VITAMINS

Definition and Classification Non-caloric organic nutrients Needed in very small amounts Facilitators – help body processes proceed; digestion, absorption, metabolism, growth etc. Some appear in food as precursors or provitamins

Definition and Classification 2 classes Fat soluble: Water soluble:

Definition and Classification Fat soluble vitamins Found in the fats and oils of food. Absorbed into the lymph and carried in blood with protein transporters = chylomicrons. *Stored in liver and body fat and can become toxic if large amounts are consumed.

Definition and Classification Water soluble vitamins Found in vegetables, fruit and grains, meat. Absorbed directly into the blood stream Not stored in the body and toxicity is rare. Alcohol can increase elimination, smoking, etc. cause decreased absorption.

Fat Soluble Vitamins Vitamin A 3 forms: retinol (stored in liver), retinal, retinoic acid Roles in body: Regulation of gene expression Part of the visual pigment rhodopsin, maintains clarity of cornea (yes eating carrots is good for your eyesight) Required for cell growth and division - epithelial cells, bones and teeth Promotes development of immune cells, especially “Natural Killer Cells” Antioxidant

Fat Soluble Vitamins Vitamin A Deficiencies cause: Night blindness, xerophthalmia (keratin deposits in cornea), muscular degeneration. Skin and mucous membrane dryness and infection, keratin deposits. Anemia Developmental defects – bones, teeth, immune system, vision

Fat Soluble Vitamins Vitamin A Toxicities (RetinA/Accutaine, single large doses of supplements, eating excessive amounts of liver) cause: Fragile RBCs, hemorrhage Bone pain, fractures Abdominal pain and diarrhea Blurred vision Dry skin, hair loss Liver enlargement

Fat Soluble Vitamins Vitamin A DRI: 700(women)-900(men) micrograms/day, UL 3000 micrograms/day DRI=DIETRY REFERENCE INTAKE UL= Upper intake level

Snapshot 7-1, p, 219

Fat Soluble Vitamins Vitamin D – precursor is cholesterol, converted by UV from sunlight exposure, therefore is a “non-essential” vitamin. Roles: Increases calcium absorption in bone, intestines, kidney. Promotes bone growth and maintenance. Stimulates maturation of cells – heart, brain, immune system, etc.

Fat Soluble Vitamins Vitamin D Deficiencies: rickets (children), osteomalacia (adults). What are some of the causes of deficiencies? Toxicities (5X DRI) Loss of calcium from bone and deposition in soft tissues. Loss of appetite, nausea and vomiting, psychological depression. Bowed legs – Characteristic of rickets

Beaded ribs – Characteristic of rickets FIGURE 7-5: RICKETS. This child displays the beaded ribs common in rickets. Fig. 7-5b, p. 222

Fat Soluble Vitamins Vitamin D DRI – 5 micrograms/day for ages 19-50, 10 for ages 51-70, 15 for ages >70. Sources, see snapshot 7.2

Snapshot 7-2, p, 223

Fat Soluble Vitamins Vitamin E – tocopherol, *alpha-, beta -, gamma-, and delta- Roles: Antioxidant (protects polyunsaturated fats) Prevention of damage to lungs, RBCs, WBCs (immunity), heart Necessary for normal nerve development

Fat Soluble Vitamins Vitamin E Deficiencies (decreased absorption of fats- liver disease, low fat diets) Premature babies – fragile RBCs (hemolysis) Loss of muscle coordination, vision, immune functions Toxicities (more than 1000 milligrams/day) Increases the effects of anticoagulants (Coumadin, Warfarin)

Fat Soluble Vitamins Vitamin E DRI 15 milligrams/day (alpha-tocopherol) Sources, see snapshot 7.3

Snapshot 7-3, p, 226

Fat Soluble Vitamins Vitamin K – produced by bacteria in large intestine Roles Promotes synthesis of blood clotting proteins (**Interferes with Coumadin) Bone formation Deficiencies are rare but seen in infants, after prolonged antibiotic therapy, and in patients with decreased bile production. Toxicities (>1000 mg/day): rupture of RBCs and jaundice

Fat Soluble Vitamins Vitamin K DRI: 90(women) – 120(men) micrograms/day Sources, see snapshot 7.4

Snapshot 7-4, p, 228

Water Soluble Vitamins 8 B vitamins – Tender Romance Never Fails with 6 to 12 Beautiful Pearls (Thiamin, Riboflavin, Niacin, Folate, B6, B12, Biotin, and Pantothenic acid) Aid in metabolism of and energy release from carbohydrates, lipids, amino acids. Mode of action – coenzymes or parts of coenzymes that are necessary for the proper activity of enzymes, fig 7.9

Without the coenzyme, compounds A and B don’t respond to the enzyme. Active site Enzyme With the coenzyme in place, compounds A and B are attracted to the active site on the enzyme, and they react. B Vitamin A Coenzyme Enzyme The reaction is completed with the formation of a new product. In this case, the product is AB. A B FIGURE 7-9: COENZYME ACTION. Enzyme The product AB is released. A B New product Enzyme Fig. 7-9a, p. 233

Brain and other tissues metabolize carbohydrates. Muscles and other tissues metabolize protein. Bone tissues make new blood cells. FIGURE 7-10: SOME ROLES OF THE B VITAMINS IN METABOLISM: EXAMPLES. This figure does not attempt to teach intricate biochemical pathways or names of B vitamin–containing enzymes. Its sole purpose is to show a few of the many tissue functions that depend on B vitamin–containing enzymes. 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. Many other relationships are also critical to metabolism. Liver and other tissues metabolize fat. Digestive tract lining replaces its cells. Fig. 7-10, p. 234

Water Soluble Vitamins Thiamin and Riboflavin Roles – energy metabolism in cells, part of nerve cell membranes. Deficiencies Beri beri, edema &/or muscle weakness Alcohol abuse – Wernicke-Korsakoff syndrome DRI thiamin:1.1(women) – 1.2(men) mg/day; riboflavin 1.1(women) – 1.3(men) mg/day Sources: All food groups except fats and oils

Snapshot 7-6, p, 236

Snapshot 7-7, p, 237

Water Soluble Vitamins Niacin – can be produced from the amino acid tryptophan. Roles: energy metabolism Deficiencies: Pellagra – dermatitis, diarrhea, dementia, death Toxicities: prevents blood clotting, causes liver damage, enhances action of Coumadin

Water Soluble Vitamins Niacin DRI 14(women) -16(men) mg/day Meats Some vegetables and grains

Snapshot 7-8, p, 238

Water Soluble Vitamins Folate Role: required for synthesis of DNA Deficiencies (drug interactions, smoking) Anemia Decreased immunity Decreased digestive and cardiovascular function Colon and cervical cancers *Neural tube defects, & other birth defects

Water Soluble Vitamins Folate Toxicities (>1000 mg/day): rare, interferes with anticancer drugs. DRI 400 milligrams/day Sources, snapshot 7.8

Snapshot 7-9, p, 240

Water Soluble Vitamins Vitamin B12 (requires intrinsic factor for absorption) Roles: works with folate, part of insulating sheath around nerves. Deficiencies: Pernicious anemia Paralysis Nerve damage in fetus

Water Soluble Vitamins Vitamin B12 DRI 2.3 micrograms/day Sources, see snapshot 7.9 Meat and dairy

Snapshot 7-10, p, 242

Water Soluble Vitamins Vitamin B6 Roles: Conversion of amino acids to other amino acids Ex.: Tryptophan to niacin Synthesis of hemoglobin and neurotransmitters Release of glucose from glycogen Immune function Promotes steroid hormone activity Development of nervous system

Water Soluble Vitamins Vitamin B6 Deficiencies Anemia Dermatitis Muscle weakness Behavioral problems Heart disease Toxicities (>100 mg/day) – muscle weakness, nerve damage

Water Soluble Vitamins Vitamin B6 DRI 1.3 milligrams/day Sources, see snapshot 7.10 Meat and dairy Vegetables and fruits

Snapshot 7-11, p, 243

Water Soluble Vitamins Biotin and Pantothenic acid Roles: Metabolism of carbohydrates, fats and proteins Synthesis of lipids, neurotransmitters, steroid hormones, hemoglobin.

Water Soluble Vitamins Vitamin C, ascorbic acid – history of controversy Roles: Connective tissue development, collagen Antioxidant Promotes iron absorption, immunity Protects vitamin E

Water Soluble Vitamins Vitamin C Deficiency – Scurvy (skin and mucous membrane damage), anemia. Toxicity (> 2grams/day) – pro-oxidant, activates oxidizing agents. DRI – 75(w) – (90(m) milligrams/day. Increased for smokers. Sources, see snapshot 7.11 Notes: can interfere with diagnostic tests for diabetes, and blood clotting Prevents colds

Snapshot 7-5, p, 232