ahead on the road.

Normally, you quickly recover and can see the details again in a few seconds.

A flash of bright light, such as headlights, momentarily blinds you as the pigment in the retina is bleached.

With inadequate vitamin A, you do not recover but remain blind for many seconds or minutes. This is night blindness.iStock.com/ollo

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Roles of Vitamin A and Consequences of Deficiency (Slide 2 of 3)

• Xerophthalmia and blindness

• Keratinization of cornea

• Xerosis

• Xerophthalmia

• Gene regulation

• Retinoic acid

• Essential for epithelial tissue

• Cell differentiation

• Deficiency increases vulnerability

to infection

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Roles of Vitamin A and Consequences of Deficiency (Slide 3 of 3)

• Immune function

• Vitamin A is known as an “anti-infective” vitamin

• Downward spiral of malnutrition and infection can occur in vitamin

A–deficient children

• Reproduction and growth

• Essential for normal reproductive processes in men and women

• Indispensable for growth in children

• Deficiency around the world

• W H O and UNICEF are working to eliminate vitamin A deficiency

around the world

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Vitamin A Toxicity

• Toxicity

• Can be caused by excess intake of supplements and fortified

foods

• Symptoms

• Higher-risk groups

• Pregnant women

• Children

• Misinformed adolescents

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Figure 7.4: Vitamin A Deficiency and Toxicity

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Vitamin A Recommendations and Sources

• D R I of active vitamin A based on body weight

• 900 μg/day for men; 700 μg/day for women

• Tolerable Upper Intake Level (U L) of 3,000 micrograms/day

• Steer clear of supplements to avoid toxicity

• Richest sources

• Liver and fish

• Consume liver in moderation

• Milk, milk products, and fortified foods

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Table 7.3: Sources of Active Vitamin A (Slide 1 of 2)

Vitamin A from highly fortified foods and other rich sources

can add up. The U L for vitamin A is 3,000 micrograms (μg)

per day.

Source Vitamin A Levels

High-potency vitamin pill 3,000 μg

Calf’s liver, 1 o z cooked 2,300 μg

Regular multivitamin pill 1,500 μg

Vitamin gumball, 1 1,500 μg

Chicken liver, 1 o z cooked 1,400 μg

“Complete” liquid

supplement drink, 1 serving

350–1,500 μg

Instant breakfast drink, 1

serving

600–700 μg

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Table 7.3: Sources of Active Vitamin A (Slide 2 of 2)

Source Vitamin A Levels

Cereal breakfast bar, 1 350–400 μg

“Energy” candy bar, 1 350 μg

Milk, 1 c 150 μg

Vitamin-fortified cereal, 1

serving

150 μg

Margarine, 1 teaspoon 55 μg

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Table 7.4: Functional Group of Antioxidants

Functional Group of Antioxidants

Key antioxidant vitamins: Beta-carotene, vitamin E, and

vitamin C

A key antioxidant mineral: Selenium

Many antioxidant phytochemicals

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Beta-Carotene (Slide 1 of 2)

• Dietary antioxidant

• Present in plant-based foods

• Colorful groups

• Orange-colored fruits and vegetables

• Dark green vegetables

• Carotenoids: Chemical relatives of beta-carotene

• Deficiency causes macular degeneration

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Beta-Carotene (Slide 2 of 2)

• Measuring beta-carotene

• Retinol activity equivalents (R A E)

• Sometimes expressed in I U (international units)

• Toxicity

• Food sources

• Richest source: Sweet potato

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Figure 7.5: Excess Beta-Carotene Symptom: Discoloration of the Skin

James Stevenson/Science Source

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Snapshot 7.1: Vitamin A and Beta-Carotene

*These foods provide 10% or more of the vitamin A Daily Value in a serving. For a 2,000-cal diet, the D V is 900 μg/day.

aVitamin A recommendations are expressed in retinol activity equivalents (R A E).

bThis food contains preformed vitamin A.

cThis food contains the vitamin A precursor, beta-carotene.

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Vitamin D

• Not an essential nutrient

• Body can synthesize all it needs using sunlight

• Estimated deficiency prevalence at 16% in the United

States

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Roles of Vitamin D

• Calcium regulation

• Acts at three body locations

to raise calcium level

• Skeleton

• Digestive tract

• Kidneys

• Other roles

• Hormone

• Acts at the genetic level

• Further research on roles

ongoing

Functional Group for Bone Health

Key vitamins: Vitamin D, vitamin K, and vitamin C

Key minerals: Calcium, phosphorous, magnesium, and fluoride

Key energy nutrient: Protein

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Too Little Vitamin D—A Danger to Bones

• Deficiency

• Rickets

• Early in life

• Recommendations for prevention

• Osteomalacia

• Deficiency in adults

• Recommendations for prevention

• Osteoporosis

• Groups to be concerned

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Figure 7.6: Rickets

This child has the bowed legs of the vitamin D–deficiency disease, rickets.

Biophoto Associates/Science Source

This child displays beaded ribs, a symptom of rickets.

Photo Courtesy of Dr. Norman Carvalho at Children’s Healthcare of Atlanta

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Too Much Vitamin D—A Danger to Soft Tissues

• Most potentially toxic vitamin

• Increases blood calcium concentrations

• Kidney and heart failure

• Risk of high doses

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Vitamin D from Sunlight

• Ultraviolet rays

• Cholesterol compound

• Role of the liver and kidneys

• Skin pigments

• Factors that interfere with vitamin D synthesis

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Table 7.6: Factors Affecting Vitamin D Synthesis (Slide 1 of 2)

Factor Effect on Vitamin D Synthesis

Advanced age With age, the skin loses some of its capacity to

synthesize vitamin D.

Air pollution Particles in the air screen out the sun’s rays.

City living Tall buildings block sunlight.

Clothing Most clothing blocks sunlight.

Cloudy skies Heavy cloud cover reduces sunlight penetration.

Geography Sunlight exposure is limited

• October through March at latitudes above 43 degrees

(most of Canada)

• November through February at latitudes between 35

and 43 degrees (many U.S. locations)

In locations south of 35 degrees (much of the southern

United States), direct sun exposure is sufficient for

vitamin D synthesis year-round.

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Table 7.6: Factors Affecting Vitamin D Synthesis (Slide 2 of 2)

Factor Effect on Vitamin D Synthesis

Homebound Living indoors prevents sun exposure.

Season Warmer seasons of the year bring more direct sun rays.

Skin pigment Darker-skinned people synthesize less vitamin D per

minute than lighter-skinned people.

Sunscreen Proper use reduces or prevents skin exposure to sun’s

rays.

Time of day Midday hours bring maximum direct sun exposure.

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Vitamin D Recommendations and Food Sources

• Recommendations

• Need remains steady throughout life

• U L for adults for all ages is 100 micrograms

• Adequate intake of calcium required

• Food sources

• Milk

• Mushrooms

• Fortified products

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Snapshot 7.2: Vitamin D

*These foods provide 10% or more of the vitamin D Daily Value in a serving. For a 2,000-cal diet, the D V is 20 μg/day.

aAverage value.

bAvoid prolonged exposure to sun.

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Vitamin E (Slide 1 of 4)

• Tocopherol

• Tocopherol compounds: Alpha, beta, gamma, and delta

• Alpha-tocopherol is the gold standard

• Roles of Vitamin E

• Antioxidant guarding against oxidative damage by free radicals

• Theory of oxidative stress

• Reduced inflammation

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Vitamin E (Slide 2 of 4)

• Deficiencies occur in:

• People with diseases that cause fat malabsorption

• Premature babies

• Erythrocyte hemolysis

• Symptoms of vitamin E deficiency

• Loss of muscle coordination

• Loss of normal reflexes

• Impaired vision and speech

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Figure 7.7: Free-Radical Damage and Antioxidant Protection

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Vitamin E (Slide 3 of 4)

• Toxicity

• Symptoms

• Dietary intake versus

supplemental intake

• Recommendations

• D R I is 15 milligrams a day

for adults

• Smokers may have higher

needs

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Vitamin E (Slide 4 of 4)

• Food sources

• Vitamin E is readily destroyed

by heat

• Best sources: Raw oils and

lightly processed foods

Monkey Business Images/Shutterstock.com

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Snapshot 7.3: Vitamin E

*These foods provide 10% or more of the vitamin E Daily Value in a serving. For a 2,000-cal diet, the D V is 22 I U or 15 mg/day.

aCooking destroys vitamin E.

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Vitamin K (Slide 1 of 2)

• Roles

• Blood clotting

• Bone-protein synthesis

• Drug interference

• Deficiency

• Dangerous in newborn infants

• Toxicity

• Causes jaundice

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Vitamin K (Slide 2 of 2)

• Requirements

• 120 μg/day for men

• 90 μg/day for women

• Sources

• Nonfood source: Intestinal

bacteria

• Supplements

• Dark green, leafy vegetables

• Fortified foods Art Directors & TRIP/Alamy Stock Photo

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Snapshot 7.4: Vitamin K

*These foods provide 10% or more of the vitamin K Daily Value in a serving. For a 2,000-cal diet, the D V is 120 μg/day.

aAverage value.

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The Water-Soluble Vitamins

• Dissolve in water

• Absorption

• Excretion

• Not stored in the body

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Think Fitness: Vitamins for Athletes

• Competitive athletes who choose their diets with

reasonable care almost never need nutrient supplements

• The need for energy to fuel exercise requires that people

eat extra calories for food

• If the food consumed is packed with nutrients, then the extra

vitamins needed to support the activity flow naturally into the body

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Vitamin C (Slide 1 of 3)

• Also known as ascorbic acid

• Roles

• Connective tissues

• Enzymes involved in the formation and maintenance of collagen

• Carnitine and hormone production

• Antioxidant activity

• Protects iron and promotes its absorption

• Prooxidant outside the body

• Does it cure a common cold?

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Vitamin C (Slide 2 of 3)

• Deficiency

• Scurvy

• Symptoms

• Smokers and people with low incomes are at risk

• Toxicity

• Safe range of intake: 10 milligrams/day to 2,000 milligrams/day

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Figure 7.11: Scurvy Symptoms—Gums and Skin

Vitamin C deficiency causes the breakdown of collagen, which supports the teeth.

Lester V. Bergman/Encyclopedia/Corbis

Small pinpoint hemorrhages (red spots) appear in the skin, indicating that invisible internal bleeding may also be occurring.

Dr. P. Marazzi/Science Source

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Vitamin C (Slide 3 of 3)

• Recommendations

• 90 milligrams for men and 75 milligrams for women

• Effects of tobacco use and physical stressors

• Food sources

• Fresh fruits and vegetables

• White potatoes

• Sweet potatoes

• Destruction of vitamin C

• Heat and oxygen

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Figure 7.12: Vitamin C Tower of Recommendations

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Snapshot 7.5: Vitamin C

*These foods provide 10% or more of the vitamin C Daily Value in a serving. For a 2,000-cal diet, the D V is 90 mg/day.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

The B Vitamins in Unison (Slide 1 of 2)

• Function as parts of coenzymes

• Coenzyme combines with an enzyme to activate it

• Shape of each coenzyme predestines it to accomplish just one

kind of job

• Role in energy metabolism

• Help the body use the energy-yielding nutrients for energy

• Aid in cell multiplication

• Red blood cells

• Cells of the digestive tract

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Figure 7.13: Coenzyme Action

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Figure 7.14: Some Roles of the B Vitamins in Metabolism: Examples

The purpose of this figure is to show a few of the many tissue

functions that require a host of B vitamin–dependent enzymes

working together in harmony. The B vitamins work in every

cell, and this figure displays less than a thousandth of what

they actually do. Every B vitamin is part of one or more

coenzymes that make possible the body’s chemical work. For

example, the niacin, thiamin, and riboflavin coenzymes are

important in the energy pathways. The folate and vitamin B12 coenzymes are necessary for making RNA and DNA and thus

new cells. The vitamin B6 coenzyme is necessary for

processing amino acids and therefore protein. Although many

other relationships are also critical to metabolism, this figure

does not attempt to teach intricate biochemical pathways or

names of B vitamin–containing enzymes.

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The B Vitamins in Unison (Slide 2 of 2)

• Deficiencies

• Every cell is affected

• Symptoms

• Deficiency of any one B

vitamin is rare as people

consume food that contain

mixtures of nutrients SPL/Science Source

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Thiamin

• Plays a critical role in the energy metabolism of all cells

• Occupies a special site on nerve cell membranes

• Deficiency • Beriberi

• Forms: Wet and dry

• Wernicke-Korsakoff syndrome

• Symptoms

• D R I recommendation • 1.2 milligrams/day for men and

1.1 milligrams/day for women

SPL/Science Source

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Snapshot 7.6: Thiamin

*These foods provide 10% or more of the thiamin Daily Value in a serving. For a 2,000-cal diet, the DV is 1.2 mg/day.

aSevere thiamin deficiency is often related to heavy alcohol consumption.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Riboflavin

• Plays a role in the energy metabolism pathways of all

cells

• Deficiencies

• Symptoms similar to those of thiamin deficiency

• Destroyed by ultraviolet light and irradiation

• Riboflavin is heat stable

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Snapshot 7.7: Riboflavin

*These foods provide 10% or more of the riboflavin Daily Value in a serving. For a 2,000-cal diet, the D V is 1.3 mg/day.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Niacin (Slide 1 of 2)

• Participates in energy metabolism

• Deficiency

• Pellagra

• Occurs among poorly nourished people

and particularly among those with

alcohol addiction

• Symptoms: Diarrhea, dermatitis,

dementia, and death

• Used in the past to improve blood

lipids

• Common side effect: “Niacin flush” Dr M.A. Ansary/Science Source

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Niacin (Slide 2 of 2)

• Recommendations

• Amino acid tryptophan can prevent pellagra

• Amount of niacin in a diet is stated in terms of niacin equivalents

(N E)

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Snapshot 7.8: Niacin

These foods provide 10% or more of the niacin Daily Value in a serving. For a 2,000-cal diet, the D V is 16 mg/day. The D V values are for preformed niacin, not niacin equivalents.

aNiacin D R I values are expressed in niacin equivalents (N E); the Tolerable Upper Intake Level refers to preformed niacin.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Folate (Slide 1 of 3)

• Roles

• DNA synthesis

• Participation in the metabolism of vitamin B12 and many amino

acids

• Outcomes of deficiency

• Anemia, diminished immunity, abnormal digestive function, and

increased risk of cancer

• Folate deficiency is related to the anemia of vitamin B12

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Folate (Slide 2 of 3)

• Most likely to interact with

medications

• Consuming enough folate

during pregnancy can help

reduce the risk of:

• Neural tube defects (N T D)

and other related birth defects

• Cleft lip

• Miscarriages Biophoto Associates/Science Source

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Figure 7.19: Effect of Folic Acid Fortification on the Prevalence of Neural Tube Defects

Far fewer neural tube defects have occurred since countries began

fortifying their food supplies with folate.

Source: Centers for Disease Control and Prevention, Folic acid: Birth defects COUNT, (2017), available at www.cdc.gov/ncbddd/birthdefectscount/data.html.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Folate (Slide 3 of 3)

• Folate enrichment

• Absorbable synthetic form: Folic acid

• Toxicity

• U L is set at 1,000 micrograms/day for adults

• May mask a subclinical deficiency of vitamin B12

• Recommendations: 400 micrograms/day

• Food sources of folate

• Leafy green vegetables and raw or lightly cooked vegetables

• Dietary folate equivalent (D F E) converts all forms of

folate to micrograms that are equivalent to the folate in

foods

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Snapshot 7.9: Folate

*These foods provide 10% or more of the folate Daily Value in a serving. For a 2,000-cal diet, the D V is 400 μg/day.

aFolate recommendations are expressed in dietary folate equivalents (D F E). Note that for natural folate sources, 1 μg = 1 D F E; for enrichment sources, 1 μg = 1.7 D F E.

bSome highly enriched cereals may provide 400 μg or more in a serving.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Vitamin B12 (Slide 1 of 2)

• Closely related to folate

• Depend on each other for activation

• Functions as part of coenzymes in cell replication

• Maintains sheaths around nerve fibers

• Deficiency

• Anemia

• Presence of large immature red blood cells

• Creeping paralysis

• General malfunctioning of nerves and muscles

• Impairment of mental functioning in the elderly, which worsens

dementia

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Vitamin B12 (Slide 2 of 2)

• Vitamin B12 malabsorption

• Caused by a lack of intrinsic factor (pernicious anemia)

• Causes of pernicious anemia

• Inborn gene defect for intrinsic factor

• Intestinal diseases, surgeries, stomach infections

• Intake of common diabetes drug

• Food sources

• Only of animal origin

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Figure 7.20: Anemic and Normal Blood Cells

Carolina Biological/Visuals Unlimited

Blood cells of pernicious anemia. The cells are larger than normal and irregular in shape.

Ed Reschke/Getty Images

Normal blood cells. The size, shape, and color of these red blood cells show that they are normal.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Snapshot 7.10: Vitamin B12

*These foods provide 10% or more of the vitamin B12 Daily Value in a serving. For a 2,000-cal diet, the D V is 2.4 μg/day.

aThe name pernicious anemia refers to the vitamin B12 deficiency caused by a lack of stomach intrinsic factor but not to anemia from inadequate dietary intake.

bLarge cell-type anemia is known as either macrocytic or megaloblastic anemia.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Vitamin B6 (Slide 1 of 2)

• Three active forms: Pyridoxine, pyridoxal, and

pyridoxamine

• Roles

• Conversion of tryptophan to serotonin

• Synthesis of hemoglobin and neurotransmitters

• Maintenance of a normal blood glucose concentration

• Immune function and steroid hormone activity

• Normal development of the fetal brain and nervous system

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Vitamin B6 (Slide 2 of 2)

• Deficiency

• General symptoms, including

anemia and greasy dermatitis

• Toxicity

• Effects seen with consuming 2 g or

• Intake recommendations:

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Snapshot 7.11: Vitamin B6

*These foods provide 10% or more of the vitamin B6 Daily Value in a serving. For a 2,000-cal diet, the D V is 1.7 mg/day.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Biotin and Pantothenic Acid

• Important for energy metabolism

• Biotin

• Coenzyme for carbohydrate, fat, and protein metabolism

• Gene expression

• Intestinal bacteria release absorbable biotin

• No U L set

• Pantothenic acid

• Key coenzyme

• Participate in the synthesis of lipids, neurotransmitters, steroid

hormones, and hemoglobin

• Deficiency diseases rare

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Non–B Vitamins

• Choline

• Conditionally essential nutrient

• Widely supplied by protein-rich foods

• Nonvitamins

• Carnitine

• Inositol

• Lipoic acid

• Other substances claimed to be essential for human

nutrition

• P A B A (para-aminobenzoic acid), bioflavonoids, ubiquinone, and

vitamins B15 and B17

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Choosing Foods Rich in Vitamins

• Use search tools

• U S D A’s What’s in the Foods You Eat

• U S D A Food Composition Databases

• Make food choices with reasonable care

• A variety of foods works best

• Recommended amounts of fruit and vegetables cover needs

amply

• Variety of nutrient-dense foods is better than foods that provide

isolated nutrients

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Controversy 7: Vitamin Supplements: What Are the Benefits and Risks? (Slide 1 of 2)

• Arguments in favor of taking supplements

• People prone to vitamin deficiencies require supplements

• Habitual dieters

• Elderly people with diminished appetite

• People with wasting illnesses

• People who omit entire food groups

• People who lack knowledge or money to eat properly

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Controversy 7: Vitamin Supplements: What Are the Benefits and Risks? (Slide 2 of 2)

• At certain life stages, people may have increased nutrient

needs

• Menstruation

• Pregnancy and lactation

• Newborns

• Appetite and physical stress can impair nutrient status

• Addiction to alcohol and drugs

• Medication use

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Table C7:1: Some Valid Reasons for Taking Supplements (Slide 1 of 2)

These people may need supplements:

• People with nutrient deficiencies.

• Women who are capable of becoming pregnant (supplemental or

enrichment sources of folic acid are recommended to reduce risk of

neural tube defects in infants).

• Pregnant women and lactating women (they may need iron and folate).

• Newborns (they are routinely given a vitamin K dose).

• Infants (they may need various supplements; see Chapter 13).

• People who undergo weight-loss surgery (incurs nutrient malabsorption).

• Those who are lactose intolerant (they need calcium to forestall

osteoporosis).

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Table C7:1: Some Valid Reasons for Taking Supplements (Slide 2 of 2)

These people may need supplements:

• Habitual dieters (they may eat insufficient food).

• Elderly people often benefit from some of the vitamins and minerals in a

balanced supplement (they may choose poor diets, have trouble chewing, or

absorb or metabolize nutrients inefficiently; see Chapter 14).

• People living with HIV or other wasting illnesses (they lose nutrients faster

than foods can supply them).

• Those addicted to drugs or alcohol (they absorb fewer and excrete more

nutrients; nutrients cannot undo damage from drugs or alcohol).

• Those recovering from surgery, burns, injury, or illness (they need extra

nutrients to help regenerate tissues).

• Strict vegetarians (vegans may need vitamin B12, vitamin D, iron, and zinc).

• People taking medications that interfere with the body’s use of nutrients.

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Arguments against Taking Supplements (Slide 1 of 2)

• Food rarely causes nutrient imbalances or toxicities

• Supplement users are more likely to have excessive intakes of

certain nutrients, notably iron, zinc, vitamin A, and niacin

• Supplement contamination and safety

• Under current Dietary Supplement Health and Education Act, the F

D A has little control over supplement sales

• Contents of multivitamin and mineral

supplements may vary from those

stated on the label

Alex Segre/Alamy Stock Photo

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Arguments against Taking Supplements (Slide 2 of 2)

• Life-threatening misinformation

• False sense of security

• Whole foods are best for nutrients

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Can Supplements Prevent Chronic Diseases?

• Vitamin D and cancer

• Evidence does not support claims that vitamin D supplements

prevent cancer from occurring

• Antioxidant supplements

• Evidence does not support a role for supplements against chronic

diseases

• Vitamin E and chronic disease

• Neither help nor harm observed with vitamin E supplementation

• Beta-carotene

• Rise in lung cancer with supplement intake in smokers

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

S O S: Selection of Supplements

• Choose a type

• Read labels

• Target your needs

• Choose appropriate doses

• Go for quality

• Avoid marketing traps

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Some Invalid Reasons for Taking Supplements

Invalid Reasons for Taking Supplements

You fear that foods grown on today’s soils lack nutrients (a common false

statement made by sellers of supplements).

You feel tired and falsely believe that supplements can provide energy.

You hope that supplements can help you cope with stress.

You wish to build up your muscles faster or without physical activity.

You want to prevent or cure self-diagnosed illnesses.

You hope excess nutrients will produce unnamed mysterious beneficial

reactions in your body.

People who should never take supplements without a physician’s approval include those with kidney or liver ailments (they are susceptible to toxicities), those taking medications (nutrients can interfere with their actions), and smokers (who should avoid products with beta-carotene).

May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Figure C7.2: How to Read a Supplement Label

BirchTree/Alamy stock photo Anne Dowie