vitamins. definition and classification non-caloric organic nutrients needed in very small amounts...
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VITAMINS
Definition and Classification
Non-caloric organic nutrientsNeeded in very small amountsFacilitators – help body processes
proceed; digestion, absorption, metabolism, growth etc.
Some appear in food as precursors or provitamins
Definition and Classification
2 classesFat soluble:
Water soluble:
Definition and Classification
Fat soluble vitaminsFound 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 vitaminsFound in vegetables, fruit and grains, meat.Absorbed directly into the blood streamNot 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 ADeficiencies cause:
Night blindness, xerophthalmia (keratin deposits in cornea), muscular degeneration.
Skin and mucous membrane dryness and infection, keratin deposits.
AnemiaDevelopmental defects – bones, teeth, immune
system, vision
Fat Soluble Vitamins
Vitamin AToxicities (RetinA/Accutaine, single large
doses of supplements, eating excessive amounts of liver) cause:
Fragile RBCs, hemorrhageBone pain, fracturesAbdominal pain and diarrheaBlurred visionDry skin, hair lossLiver enlargement
Fat Soluble Vitamins
Vitamin ADRI: 700(women)-900(men)
micrograms/day, UL 3000 micrograms/day
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 DDeficiencies: 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
Fig. 7-5b, p. 222
Beaded ribs – Characteristic of rickets
Fat Soluble Vitamins
Vitamin DDRI – 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), heartNecessary for normal nerve development
Fat Soluble Vitamins
Vitamin EDeficiencies (decreased absorption of fats-
liver disease, low fat diets)Premature babies – fragile RBCs (hemolysis)Loss of muscle coordination, vision, immune
functionsToxicities (more than 1000 milligrams/day)
Increases the effects of anticoagulants (Coumadin, Warfarin)
Fat Soluble Vitamins
Vitamin EDRI 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 KDRI: 90(women) – 120(men)
micrograms/daySources, 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
Fig. 7-9a, p. 233
Compounds
Active site
Enzyme
Without the coenzyme, compounds A and B don’t respond to the enzyme.
AB
With the coenzyme in place, compounds A and B are attracted to the active site on the enzyme, and they react.
Enzyme
AB Vitamin
Coenzyme
The reaction is completed with the formation of a new product. In this case, the product is AB. Enzyme
Enzyme
A B
The product AB is released. New productA B
Fig. 7-10, p. 234
Muscles and other tissues metabolize protein.
Brain and other tissues metabolize carbohydrates.
Bone tissues make new blood cells.
Liver and other tissues metabolize fat.
Digestive tract lining replaces its cells.
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 metabolismDeficiencies: Pellagra – dermatitis,
diarrhea, dementia, deathToxicities: prevents blood clotting, causes
liver damage, enhances action of Coumadin
Water Soluble Vitamins
NiacinDRI 14(women) -16(men) mg/day
MeatsSome vegetables and grains
Snapshot 7-8, p, 238
Water Soluble Vitamins
FolateRole: required for synthesis of DNA Deficiencies (drug interactions, smoking)
AnemiaDecreased immunityDecreased digestive and cardiovascular functionColon and cervical cancers*Neural tube defects, & other birth defects
Water Soluble Vitamins
FolateToxicities (>1000 mg/day): rare, interferes
with anticancer drugs.DRI 400 milligrams/daySources, 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 anemiaParalysisNerve damage in fetus
Water Soluble Vitamins
Vitamin B12
DRI 2.3 micrograms/daySources, 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 neurotransmittersRelease of glucose from glycogen Immune functionPromotes steroid hormone activityDevelopment of nervous system
Water Soluble Vitamins
Vitamin B6Deficiencies
AnemiaDermatitisMuscle weaknessBehavioral problemsHeart disease
Toxicities (>100 mg/day) – muscle weakness, nerve damage
Water Soluble Vitamins
Vitamin B6DRI 1.3 milligrams/daySources, see snapshot 7.10
Meat and dairyVegetables and fruits
Snapshot 7-11, p, 243
Water Soluble Vitamins
Biotin and Pantothenic acidRoles:
Metabolism of carbohydrates, fats and proteinsSynthesis of lipids, neurotransmitters, steroid
hormones, hemoglobin.
Water Soluble Vitamins
Vitamin C, ascorbic acid – history of controversyRoles:
Connective tissue development, collagenAntioxidantPromotes iron absorption, immunityProtects 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