fat soluble vitamins

fat soluble vitamins

D, E, K, A

water soluble vitamins

B vitamins and vitamin C

fat soluble

- stored longer periods of time

- larger amounts

- in liver and fat cells

- increased likelihood of adverse effects of toxicity

water soluble

- stored shorter periods of time

- smaller amounts

- decrease likelihood of toxicity

- greater risk of deficiency

water soluble absorption and transportation

- absorbed directly into blood

- transported freely

- storage: circulate freely in water-filled parts of body

- excretion: kidneys detect and remove excess in urine

- toxicity: possible to reach toxic levels when consumed from supplements

- requirements: needed in frequent doses (1-3 days)

fat soluble absorption and transportation

- absorbed first into lymph, then blood

- transport: requires protein carriers

- storage: stored in the cells associated with fat

- excretion: less readily excreted, tends to remain in fat-storage sites

- toxicity: likely to reach toxic levels when consumed from supplements

requirements: needed in periodic doses (weeks or months)

Bioavailability

the degree to which a nutrient is absorbed from foods and used in the body

Fat soluble vitamins are generally __________ bc they require _______ and the formation of a _________ to be absorbed

less bioavailable; bile salts; micelle

Vitamins in plant foods are typically _________ bioavailable than those in animal foods.

less bioavailable; plant fiber trap vitamins

preformed vitamin A

Active form found in animal products.

provitamin A

An inactive form of a vitamin that the body can convert to an active form. An example is beta-carotene.

functions of Vitamin A

vision, immune function, integrity of epithelial cells, cell differentiation, gene regulation, bone metabolism

Dietary and non-dietary sources of Vitamin A

DIETARY

- Preformed (animal): Liver, eggs, fortified milk, cheese

- Provitamin (plant): dark green and deep orange fruits and veggies such as carrots, sweet potatoes, spinach, cantaloupe

vitamin A transport protein

retinol binding protein (RBP)

Vitamin A toxicity (high levels)

- generally from taking supplements

- hypervitaminosis A

- during pregnancy leads to fetal malformations

- osteoporosis

Carotenoids

not toxic; decreases conversion to retinol

carotenodermia

eat too many caroteniods -> orange-tinted skin on palms of hands

Vitamin A Deficiencies

Night blindness; Xerophthalmia; Keratinization

Night blindness

the inability to see in dim light or at night due to a deficiency of vitamin A

xerophthalmia

irreversible blindness from vitamin A deficiency; drying and scarring of the cornea

keratinization

abnormal hardness and drying of epithelial tissues to due vitamin A deficiency.

vitamin D

also called cholecalciferol

synthesis and activation of vitamin D in skin

- 7 dehydrocholesterol converted to previtamin D3 (inactive) when exposed to UV light -> heat from body forms vitamin D3

- liver then forms calcidiol (circulating form) and kidneys forms calcitriol (active form) via hydroxylation

synthesis and activation of vitamin D from diet

- consume vitamin d2 from plants and d3 from animals -> vitamin d3

- liver then forms calcidiol (circulating form) and kidneys forms calcitriol (active form) via hydroxylation

vitamin D functions

- hormone

- absorption of calcium and phosphorus

- promotes blood levels of calcium by increasing calcium absorption in GI tract, retaining calcium in kidneys, and calcium withdrawal in bones

- calcium deficiencies

parathyroid hormone

hormone that helps regulate calcium levels with vitamin D.

vitamin D's role in calcium

1. low blood calcium

2. vitamin D activates vitamin D in kidneys

3. increases intestinal calcium absorption

4. stimulates calcium release from bone

5. normal blood calcium

6. reduces calcium lost in urine

sources of vitamin D

- animal based foods

fortified milk, egg yolks, liver, fatty fish

exposure to sunlight

vitamin D toxicity

• Hypervitaminosis D

-- Likely result of excess supplementation

-- Increased calcium levels in the blood

then causes hypercalcemia

-- leads to damaging calcium deposits in kidneys, lungs, blood vessels, and heart

vitamin D deficiency

rickets

osteomalacia

osteoporosis

rickets

vitamin d deficiency in children; causes bowed legs from soft bones

osteomalacia

soft bones in adults due to vitamin d deficiency

osteoporosis

bone diseases with decreased density and increased fracture risk

risk factors for vitamin d insufficiency

heart disease, respiratory infections, diabetes, hypertension

Vitamin E

tocopherol & tocotrienols

Vitamin E function

antioxidant

- protects cell membrane

- prevents the oxidation of the bad LDL cholesterol carrier

helps immune function

antioxidant

compounds that neutralizes free radicals and prevents cellular damage.

free radicals

chemical particles with an odd number of electrons

- vitamin E donates an electron to them

Vitamin E and C relationship

vitamin C regenerates oxidized vitamin E, maintaining its antioxidant function.

roles of vitamin E

gamma-tocopherol

- inflammation and cancer

trocotrienols

- bone health, diabetes, heart disease

vitamin E sources

vegetable oils (salad dressings)

nuts and seeds

whole grains

green leafy vegetables

avocados

fortified cereals

vitamin E toxicity

rare

high doses interfere with vitamin K

leads to hemorrhage

Hemmorrhage

excessive bleeding from a ruptured blood vessel

(from low vitamin K or excess vitamin E)

Vitamin E deficiency

rare but associated with cystic fibrosis, nerve degeneration, breaking open of red blood cells

Vitamin K

menaquinone - bacteria in GI tract

phylloquinone - found in green plants (primary source)

Vitamin K function

think Klotting

- major role in coagulation

- acts as a coenzyme

-- aids in bone health: osteocalcin -> binds with calcium

vitamin K sources

THINK GREEN! so green veggies

vitamin K deficiency

-RARELY seen

-infants given vitamin K injection because intestinal tract not yet full of bacteria

- lead to hemmorage

vitamin K toxicity

- not common

- jaundice, reduce effectiveness of drugs

Vitamin K and blood thinners

warfarin: drug that prevents blood clotting

so must keep a consistent intake of vitamin K