HUN 4296 Nutrition & Health Issues Week 3 Day 1 Vitamins Chp 7 Nutrition: Concepts & Controversies, 12e Sizer/Whitney Chp 7 Nutrition: Concepts & Controversies, 12e Sizer/Whitney

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

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

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

Vitamin A – Roles and Deficiency  Gene regulation  Retinoic acid  Eyesight  Process of light perception  Maintenance of healthy cornea  Rhodopsin molecule

An Eye

Vitamin A – Roles and Deficiency  Night blindness  Deficiency  Xerophthalmia and blindness  Keratinization  Deficiency  Cell differentiation  Immune function  Growth

Vitamin A – Deficiency and Toxicity  Deficiency  Worldwide problem  Blindness  HIV  Toxicity  Symptoms  food sources  Liver

Vitamin A – Deficiency and Toxicity  Toxicity  Supplements  Higher risk groups  Recommendations  DRI recommendation based on body weight  Food sources  Animal origin  Liver  Plant origin

Vitamin A Deficiency and Toxicity

Vitamin A – Snapshot

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

Excess Beta-Carotene Symptom: Discoloration of the Skin

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

Vitamin D – Roles  Bone integrity  Hormone  Dangers with deficiency

Vitamin D – Too Little, Too Much  Deficiency  Rickets  Recommendations for prevention  Osteomalacia  Recommendations  Toxicity  Signs of toxicity

Rickets

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

Factors Affecting Vitamin D Synthesis

Vitamin D - Snapshot

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

Free-Radical Damage and Antioxidant Protection

Vitamin E – Snapshot

Vitamin K  Roles  Blood clotting  Bone proteins  Deficiency  Toxicity  Jaundice  Requirements  Sources

Vitamin K – Snapshot

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

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

Scurvy Symptoms – Gums and Skin

Vitamin C  Toxicity  Safe doses  Recommendations  Tobacco use  Physical stressors  Food sources  Destruction of vitamin C

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

The B Vitamins in Unison  Deficiencies  Every cell is affected  Symptoms  Rarely are isolated deficiencies

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  Pellagra  Toxicity  Physician administration  “Niacin flush”

Niacin Snapshot

Folate  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

Folate  Birth defects  Neural tube defects (NTD)  Toxicity  UL  Recommendations  Food sources of folate  Destruction of folate

Incidence of a Common NTD, Spina Bifida, Over Time

Folate Snapshot

Vitamin B 12  Closely related to folate  Helps maintain sheaths around nerve fibers  Deficiency  May be masked by folic acid intake  Pernicious anemia  Vitamin B 12 absorption  Intrinsic factor  Food sources

Vitamin B 12 Snapshot

Vitamin B 6  Roles  Participates in over 100 reactions  Additional roles  Deficiency  General symptoms  Toxicity  Intake recommendations  Food sources

Vitamin B 6 Snapshot

Biotin and Pantothenic Acid  Important for energy metabolism  Biotin  Cofactor for enzymes  Gene expression  No UL  Pantothenic acid  Key coenzyme

Non-B Vitamins  Choline  Nonvitamins  Carnitine  Inositol  Lipoic acid

Vitamin Supplements: Do the Benefits Outweigh the Risks? Controversy 7

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

Can Supplements Prevent Heart Disease or Cancer?  Oxidative stress  Vitamin C  Population studies  Animal studies  Cell studies  Intervention studies  Vitamin E  Beta-carotene

Supplements Safety and Risks  Safety  Food and Drug Association (FDA)  Risks  Dangers for your body

Selecting a Supplement  Choose type  Read labels  Target your needs  Choosing doses  Quality  Avoid marketing traps