Chapter 7Chapter 7

The VitaminsThe Vitamins

Nutrition: Concepts & Controversies, 12e Nutrition: Concepts & Controversies, 12e Sizer/WhitneySizer/Whitney

Learning ObjectivesLearning Objectives

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

Explain how vitamins and minerals work in combination to maintain the health of the bones.

Name some functions of vitamin D not associated with the bones.

Learning ObjectivesLearning Objectives

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.

Present arguments both for and against vitamin fortification of foods.

Learning ObjectivesLearning Objectives

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

Justify this statement: “It is better to get vitamins from food than from supplements.”

List some valid reasons why supplements may be required by some people.

Definition and Classification of Definition and Classification of VitaminsVitamins

Vitamin Essential, noncaloric, organic

Role of vitamins Vitamin precursors Classes

Absorption Roles

Vitamin NamesVitamin Names

Characteristics of the Fat-Soluble Characteristics of the Fat-Soluble and Water-Soluble Vitaminsand Water-Soluble Vitamins

The Fat-Soluble VitaminsThe Fat-Soluble Vitamins

A, D, E, and K Food sources

Storage Toxicity

Deficiency Roles within the body

Vitamin AVitamin A

Precursor Beta-carotene

Active forms in the body Retinol Retinal Retinoic acid

Food sources

Vitamin A – Roles and DeficiencyVitamin A – Roles and Deficiency

Gene regulation Retinoic acid

Eyesight Process of light perception Maintenance of healthy cornea Rhodopsin molecule

An EyeAn Eye

Vitamin A – Roles and DeficiencyVitamin A – Roles and Deficiency

Night blindness Deficiency

Xerophthalmia and blindness Keratinization

Deficiency

Cell differentiation Immune function Growth

Vitamin A – Deficiency and Vitamin A – Deficiency and ToxicityToxicity

Deficiency Worldwide problem

BlindnessHIV

Toxicity Symptoms food sources

Liver

Vitamin A – Deficiency and Vitamin A – Deficiency and ToxicityToxicity

Toxicity Supplements Higher risk groups

Recommendations DRI recommendation based on body weight

Food sources Animal origin

Liver Plant origin

Vitamin A Deficiency and ToxicityVitamin A Deficiency and Toxicity

Vitamin A – Snapshot Vitamin A – Snapshot

Beta-CaroteneBeta-Carotene

Plant-based foods Colorful groups

Macular degeneration Dietary antioxidant Measuring beta-carotene

Retinol activity equivalents (RAE) Toxicity Food sources

Excess Beta-Carotene Symptom: Excess Beta-Carotene Symptom: Discoloration of the SkinDiscoloration of the Skin

Vitamin DVitamin D

Body can synthesize all it needs Sunlight

Transformation Liver and kidneys

Estimated deficiency prevalence

Vitamin D – Roles Vitamin D – Roles

Bone integrity Hormone Dangers with

deficiency

Vitamin D – Too Little, Too MuchVitamin D – Too Little, Too Much

Deficiency Rickets

Recommendations for prevention Osteomalacia

Recommendations

Toxicity Signs of toxicity

RicketsRickets

Vitamin DVitamin D

Ultraviolet B light rays Cholesterol

Sunbathing risks Sunscreen

Exposure times Intake

recommendations Food sources

Factors Affecting Vitamin D Factors Affecting Vitamin D Synthesis Synthesis

Vitamin D - SnapshotVitamin D - Snapshot

Vitamin EVitamin E

Roles of vitamin E Antioxidant

Deficiency Symptoms

Toxicity Dietary intake vs. supplemental intake

Recommendations Food source

Free-Radical Damage and Free-Radical Damage and Antioxidant ProtectionAntioxidant Protection

Vitamin E – Snapshot Vitamin E – Snapshot

Vitamin KVitamin K

Roles Blood clotting Bone proteins

Deficiency Toxicity

Jaundice Requirements

Sources

Vitamin K – SnapshotVitamin K – Snapshot

The Water-Soluble VitaminsThe Water-Soluble Vitamins

Dissolve in water Absorption Transport Excretion

Sources Food Supplements

Vitamin CVitamin C

Roles Connective tissues

Collagen Antioxidant

Protects ironProoxidant

Deficiency symptoms Scurvy

Scurvy Symptoms – Gums and Scurvy Symptoms – Gums and SkinSkin

Vitamin CVitamin C

Toxicity Safe doses

Recommendations Tobacco use Physical stressors

Food sources Destruction of vitamin

C

Vitamin C – Snapshot Vitamin C – Snapshot

The B Vitamins in UnisonThe B Vitamins in Unison

Function as part of coenzymes Combines with enzyme to activate it Coenzyme shape

Roles in metabolism Help the body use the energy-yielding

nutrients for energy Cell multiplication

Coenzyme ActionCoenzyme Action

Some Roles of the B Vitamins in Some Roles of the B Vitamins in Metabolism: ExamplesMetabolism: Examples

The B Vitamins in UnisonThe B Vitamins in Unison

Deficiencies Every cell is affected Symptoms Rarely are isolated deficiencies

Thiamin Thiamin

Energy metabolism of all cells

Nerve cell membranes Deficiency

Beriberi Alcohol abuse

DRI recommendation Food sources

Thiamin SnapshotThiamin Snapshot

RiboflavinRiboflavin

Role in energy metabolism of all cells Deficiencies

Examples Destruction of vitamin

UV light Irradiation Heat

Riboflavin SnapshotRiboflavin Snapshot

NiacinNiacin

Participates in energy metabolism

Deficiency Pellagra

Toxicity Physician

administration “Niacin flush”

Niacin SnapshotNiacin Snapshot

FolateFolate

Helps synthesize DNA Normal metabolism of several amino acids

Deficiency Causes Outcomes of deficiency

Anemia, diminished Immunity, abnormal digestive function

Cancer risk

Interaction with medications

FolateFolate

Birth defects Neural tube defects (NTD)

Toxicity UL

Recommendations Food sources of folate

Destruction of folate

Incidence of a Common NTD, Incidence of a Common NTD, Spina Bifida, Over TimeSpina Bifida, Over Time

Folate SnapshotFolate Snapshot

Vitamin BVitamin B1212

Closely related to folate Helps maintain sheaths around nerve fibers Deficiency

May be masked by folic acid intake Pernicious anemia

Vitamin B12 absorption Intrinsic factor

Food sources

Vitamin BVitamin B1212 Snapshot Snapshot

Vitamin BVitamin B66

Roles Participates in over 100 reactions Additional roles

Deficiency General symptoms

Toxicity Intake recommendations

Food sources

Vitamin BVitamin B66 Snapshot Snapshot

Biotin and Pantothenic AcidBiotin and Pantothenic Acid

Important for energy metabolism Biotin

Cofactor for enzymes Gene expression No UL

Pantothenic acid Key coenzyme

Non-B VitaminsNon-B Vitamins

Choline Nonvitamins

Carnitine Inositol Lipoic acid

Vitamin Supplements: Do the Vitamin Supplements: Do the Benefits Outweigh the Risks?Benefits Outweigh the Risks?

Controversy 7

Some Valid Reasons for Taking Some Valid Reasons for Taking SupplementsSupplements

Arguments Against Taking Arguments Against Taking SupplementsSupplements

Food rarely causes nutrient imbalances or toxicities

Toxicity Supplement contamination Lift-threatening misinformation Unknown needs False sense of security Whole foods are best

Can Supplements Prevent Heart Can Supplements Prevent Heart Disease or Cancer?Disease or Cancer?

Oxidative stress Vitamin C

Population studies Animal studies Cell studies Intervention studies

Vitamin E Beta-carotene

Supplements Safety and RisksSupplements Safety and Risks

Safety Food and Drug Association (FDA)

Risks Dangers for your body

Selecting a SupplementSelecting a Supplement

Choose type Read labels Target your needs Choosing doses Quality Avoid marketing

traps