fat soluble vitamins water soluble vitamins the vitamins
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Objectives
Vitamins are micronutrients Very small amounts are needed by the body (>1 gm) Very small amounts are contained in foods.
Vitamins are essential. The roles they play in the body are very important. Most vitamins are obtained from the foods we eat. Some are made by bacteria in the intestine One is made in the skin
There is no perfect food that contains all the vitamins in the right amount.
Characteristics of Vitamins
Objectives
Vitamins are non-energy producing They do not contain kcalories. They are involved in extracting energy
from the macronutrients. Some vitamins in foods are
precursors. Vitamins are classified according
to how soluble they are in fat or water.
Characteristics of Vitamins
Objectives
After reading Chapter 6, completing a concept map and class discussion, you will be able to:
Identify fat soluble vitamins Distinguish fat soluble vs water soluble Identify food sources for Vitamins A,D,E,K Identify toxicity levels for Vitamins A,D,E,K Describe one major role for Vitamins A,D,E,K
Objectives
Fat Soluble Vitamins: Characteristics Essential Organic Structure Non-energy Producing Micronutrients Stability Bioavailability Toxicity
Toxicity Toxicity is rare but it is a possibility. Toxicity is very rarely associated with
food. Toxicity results from overuse of
supplements.
Other names Preformed Vitamin A – retinyl esters
Retinol, Retinal, Retinoic acid Sources: animal foods, fortified foods,
pharmaceutical supplements Provitamin A - Precursors=carotenoids
Beta-carotene and other carotenoids Sources: plant foods
Vitamin A
2001 RDA Men: 900 g RAE/day Women: 700 g RAE/day RAE=Retinol Activity Equivalents
1 microgram of retinol 12 micrograms of beta-carotene 24 micrograms of other precursor carotenoid
Upper level for adults: 3000 g/day
Vitamin A
Chief functions in the body Vision Maintenance of cornea, epithelial
cells, mucous membranes, skin Bone and tooth growth Reproduction Immunity Antioxidant effect of beta-carotene
Vitamin A
Night blindness Xerosis (corneal drying) Bitot’s spots Karatomalacia Xerophtalmia Hyperkaratosis Impaired immunity
Vitamin A Deficiency
Toxicity from provitamin A impossible Conversion of carotenoids to retinal highly
regulated by the body Homeostatic mechanisms control tightly
Toxicity from preformed A inevitable Efficient absorption and hepatic storage of A Storage continues until pathologic condition
develops; liver stores ~80% of body reserves
Vitamin A Toxicity
Large % of population in developed nations have intakes of preformed vitamin A higher than the RDA 75% of people may be routinely ingesting
more than RDA Some studies suggest that as little as
twice the RDA intake may contribute to subclinical Vitamin A toxicity
Vitamin A Toxicity
Occurs when adults ingest >100x RDA of preformed Vitamin A for a period of hours or several days.
Occurs when children ingest >20x RDA of preformed Vitamin A for same period.
Less of a problem than chronic toxicity
Acute Toxicity
Acute toxicity symptoms Blurred vision Nausea, vomiting, vertigo Increase of pressure inside skull,
mimicking brain tumor Headaches
Acute Toxicity
Occurs when adults ingest >25,000 IU preformed Vitamin A for >6 years >100,000 IU preformed A for >6 months
Wide individual variabilty Children particularly sensitive to daily
intakes of 1500 IU/kg body weight. Elderly at significantly greater risk
Chronic Toxicity
Chronic toxicity symptoms Increased activity of osteoclasts
causing reduced bone density Liver abnormalities Birth defects
Chronic Toxicity
Vitamin A & Macular Degeneration
Studies in the elderly suggest that the use of large doses of certain vitamins and minerals are beneficial in the prevention of macular degeneration
Some evidence exists that improvement in existing damage may be seen
Vitamin/
Mineral
Amount % DV
A 14,320 IU 286
C 235 mg 371
E 200 IU 667
Zinc 348 mg 232
Copper 0.8 mg 40
Vitamin A & Macular Degeneration
Vitamin A directs the process of borrowing and redepositing calcium in the bone
Too much preformed Vitamin A (retinol) can promote fractures.
Use Vitamin A in form of beta-carotene, a pre-curser form which does not increase fractures
Vitamin A & Macular Degeneration
Beta-carotene Dark leafy green
vegetables, spinach, broccoli
Deep orange veggies Carrots, pumpkin,
squash, sweet potato Deep orange fruits
Apricots, cantaloupe
Vitamin A Sources
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Other names Calciferol 1,25-dihyroxy vitamin D (calcitriol) Animal version: vitamin D3 or
cholecalciferol Plant version: vitamin D2 or ergocalciferol Precursor is the body’s own cholesterol
Vitamin D
1997 adequate intake (AI) 19-50 years: 5 g/day 51-70 years: 10 g/day more than 70 years: 15 g/day
Upper level for adults: 50 g/day
Vitamin D
Chief functions in the body Mineralization of bones
raises blood calcium and phosphorus by increasing absorption from digestive tract
withdrawing calcium from bones stimulating retention by kidneys)
Vitamin D
Calcium and phosphorous absorption Without D only 10-15% dietary calcium
absorbed With D absorption increased to 30-40% Without D about 60% phosphorous
absorbed With D absorption increased to ~80%
Vitamin D
Recent research indicates Vitamin D has a role in the prevention of Heart disease Type-1 Diabetes Multiple Sclerosis Rheumatoid Arthritis Crohn’s Disease Certain Cancers
Vitamin D
Nonskeletal functions of Vitamin D Brain, prostate, breast, colon tissues and
immune cells have Vitamin D receptors and respond to 1,25-dihydroxyvitamin D (the active form of D)
1,25-dihydroxyvitamin D controls more than 200 genes
Potent immunomodulator
Vitamin D
Deficiency Rickets
Inadequate calcification Misshapen, deformed
Lax muscles with spasm Osteomalacia
Loss of calcium Soft, deformed bones Pain, weakness
Vitamin D
Toxicity – Hypervitaminosis D Elevated blood calcium Calcification of soft tissues (blood
vessels, kidneys, heart, lungs, tissues around joints)
Thought to be the most frequently occurring vitamin toxicity but………..
Vitamin D
The Sunshine Vitamin Approximately 90% of
Vitamin D requirement obtained from sun
UV light from sun hits skin, triggers synthesis
Activated in liver and kidneys
Vitamin D
Fortified Milk Margarine Butter Cereal
Veal, Beef Egg yolk Fatty fish (salmon, sardines, herring)
Vitamin D Sources
Other name: alpha-tocopherol 2000 RDA
Adults: 15 mg/day Upper level for adults: 1000
mg/day Easily destroyed by heat and
oxygen
Vitamin E
Chief function in the body Antioxidant
stabilization of cell membranes, regulation of oxidation reactions, protection of polyunsaturated fatty
acids and vitamin A
Vitamin E
Polyunsaturated plant oils Margarine Salad dressing
Leafy green vegetables Wheat germ Whole grains Egg yolks Nuts and seeds
Vitamin E Sources
Other names Phylloquinone Manaquinone Menadione Naphthoquinone
2001 AI Men: 120 g/day Women: 90 g/day
Vitamin K
Family of vitamins Naturally found in primarily two forms
K1 and K2
K3 simpler form; synthetically created
Identified by German scientists Required for normal blood clotting
Named “K” for German word for “clot” No Tolerable Upper Limit
Vitamin K
Bacteria in intestines produce ~75% of Vitamin K absorbed by body daily
Vitamin K not stored in body Vitamin K needs to be supplied
daily Absorption dependent on healthy
liver and gall bladder
Vitamin K
K1 produced by plants we eat K2 produced by bacteria in intestine;
converted from K1
K2 more potent (15x); more active; and wider range of activities Better absorbed; longer biological activity Predominant form found in body tissues Used preferentially by all tissues but liver
Vitamin K
Chief functions in the body Synthesis of blood-clotting proteins
and bone proteins that regulate blood calcium
Vitamin K
Synthesis of bone proteins that regulate blood calcium; prevent bone loss
Integration of calcium into bones Prevent calcium deposition in blood
vessels (vascular calcification) Maintain blood vessel elasticity
Vitamin K: Other Functions
Bisphosponates – osteoporosis drugs K improves utilization of these drugs
Wafarin - anticoagulants As little as 1 mg/day can interfere
with anticoagulant activity of drug
Vitamin K and Medication
Bacterial synthesis in GI tract
Leafy green vegetables
Cruciferous vegetables
Liver Milk
Vitamin K Sources
Vitamin K1 produced by plants and algae Broccoli, kale, chard; plant oils like canola
and soybean Hydrogenated soybean oil has ineffective K
Vitamin K2 produced by bacteria in gut Food Sources: fermented soybean (Natto);
dairy products, egg yolk
Vitamin K Sources
Objectives
After reading Chapter 6, completing a concept map and class discussion, you will be able to:
Identify fat soluble vitamins Distinguish fat soluble vs water soluble Identify food sources for Vitamins A,D,E,K Identify toxicity levels for Vitamins A,D,E,K Describe one major role for Vitamins A,D,E,K
Objectives