Chapter 11 Fat Soluble Vitamins: ADEK

Chapter 11

Fat Soluble Vitamins:ADEK

Chapter 11 - FSVCharacteristics of fat-soluble vitamins• Do not dissolve in water, but dissolve in fat or

organic solvents.• Dietary fat soluble vitamins need bile for

absorption.• The fat-soluble vitamins include vitamins A, D,E

and K• Found in the fats and oils of foods.• Stored in the liver and fat tissue until needed• not readily excreted from the body. • Risk of toxicity.

Storage of vitamins in the body

• Vitamins A, D and E: – These three fat-soluble vitamins can

accumulate in the liver and fat tissue of the body and are not readily excreted. Long-term intakes more than the RDA can be toxic, particularly vitamins A and D.

• Vitamin K:– The other fat-soluble vitamin, vitamin K, is

readily excreted from the body.

Absorption & transport

• The fat-soluble vitamins, like lipids are absorbed with dietary fat. – Bile aids in the absorption of fat-soluble

vitamins. – The GI must function adequately for efficient

uptake of fat-soluble vitamins.

• Under normal conditions, healthy individuals will absorb 40-90% of fat-soluble vitamins.

Absorption & TransportFat malabsorption interfere with the

absorption of FSV.

• Unabsorbed fat is excreted as feces.

• The following conditions adversely affect the uptake of fat-soluble vitamins:

– Cystic fibrosis

– Crohn’s disease

– Celiac disease

– Certain medications

Family of compounds called Retinoids:• Retinol – supports reproductive functions

– Found in animal foods and nutrient supplements. – Can converted to retinoic acid and retinal in the body.

• Retinal – Aid in vision• Retinoic acid – regulates growth• ~90% of retinoids are absorbed• These are preformed Vitamin A – form that

the body readily uses. Found only in animal sources

Vitamin A

Provitamin A = carotenoids• Found in plant sources• Not biologically available until they are

changed into one of the retinoids in the body

• There are over 600 different carotenoids only 3 can be converted to vitamin A– Beta carotene (most common form)– Alpha carotene– Beta- cryptoxanthin

• Accounts for 25 – 35 percent of dietary vitamin A consumed in the US

Functions of Vit A

• Essential for healthy eyes• Promotes cell differentiation

– Determines what cell becomes in your body– Supports reproductive system, development of

limbs, heart eyes and ears

• Promotes bone and teeth growth• Play a role in immunity and preventing

infections by creating white blood cells• Carotenoids, which act as antioxidants,

decrease the damaging effects of free radicals.

Sources of Vitamin ASources • Preformed Vit A

– Organ meats (liver), milk, cereals, cheese and eggs are the most popular sources of

• Provitamin A (carotenoids)– Fruits: peaches, apricots, cantaloupes, mangoes,

papaya– Vegetables: tomatoes, carrots, winter squash, sweet

potatoes, broccoli, romaine lettuce, collard greens and spinach.

– Adding as little as 1 tablespoon of vegetable oil to your diet can increase absorption of carotenoids by as much as 25%

Vitamin ARDA – can be measured in micrograms of retinoic

activity equivalents (RAE) or in international units (IU). 1 RAE = 3.3 IU

• 900 microgram for men• 700 microgram for women• Upper limit 3,000 microgram/dayDeficiency• Night blindness – difficulty seeing at dusk, can’t adjust

from day light to dark• Vitamin A deficiency is the main cause of non-accidental

blindness (Xerophthalmia)• Many die after blindness as a result of infection.

– The eye becomes prone to infections when the conjunctiva is damaged.

– Infections can spread systemically throughout the body.

Toxicity • Hypervitaminosis A - is a condition that results

from excessive intake of vitamin A from supplements

• Cause defective physical development during early development of the fetus resulting in birth defects– Even 3X RDA vitamin A is considered risky during

pregnancy.

• Accutane is associated with congenital malformations result involving the head and brain.

• FDA has recommended that women of childbearing years limit their vitamin A intake to 100% RDA

Toxicity

• High consumption of vitamin A has been linked to osteoporosis and increased risk of fractures

• Provitamin A carotenoids in foods are not toxic

• Extra carotenoids are stored in the liver and in the fat under the skin, causing carotenodermia

Fig. 11-7, p. 375

Vitamin D/calceferol

• Also called the “sunshine vitamin” because it is made with the help of ultraviolet (UV) rays from sunlight

• Vitamin D enters your body in an inactive form

• The kidneys convert dietary vitamin D into the active form

• Precursor = body’s cholesterol

Vitamin D/ calceferol

• Functions of Vit D– Helps bone health by regulating calcium and

phosphorus concentration in the blood– When blood concentration of calcium is low,

vitamin D and parathyroid hormone signals the kidney to decrease excretion of calcium and phosphorous

• Sources of vit D– Fortified milk, cereals, yogurt, fatty fish

Vitamin D

Adequate Intake:• 5 micrograms/day for 19-50 yr• 10 micrograms/day for 51-70 yr• 15 micrograms/day for >70 yr• Upper level: 50 micrograms/day

Vitamin D

Deficiency• Rickets in children (soft bones)

– poor bone mineralization– Bowed legs– Unable to hold up their own weight when

standing up– Recently researchers have found a rise in

rickets among children, • linked to increase consumption of soft drinks• Limited outdoor activities• Fear of skin cancer• Air pollution reduces ultraviolet rays of the sun by

as much as 60%

Vitamin D

Osteomalacia - adult form of rickets• Occurs in women with decreased calcium

and phosphorus intake• Causes bone weakness and pain• Can lead to osteoporosis

Vitamin D Toxicity

Hypervitaminosis D – associated with over-consumption of supplements

• Increased calcium withdrawal in bones and intestines

• Increased calcium and phosphorous concentrations in the blood

(hypercalcemia)• Increase calcium deposits in kidneys,

lungs, blood vessels and heart

Vitamin E

• Vitamin E is an effective antioxidant– Prevent oxidation of lipids, vit A and LDL to

prevent build-up in the arteries– Neutralize free radicals before they damage cell

membranes– Prevents blood clotting in the blood by acting as

anticoagulant

• There are 8 different forms, only one is active in the body (alpha- tocopherol)

• The synthetic is only half as active as the natural

Vitamin E

Sources• Polyunsaturated plant oils (vegetable oils)• Nuts and seeds • Leafy green vegetables• Fortified cereals

RDA:Adults need 15 milligrams/dayUpper limit is 1,000 milligrams

Vitamin EDeficiency• Erythrocyte hemolysis in premature infants

(red blood cell destruction causing anemia)

Toxicity from synthetic form or fortified foods• increase risk of hemorrhage• A deficiency of vitamin K can increase the

anticoagulant effect

Vitamin KThere are two forms of vitamin K:• Menaquinone – synthesized by the intestinal

tract• Phylloquinone – found in green plants

Functions• Essential for blood clotting• Vitamin K plays a role synthesizing clotting

factors• Without vit k a simple cut on the finger would

cause uncontrollable bleeding • Synthesis of bone protein (osteocalcin) that

regulates blood calcium.

Vitamin K• Inadequate amount of vitamin K may

contribute to osteoporosis, associated with increased risk of hip fractures

Sources• Intestinal bacteria can make vitamin K but

not enough to meet all of the body’s needs• Leafy green vegetables• Cabbage family vegetables• Vegetable oils and margarine

Vitamin K

Deficiency• Newborn infants receive a single dose of vitamin

K at birth because of a sterile intestinal tract to prevent hemorrhagic disease

• Rare in healthy individuals

Toxicity• No known adverse effect from consuming too

much vitamin K from food or supplement• Interferes with anticlotting medication

(coumadin)

Recommendation for Vitamin K

Adequate Intake (based on amount that is consumed on average)

Infants: 2 – 2.5 microgram

Children: 30 – 55 microgram

Men: 60 – 120 microgram

Women: 60 – 90 microgram

Homework/extra credit

5 points

Complete the vitamin/mineral evaluation form posted on the course website