Fat Soluble Vitamins

By Jennifer Turley and Joan Thompson

© 2013 Cengage

Presentation Overview

• Comparison of vitamins in the body.• Diagnosing deficiency and toxicity.• The fat soluble vitamins, A, D, E, K.• Notable health implications.

Chemical Forms. Intake Need. Functions. Deficiency. Toxicity. Food Sources.

Vitamin A Vitamin D

Vitamin E Vitamin K

Water Soluble: absorbed into blood stream directly, circulate, travel, and stored in watercompartments, excrete in urine, without intake deficiency signs and symptoms occur more quickly, toxicity is possible though shorter lived when intake is normalized.

Fat Soluble: absorbed into lymph, many require protein carriers, associate with fat, not readily excreted, without intake deficiency signs and symptoms occur more slowly, toxicity is possible and longer lived even when intake is normalized.

Thiamin

Riboflavin

Niacin

B6

B12

Folate

Vitamin C

Pantothenic Acid

Biotin

Choline

Vitamin A Vitamin DComparison of

Vitamins in the BodyVitamin E

Vitamin K

1. Dietary records: Demonstrate low/high intake and/or confirm a metabolic or physiological problem that creates an altered need.

2. Clinical deficiency or toxicity symptoms: Are compatible with low/high dietary intake or altered need.

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.

Diagnosing Nutritional Deficiencyor Toxicity

The Fat Soluble Vitamins

Vitamin A Chemistry

• A family of compounds including: – Retinol, Retinal, Retinoic acid– Pro-Vitamin A carotenoids like beta-carotene

Retinyl Esters(animal foods)

Beta-Carotene(plant foods)

Retinal(vision)

Retinol(reproduction)

Retinoic Acid(Growth Regulator)

Vitamin A Functions• Vision• Internal & external

surface linings (epithelial cells)

• Growth• Reproduction• Embryonic development• Gene expression• Immune function• Provitamin A forms

have antioxidant properties

Vitamin A Deficiency vs Toxicity

Deficiency(<66% of DRI)

Approx. <500 µg RE/day

Adequacy DRI: 700-900 µg RE/day

RDI: 5,000 IU

Toxicity (>UL)

>3,000 µg RE/day

Hypovitaminosis A Bone & tooth: Impaired growthCentral Nervous System: Night blindness, complete blindness (Xerophthalmia)GI System: DiarrheaImmunity: Depressed immunity, moreinfectionsSkin: Hyperkeratosis (thickened skin)

Normal vision, gene expression, reproduction, embryonic development,

epithelial cell maintenance, growth, and

immune function

Bone & tooth: Decreased bone mineral densityCentral Nervous System: Headache, vertigoGI System: Nausea and vomiting, liver abnormalitiesNeuro-Muscular: IncoordinationSkin: orange color with excess beta-caroteneOther: Retinoid embryopathy

Adult deficient, adequate, toxic values

25 mg beta-carotene (pro-

vitamin A is safe to take daily if you

are not a smoker or drinker).

Vitamin A: Food Sources

• Retinol: (animal)• Fortified milk, cheese, butter, margarine • Eggs• Liver • Beta-Carotene: (Plant)• dark green leafy vegetables• broccoli, deep orange fruits, & vegetables

Vitamin A in Foods

Adult DRI: 700-900 µg RE/day

Vitamin D ChemistrySynthesis & Functions

REGULATES Ca-P Balance

• Increases bone mineralization

• Increases intestinal absorption of calcium

• Increase phosphorus excretion

AntiproliferativeProdifferentiation

Vitamin D Deficiency vs Toxicity

Deficiency(<66% of DRI)

Approx. <3 µg/day

Adequacy DRI: 15 µg/day

RDI: 400 IU = 6.5 µg

Toxicity (>UL)

>50 µg/day

Rickets (children)Osteomalacia (adults)Bone & tooth: poor growth, bowed legs, soft bones, pigeon chest, knocked knees, and malformed teeth in children. Porous bones in adults.Cardio-Vascular:increased circulating levels (PTH) and (AlkP) and decreased circulating levels of serum phosphorus GI System: Decreased calcium absorption

Normal calcium and

phosphorus balance and

cell metabolism

Hypervitaminosis D characterized by high levels of 25(OH)D from supplementationCardio-Vascular: High blood calciumCentral Nervous System: WeaknessGI System: Nausea, vomiting, anorexiaOther: Kidney stones, increased thirst, urination, and urinary calcium

Adult deficient, adequate, toxic values

Needs are based upon an inadequate

exposure to sunlight.

Sunlight not implicated in

toxicity.

There is an

epidemic of vita

min

D deficiency

Vitamin D: Sources

• Fortified products like milk, margarine, & some cereals

• Eggs & fatty fish• Self-synthesis with unprotected

peak sunlight exposure

Vitamin D in Foods

Adult DRI: 15 µg/day

Vitamin E Chemistry

• A family of alpha, beta, gamma, delta tocopherols & tocotrienols.

• Alpha-tocopherol is believed to be the most active form.

Vitamin E Functions

And at the molecular level

And at the molecular level

Vitamin E Deficiency vs Toxicity

Deficiency(<66% of DRI)

Approx. <10 mg/day

Adequacy DRI: 15 mg/day

RDI: 30 IU

Toxicity (>UL)

>1,000 mg/day

Premature infants: hemolytic anemiaAdults: not well characterized

Normal cell membrane

integrity, reduced oxidative stress, and molecular

functioning

Relatively nontoxicToxicity with supplements

Interferes with vitamin K’s role in

blood clotting, augmentation of

anti-blood clotting medication and

increases hemolysis

Adult deficient, adequate, toxic values

Vitamin E: Food Sources• Nuts• Seeds• Plant oils• Wheat germ• Fortified cereals• Vegetables

Vitamin E in Foods

Adult DRI: 15 mg/day

Vitamin K Chemistry• Phylloquinone (K1) from plant sources &

naphthaquinones (K2, multiple forms) from animal sources & gut bacteria.

Vitamin K Deficiency vs Toxicity

Deficiency(<66% of DRI)

Approx. <60 µg/day

Adequacy DRI: 90-120 µg /day

RDI: 90 µg

Toxicity (>UL)

Not Determined

Cardio-Vascular:Increases clotting time, hemorrhaging with cut or injury

Normal blood clotting & bone

metabolism

Poorly described in adults

GI System: High levels from supplemented menadione causes jaundice and liver damage in infantsCardio-Vascular:Interference with anti-blood clotting medication

Adult deficient, adequate, toxic values

Vitamin K: Sources• Green leafy & cruciferous

vegetables• Soybeans• Some plant oils

Vitamin K is made by bacteria in the gastrointestinal tract

Vitamin K in Foods

Adult DRI: 90-120 µg/day

Summary

• Diagnosing & confirming a nutrient deficiency or toxicity requires a diet analysis, clinical evaluation, biochemical analysis, & evaluating the response to corrected intake levels.

• Toxicities and deficiencies take longer to develop for fat soluble vitamins as compared to water soluble vitamins.

• The fat soluble vitamins are grouped by their solubility in oil.• The fat soluble vitamins have specific chemical forms &

functions in the body.• DRIs exist for essential fat soluble vitamins: A, D, E, & K.• Deficiency & toxicity signs & symptoms are unique for each of

these nutrients as are their food sources.

References for this presentation are the same as those for this topic found in module 5 of the textbook