Fat Soluble Vitamins Module 5 1 Vitamins An

Fat Soluble Vitamins Module 5. 1

Vitamins § An organic* substance-coenzyme and/or regulator of metabolic processes § Do not supply calories (energy) § Vitamins are classified by their biological and chemical activity, not their structure-made of single units not long chains § Vitamins must be absorbed by the body in order to perform their functions. § Approximately 40– 90% of vitamins are absorbed in the small intestine. § Some vitamins are absorbed in inactive provitamin or vitamin precursor forms that must be converted into active forms by the body § Two classes: water soluble; fat soluble § Water soluble not stored in body § 8 B vitamins, Vitamin C § Fat soluble stored in the liver and fat tissue § Vitamin A, D, E, K * organic – contains carbon

Comparison of Vitamins in the Body • Fat-soluble vitamins require fat in the diet to be absorbed. § Micelles transport to intestinal wall for absorption § Escorted by chylomicrons via lymph into blood to the liver § Stored in the liver and body fat § absorbed into lymph, many require protein carriers, not readily excreted, § intake deficiency signs and symptoms occur more slowly § toxicity is possible even when intake is normalized. • Water-soluble vitamins may require transport molecules or specific molecules in the GI tract. • absorbed into blood stream directly • circulate, travel, and stored in water • Compartments excrete in urine, without intake • deficiency signs and symptoms occur more quickly • toxicity is possible though shorter lived when intake is normalized.

DIAGNOSING Nutritional Deficiency or Toxicity 1. Dietary records: Demonstrate low/high intake. Medical records can confirm a metabolic or physiological problem that creates an altered need. – Toxicity often found with history of excessive intake of supplements 2. Clinical deficiency or toxicity symptoms: Observable deficiency in actual patients; compatible with low/high dietary intake or altered need. Deficiency attributed to lack of proper nourishment seen in poverty situations, young children and frequent pregnancies. – Toxicity-intake of single supplements such as Vitamin C, E 3. Biochemical tests: Such as blood levels, tissue levels & urine levels demonstrate low/high body levels of the nutrient. 4. Nutrient supplementation: Serves as biological evidence by correcting the deficiency signs & symptoms. For toxicity, removal of the excess.

Fat-Soluble - Vitamin A Functions: vision, maintenance of healthy epithelial tissue (skin and cells lining cavities), sperm production, fetal development, immune response, hearing, taste, and growth • Two types – Retinoids –preformed / active form- animal form – Carotenoids –precursor- plant form • RETINOIDS - preformed or active form 1. Retinol – active form of vitamin A 2. Retinal – vision- combines with opsin to form pigment rhodopsin 3. Retinoic acid- cellular growth and maintenance; skin: wrinkles (Retin-A), acne • Conversion reactions: Retinol ↔ Retinal → Retinoic Acid • The amount of vitamin A present in foods is expressed as retinol activity equivalents (RAE) - a measure of the amount of retinol the body will derive from food. – RAE Equivalents: Based on active form retinol 1 RAE = 1 µg retinol 1 RAE = 2 µg supplemental beta-carotene 1 RAE = 12 µg dietary beta-carotene

Vitamin A Fat-Soluble Vitamins 2. Carotenoids – Vitamin A precursor • Intestinal cells convert carotenoids into vitamin A. • Found in plant products • Beta-carotene: an orange pigment found in plants that is converted into vitamin A inside the body. Beta-carotene is also an antioxidant • Sources: apricots, cantaloupe, carrots http: //www. superlutein. net/export/sites/superlutein/en/gl/images/faq/image-01. jpg

Vitamin A Functions 1. 2. 3. 4. 5. Vision, hearing, taste Growth; Embryonic development Gene expression Immune function Maintenance of healthy epithelial tissue (skin, internal & external surface linings) 6. Reproduction (sperm and fetal development) 7. Antioxidant properties

Fat-Soluble Vitamins - Vitamin A Up to a year’s supply can be stored; 90% in the liver. § Transported through the blood by retinal binding protein. § Vitamin A toxicity can lead to consequences. § Hypercarotnemia – orange hue to skin – result of excessive intake – often seen in vegetarians • Vitamin A deficiency result of insufficient intake of vitamin A, fat, protein or zinc § Deficiency occurs after reserves depleted. § Consequences include night blindness and reduced resistance to infection, skin conditions, poor bone growth § Xerophthalmia - dry eyes- condition where the eye fails to produce tears. Cornea thickens- interferes with light entering the eye-results in irreversible blindness § Medications made from vitamin A, such as Retin A or Accutane, can cause serious side effects – birth defects, increase in LDL cholesterol

Vitamin A Deficiency vs Toxicity Deficiency Adequacy Toxicity (<66% of DRI) Approx. <500 µg RE/day DRI: 700 -900 µg RE/day (>UL) >3, 000 µg RE/day Hypovitaminosis A • Bone & tooth: Impaired growth • Central Nervous System: • Night blindness, complete blindness (Xerophthalmia) • GI System: Diarrhea • Immunity: Depressed immunity, more • infections • Skin: Hyperkeratosis (thickened skin) RDI: 5, 000 IU Normal vision, gene expression, reproduction, embryonic development, epithelial cell maintenance, growth, and immune function 25 mg betacarotene (provitamin A is safe to take daily if you are not a smoker or drinker). • Bone & tooth: Decreased bone mineral density • Central Nervous System: Headache, vertigo • GI System: Nausea and vomiting, liver abnormalities • Neuro-Muscular: Incoordination • Skin: orange color with excess beta-carotene • Other: Retinoid embryopathy Adult deficient, adequate, toxic values

Vitamin A in Foods Retinol: (animal) • Fortified milk, cheese, butter, margarine • Eggs • Liver Adult DRI: 700 -900 µg RE/day Beta-Carotene: (Plant) • dark green leafy vegetables • broccoli, deep orange fruits, & vegetables

Fat-Soluble Vitamins Vitamin D • Both a vitamin and a hormone • Functions in bone production and maintenance osteomalacia – Increases bone mineralization • Body synthesizes with sunlight (5 -15 mins) • Deficiency diseases ü In children, rickets ü In adults, osteomalacia • Assists in the absorption of dietary calcium § Increases intestinal absorption of calcium (Absorption from food in intestines) § Re-absorption of calcium in kidneys • Regulates and balances calcium and phosphorus availability in blood » Increase phosphorus excretion rickets • Reduces cell division (Antiproliferative) – of cancer cell formation and promotes cellular differentiation of new cells (Prodifferentiation)

Vitamin D Synthesis 1. Vitamin D 3 (cholecalciferol) synthesized by the cholesterol in skin’s exposure to sun. 2. Cholecalciferol converted to calcidiol in liver 3. Calcidiol converted to calcitriol in kidneys to active form of Vitamin D

an s i f re The emic o d epi min D vita iency ic def Vitamin D Deficiency vs Toxicity Deficiency Adequacy Toxicity (<66% of DRI) Approx. <3 µg/day DRI: 15 µg/day (>UL) >50 µg/day RDI: 400 IU = 6. 5 µg • Rickets (children) Normal calcium • Osteomalacia (adults) and phosphorus • Bone & tooth: poor growth, bowed legs, soft bones, pigeon balance and cell chest, knocked knees, and metabolism malformed teeth in children. Porous bones in adults. • Cardio-Vascular: Needs are based increased circulating levels upon an inadequate (PTH) and (Alk. P) and exposure to decreased circulating levels of sunlight. serum phosphorus Sunlight not • GI System: Decreased calcium implicated in toxicity. absorption • Hypervitaminosis D characterized by high levels of 25(OH)D from supplementation • Cardio-Vascular: High blood calcium • Central Nervous System: Weakness • GI System: Nausea, vomiting, anorexia • Other: Kidney stones, increased thirst, urination, and urinary calcium Adult deficient, adequate, toxic values

Vitamin D in Foods Food sources: • Fortified products like milk, margarine, & some cereals • Eggs & fatty fish • Self-synthesis with unprotected peak sunlight exposure Adult DRI: 15 µg/day

Fat-Soluble Vitamins Vitamin E-Tocopherol • Vitamin E chemistry • A family of alpha, beta, gamma, delta tocopherols & tocotrienols. • Alpha-tocopherol is believed to be the most active form. • Known as a vitamin in search of a disease • Needed for growth and fertility – Vitamin E deficiency in newborns might result in hemolytic anemia. • Antioxidant • Absorbed from small intestine and transported by chylomicrons • Sources: vegetable oils, nuts, seeds, margarine, soybean • Deficiencies of the nutrient are rare. – risk of deficiency: • Premature infants not receiving vitamin E from mothers. • Fat malabsorption diseases. • certain blood disorders.

Vitamin E Functions And at the molecular level

Vitamin E in Foods Food sources: • Nuts • Seeds • Plant oils • Wheat germ • Fortified cereals • Vegetables Adult DRI: 15 mg/day

Vitamin E Deficiency vs Toxicity Deficiency (<66% of DRI) Approx. <10 mg/day • Premature infants: hemolytic anemia • Adults: not well characterized Adequacy DRI: 15 mg/day RDI: 30 IU Toxicity (>UL) >1, 000 mg/day Normal cell • Relatively nontoxic membrane integrity, • Toxicity with reduced oxidative supplements stress, and molecular • Interferes with functioning vitamin K’s role in blood clotting, augmentation of anti -blood clotting medication and increases hemolysis Adult deficient, adequate, toxic values

Fat-Soluble Vitamins Vitamin K Found in several forms, including phylloquinon and menaquinone. • BLOOD-CLOTTING system of the body. • Works with vitamin D to regulate calcium levels in the blood. Calcium required in blood clotting mechanisms • Deficiencies rare-obtained both in the diet and via the intestinal bacteria. Antibiotics can decrease flora and production of Vitamin K – Newborn babies are the one group that is commonly susceptible to a vitamin K deficiency. • A baby’s digestive tract is free of bacteria until birth.

Vitamin K Deficiency vs Toxicity Deficiency Adequacy Toxicity (<66% of DRI) Approx. <60 µg/day DRI: 90 -120 µg /day RDI: 90 µg (>UL) Not Determined • Cardio. Vascular: • Increases clotting time, hemorrhaging with cut or injury Normal blood Poorly described in adults clotting & bone • GI System: High levels from supplemented metabolism menadione causes jaundice and liver damage in infants • Cardio-Vascular: Interference with antiblood clotting medication Adult deficient, adequate, toxic values

Vitamin K in Foods Food Sources: • Green leafy & cruciferous vegetables • Soybeans • Some plant oils Adult DRI: 90 -120 µg/day