Fat Soluble Vitamins Flashcards
List the fat soluble vitamins
A, D, K, E
Main difference between macronutrients and micronutrients
Micronutrients are non-energy yielding
General properties of fat soluble vitamins
Soluble in fat and fat solvents Excess stored in body Excreted via bile Deficiencies are slow to develop Not necessary to consume daily Have precursors or provitamins Contain only CHO Absorbed via lymphatic system Some are toxic
Which fat soluble vitamin cannot be stored in the body?
Vitamin K
Chemical Name for Vitamin A
Preformed: Retinoids
ProVitamin: Caratenoids (main form beta-carotene
Vitamin A RDA
900 μg for men; 700 μg for women (preformed)
Foods with Vitamin A (retinoids)
animal products- liver, eggs, fish, fish oils, fortified milk and dairy
Foods with Vitamin A (caratenoids)
dark green and yellow/red vegetables, some fruits
Which fat soluble vitamin cannot be stored in the body?
Vitamin K
Chemical Name for Vitamin A
Preformed: Retinoids
ProVitamin: Caratenoids (main form beta-carotene
Vitamin A RDA
900 μg for men; 700 μg for women (preformed)
Foods with Vitamin A (retinoids)
animal products- liver, eggs, fish, fish oils, fortified milk and dairy
Foods with Vitamin A (caratenoids)
dark green and yellow/red vegetables, some fruits
General Digestion, Absorption, Transport, Storage and Excretion of Fat Soluble Vitamins
Enzymes (especially from the pancreas) release vitamins from food during digestion –> bile aids in absorption in the SI along with dietary fat –> primarily stored in liver –> minimal excretion via bile
Vitamin A absorption
Dependent on fat in the diet; requires bile, digestive enzymes, integration into micelles
- 90% retinoids absorbed
- 3% caratenoids absorbed
The Visual Cycle
Cones: responsible for vision under bright lights. translate objects to color vision
Rods: responsible for vision in dim lights, translate objects to black and white
Vitamin A Storage
90% in liver
Vitamin A Excretion
mostly stored, minimally excreted via bile
Vitamin A Functions
Growth and Development
vision
reproduction
immunity
Vitamin A and Vision
Retinal turns visual light into nerve signals
Retinoic acid helps maintain normal differentiation of cells in the eye (cornea, rod cells)
Vitamin A and Immune Function
maintains epithelial cells- skin’s first line of defense
Rhodopsin
a molecule in rod cells that contain opsin and cis-retinal (Vitamin A)
Rhodopsin and bleaching process
Exposure to bright light cis-retinal to trans-retinal Opsin released from retinal Signal to brain Retinal reused, some lost Rhodopsin reformed
Vitamin A and growth and development
Retinoic acid is necessary for cellular differentiation
Embryo development and gene expression
Synthesis of bone protein and bone enlargement
Vitamin A and cell health and maintenance
Retinoic acid influences how cells differentiate and mature
Vitamin A and Immune Function
maintains epithelial cells- skin’s first line of defense
Vitamin A assessment
serum (blood)
Xerophthalmia
Irreversible blindness due to Vitamin A deficiency
Night blindness –> decreased mucus production –> Development of Bitot’s spots, conjunctival xerosis –> Keratomatacia (softening of cornea)–> scarring
Follicular hyperkeratosis
Vitamin A deficiency: Normal underlying epithelial cells are replaced with keratinized cells and hair cells become plugged with keratin, rough and bumpy skin
Hypervitaminosis A
Vitamin A toxicity
Acute: headache, stomach ache, blurred vision, muscular uncoordination
Chronic: bone/muscle pain, hip fractures, skin disorders, hair loss, increased liver size
Teratogenic: spontaneous abortion and birth
defects
Hypercarotenemia
Beta-carotene toxicity: skin turns yellow/orange
Vitamin A assessment
serum (blood)
Vitamin D chemical name
califerol
food sources of Vitamin D
Vitamin D3: eggs, milk, butter, fatty fish, fish liver oil
Vitamin D2: plants, fortified milk and cereals
Vitamin D RDA
19-50 years: 15 mg/day (600 IU/d)
Functions of Vitamin D
Regulates blood calcium levels
Calcitrol: Increased intestinal absorption of Ca, helps release Ca from bone into blood (with PTH) = higher Ca level in blood
Bone growth and maintenance
Cell differentiation: cancer cells (skin, breast, bone); skin cells, linked to reduction in development of breast, colon, & prostate cancers
Vitamin D absorption
80% consumed is absorbed in micelles with dietary fat in small intestine
Vitamin D transport:
via chylomicrons via lymphatic system
Vitamin D storage
mainly in stored in fat tissue, or converted to 25-OH in liver and circulated throughout body. When stores are low kidneys are used to form D
Measuring Vitamin D
Measure serum (blood) Serum 25-(OH)-D Levels will vary with season, latitude, age
Functions of Vitamin D
Regulates blood calcium levels
Calcitrol: Increased intestinal absorption of Ca, helps release Ca from bone into blood (with PTH) = higher Ca level in blood
Bone growth and maintenance
Cell differentiation: cancer cells (skin, breast, bone); skin cells, linked to reduction in development of breast, colon, & prostate cancers
Vitamin D deficiency
Can be due to: Low or no exposure to sunlight Decreased milk consumption Fat malabsorption (Skin pigmentation)
Rickets
Osteomalacia
Rickets
Vitamin D deficiency: Inadequate bone mineralization in children
Symptoms:
Bowed legs
Outward bowed chest
Knobs on ribs
Delayed closing of fontanel; rapid enlargement of head
Muscle spasms
Vitamin K non-food sources
synthesized by bacteria in colon (10% absorbed)
Measuring Vitamin D
Measure serum (blood) Serum 25-(OH)-D Levels will vary with season, latitude, age
Vitamin K Chemical Name
Quinones
K1: phylloquinones
K2: menaquinones
K3: menadione
Vitamin K AI
Men: 120 micrograms/day
Women: 90 micrograms/day
Vitamin K food sources
K1: green leafy vegetables, broccoli, peas, green beans, vegetable
K2: animal tissues (liver, milk; intestinal bacteria)
Vitamin K non-food sources
synthesized by bacteria in colon
Vitamin K absorption
requires bile and pancreatic enzymes; 40-80% of dietary K is absorbed; 10% of synthesized (from bacteria)
Vitamin K transport
via lipoproteins
Vitamin K storage
limited amount stored in liver
Who is susceptible to Vitamin K deficiency
newborns
people taking certain anticoagulants or antibiotics
impaired fat absorption
low intake of green vegetables (in older adults)
Vitamin K functions
Converts glutamate to gamma-carboxyglutamate so that it is able to bind with Ca
Synthesis of blood clotting factors (prothrombin & others)
Synthesis of bone proteins
Blood vessel functions
Vitamin K and bone formation
Synthesis of bone gla proteins
Osteocalcin secreted by osteoblasts
Matrix gla protein found in protein matrix of bone
Ca binding properties
Vitamin K deficiency
Impaired fat absorption, hemmorage, bone/hip fractures
Vitamin K toxicity
Not common, but can affect anticoagulant drugs
Who is susceptible to Vitamin K deficiency
newborns
people taking certain anticoagulants or antibiotics
impaired fat absorption
low intake of green vegetables (in older adults)
Transport of Vitamin E
via chylomicrons to liver where it is incorporated into liproproteins
Vitamin E Chemical Name
Tocopherols; Tocotrienols
main type: alpha tocopherol
Vitamin E RDA
15 mg/day for women and men
Foods high in Vitamin E
Plant oils, nuts & seeds, wheat germ, asparagus
Vitamin E additional functions
Prevents cell lysis
Protects PUFAs within the cell membrane and plasma lipoproteins
Prevents the alteration of cell’s DNA and risk for cancer development
Limits LDL oxidation, a contributor to atherosclerosis
Transport of Vitamin E
via chylomicrons
Storage of Vitamin E
stored in adipose tissue, muscle, liver
found in cell membranes (associated with phospholipids)
Excretion of Vitamin E
via bile, some in urine
Vitamin E main function
ANTIOXIDANT
donates electron to oxidizing agent and protects the cell from attack by free radicals and interrupts chain reaction in lipid membrane
Vitamin E additional functions
Prevents cell lysis
Protects PUFAs within the cell membrane and plasma lipoproteins
Prevents the alteration of cell’s DNA and risk for cancer development
Limits LDL oxidation, a contributor to atherosclerosis
Vitamin E Deficiency
Hemolytic anemia, Peripheral neuropathy
Hemolytic anemia
Hemolysis, ruptured RBC membranes (Vitamin E deficiency)
Free Radicals and disease
precancerous changes to DNA, oxidation of blood cholesterol initiating steps to heart disease, disabling lipids in cell membranes and proteins
can lead to a variety of diseases
Who is at risk for Vitamin E deficiency
Premature infants (limited stores, rapid growth) People with fat malabsorption
Vitamin E toxicity
Hemorrhagic
Inhibits vitamin K metabolism and anticoagulants
In premature infants, large oral or intravenous dose (10-30 mg E-Ferol) associated with kidney and liver failure.
Measuring Vitamin E in body
Serum vitamin E concentration (blood); Erythrocyte hemolysis test (functional)
Free Radicals
Molecule with unpaired electron, unstable
Include singlet oxygen, H2O2, ·OH, O2·-,O3, NO·
Generated in environment: air pollutants, cigarette smoke, pesticide
Generated in body: normal cell metabolism, immune system
Can destroy lipid membranes, DNA, protein and initiate a chain reaction creating more free radicals
Free Radicals and disease
precancerous changes to DNA, oxidation of blood cholesterol initiating steps to heart disease, disabling lipids in cell membranes and proteins
can lead to a variety of diseases
Antioxidants in food
Vitamin E Glutathione peroxidase (Se) Superoxide dismutase (Cu, Zn, Mn) Catalase Phytochemicals (carotenoids) Vitamin C
**combo is better than any one antioxidant
