Nutrition: Concepts & Controversies, 12e Sizer/Whitney Chapter 7 The Vitamins Nutrition: Concepts & Controversies, 12e Sizer/Whitney

Definition and Classification of Vitamins Essential, noncaloric, organic Role of vitamins Vitamin precursors Classes Absorption Roles

Vitamin Names

Characteristics of the Fat-Soluble and Water-Soluble Vitamins

The Fat-Soluble Vitamins A, D, E, and K Food sources Storage Toxicity Deficiency Roles within the body

Vitamin A Precursor Active forms in the body Food sources Beta-carotene Active forms in the body Retinol Retinal Retinoic acid Food sources

Vitamin A Deficiency and Toxicity

Vitamin A – Snapshot

Beta-Carotene Plant-based foods Macular degeneration Colorful groups Macular degeneration Dietary antioxidant Measuring beta-carotene Retinol activity equivalents (RAE) Toxicity Food sources

Vitamin D Body can synthesize all it needs Transformation Sunlight Transformation Liver and kidneys Estimated deficiency prevalence

Vitamin D Ultraviolet B light rays Sunbathing risks Sunscreen Cholesterol Sunbathing risks Sunscreen Exposure times Intake recommendations Food sources

Factors Affecting Vitamin D Synthesis

Vitamin D - Snapshot

Vitamin E Roles of vitamin E Deficiency Toxicity Recommendations Antioxidant Deficiency Symptoms Toxicity Dietary intake vs. supplemental intake Recommendations Food source

Free-Radical Damage and Antioxidant Protection

Vitamin E – Snapshot

Vitamin K – Snapshot

The Water-Soluble Vitamins Dissolve in water Absorption Transport Excretion Sources Food Supplements

Vitamin C Roles Deficiency symptoms Connective tissues Antioxidant Collagen Antioxidant Protects iron Prooxidant Deficiency symptoms Scurvy

Vitamin C – Snapshot

The 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 Action

Some Roles of the B Vitamins in Metabolism: Examples

Thiamin Energy metabolism of all cells Nerve cell membranes Deficiency Beriberi Alcohol abuse DRI recommendation Food sources

Thiamin Snapshot

Riboflavin Role in energy metabolism of all cells Deficiencies Examples Destruction of vitamin UV light Irradiation Heat

Riboflavin Snapshot

Niacin Participates in energy metabolism Deficiency Toxicity Pellagra Physician administration “Niacin flush”

Niacin Snapshot

Folate Helps synthesize DNA Deficiency Interaction with medications Normal metabolism of several amino acids Deficiency Causes Outcomes of deficiency Anemia, diminished Immunity, abnormal digestive function Cancer risk Interaction with medications

Folate Snapshot

Vitamin B12 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 B12 Snapshot

Vitamin B6 Snapshot

Some Valid Reasons for Taking Supplements

Arguments Against Taking Supplements Food rarely causes nutrient imbalances or toxicities Toxicity Supplement contamination Lift-threatening misinformation Unknown needs False sense of security Whole foods are best