Vitamins Flashcards
Retinoids
- preformed Vitamin A
- exist in 3 forms that can be interconverted
- liver, fish oils fortified dairy products, and eggs
Carotenoids
- provitamin A (some converted to Vitamin A)
- dark green, yellow, orange, red veggies, and fruits
- yellow-orange pigment in fruits and vegetables
- alpha, beta carotene and beta cryptoxanthin
Functions of Vitamin A
- growth and development
- cell differentiation
- vision
- immune function
-dermatology
Immune function Vitamin
- vitamin A
- protect entry of pathogens into epithelial barriers
- cellular immunity (function of immune cells)
- antibody protection
- increased infection = early symptom of vitamin A deficiency
Cell differentiation vitamin
- vitamin A
- process of directing stem cells to develop into specialized cells with unique functions
- retinoids bind to retinoid receptors RXR and RAR which bind to specific DNA sites -> direct cell differentiation
growth and development vitamin
- vitamin A
- involved in the development of eyes, limbs, cardiovascular system, nervous system, epithelial cells and mucous forming cells
- lack of vitamin A = birth defects and fetal mortality
Dermatology vitamin
- high doses
- treatment for psiorasis or acne
- accutane or retina A
Vision vitamin
- vitamin A
- retinal is needed in the retina to help convert light energy to nerve impulses in the retina, photosensitive cells contain rhodopsin
- repeated small losses of retinal, need for replenishment
Non-provitamin A Carotenoid Functions
- antioxidants, protect against macular degeneration, cancers, Cardiovascular disease
Vitamin A deficiency
- rare in NA
- major problem in developing countries
- night blindness, irrevesrsible blindness (xerophthalmia), follicular hyperkeratosis (skin)
- increased risk of disease and death
- maternal mortality
Vitamin A toxicity
- hypervitaminosis A
- 3 types (acute, chronic, teratogenic)
- teratogenic = spontaneous abortion and birth defects
- liver damage
Vitamin D
- “conditional” vitamin
- prohormone
- fatty fish, cod liver oil, fortified dairy products, fortified breakfast cereals
Vitamin D from the Sun
- depends on lots of factors
- prolonged exposure to sun will not result in toxic amounts bc excess amounts of previtamin are degraded
Vitamin D3 pathway
- sunlight changes 7-dehydrocholeterol in skin to cholecalciferol (Vitamin D3)
- travels to liver and then kidneys, where converted to bioactive form (calcitriol)
- synthesis regulated by parathyroid hormone and kidneys
Functions of vitamin D
- calcitriol is the active form
- maintain blood levels of ca and p (increase absorption of calcium, release ca and p from the bone)
- regulate immune function
- regulate the cell cycle
- reduce risk of chronic diseases (diabetes, hypertension, dementia, cancer)
Vitamin D Deficiency Diseases
- rickets (children, bones fail to calcify normally and bend)
- osteomalacia (“soft bones”, adults)
Vitamin E
- plant oils, wheat germ, avocado, almonds, peanuts, sunflower seeds
- main source is alpha-Tocopherol
Vitamin E function
- antioxidant
- stops the lipid peroxidation of cell membrane and lipoproteins caused by free radicals
- as vitamin E is “used up” during reaction, must be regenerated by reducing agents such as vitamin C
Vitamin E needs and toxicity
- hemolysis prevention
- excessive amounts can interfere with vitamin K’s role in blood clotting = hemorrhage
Vitamin E deficiency
- hemolytic anemia
- preterm infants, smokers, and those with fat malabsorption are the most susceptible
- immune function impairment and neurological changes
Vitamin K
- menaquinones (k2) = animal sources, synthesized by bacteria in colon, fish oils and meats
phylloquinones (K1) = main dietary form, green leafy vegetables, broccoli, peas, and green beans, veggie oils, most biologically active
Vitamin K functions
- calcium binding
- enzymes (carboxylation)
- synthesis of blood clotting factors (koagulation)
- metabolism/activation of bone proteins (osteocalcin)
Vitamin K Deficiency
- newborns have a sterile intestinal tract, single dose of vitamin K given at birth, long term antibiotic use, fat malabsorption
Vitamin K Toxicity
- no UL
- limited storage, more readily excreted
Vitamin B1
Thiamin
food sources of thiamin
found in small amounts in wide variety of foods
functions of thiamin
- coenzyme form (TPP) *
- conversion of pyruvate to acetyl CoA (TCA cycle)
- coenzyme in reactions to form pentoses for DNA and RNA
thiamin deficiency and causes
peripheral neuropathy and weakness
alcoholism, poor diet, malnourished
beriberi
Beriberi
- Wet = nervous system and cardiovascular system
- Dry and Wernicke Korsakoff syndrome = nervous and muscular system
- causes= alc, poor diet, malnourished
wernicke korsakoff
- mainly in heavy alcohol users
- alcohol decreases thiamin absorption, increases thiamin excretion, causes abuser to consume poor diet
- ataxia (low coordination), visual disturbances, confusion, apathy
- can occur rapidly
- emotional disturbances and impaired cognition
- brain damage in thalamus and hypothalamus
B2
riboflavin
riboflavin functions
- coenzymes (flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD))
- energy metabolism (TCA cycle, Beta-oxidation, shuttles H atoms to the electron transport system), antioxidant function (glutathione synthesis)
- activate other B-vitamins
ariboflavinosis
- riboflavin deficiency
- primarily affects the mouth, skin, and red blood cells
- inflammation of throat, mouth (stomatitis), tongue (glossitis)
- cracking around the corners of mouth (angular cheilitis)
- moist, red, scaly skin (seborrheic dermatitis)
B3
Niacin
niacin in foods
- can be synthesized from tryptophan
niacin forms and functions
nicotinic acid and nicotinamide
coenzymes = nicotinamide dinucleotide (NAD+)
nicotinamide adenine dinucleotide phosphate (NADP+)
- required for catabolism of macros + alc
- redox reactions
- more than 200 reactions
niacin toxicity
- “niacin flush”
- potential health benefits of large amts of nicotinic acid (lower TG and increase HDL)
niacin deficiency
pellagra
- dermatitis
- diarrhea
- dementia
- death
food sources of pantothenic acid
- widespread in foods
- readily destroyed by freezing, canning, and refining
- meat, milk, and vegetables
B5
pantothenic acid
functions of pantothenic acid
- component of coenzyme A (CoA) -> formation of AcCoA
- part of Acyl carrier protein (required to synthesize fats)
B6 in foods
- meat fish poultry, fortified cereals, bananas, potatoes
B6 functions
- metabolism: PLP coenzyme involved in amino acid metabolism = transamination, glycogenolysis
- synthesis of compounds: heme (hemoglobin, carries oxygen), histamine, neurotransmitters (serotonin), nucleic acids, ,vitamins (niacin)
- three forms
Vitamin B6 deficiency
- rare
- microcytic hypochromic anemia
- hypochromic (less hemoglobin in each RBC)
- microcytic (smaller size of each RNC) anemia
Vitamin B6 upper level
- irreversible nerve damage
- stored exclusively in muscle tissue
Vitamin B7
biotin
biotin functions
- coenzyme in carboxylase reactions (incorporate Co2 into a substrate)
- needed for macro metabolism
- TCA cycle, gluceoneogenesis, FA synthesis, AA breakdown
biotin sources
- can synthesize by microbes, widespread in food
biotin deficiency
- biotinase enzyme deficiency, excessive consumption of raw eggs
egg white injury
- excessive consumption of raw egg white
- avidin binds to and inactivates biotin
avidin destroyed by heat
B4
choline
choline
- can be obtained in the diet and synthesized in cells
functions of choline
- component of phospholipids *
- precursor for acetylcholine
- helps export VLDL from liver
- helps carnitine move fatty acids into the cells*
folate
folate in foods and folate supplements
folate coenzyme
- DNA synthesis (converts uracil to thymine) *
-converts B12 to coenzyme form * - AA metabolism
- regeneratees methionine from homocysteine
- neurotransmitter synthesis
folate needs
1 DFE (daily folate equivalents) = 1 mcg food folate =0.6 folic acid taken w/food
folade deficiency (preg)
neural tube defects
- spina bifidia, anecephaly
- day 20~28 post conception = development of spinal cord
folate deficiency
- affects cells synthesizing DNA
- short life span and rapid turnover bc RBCs don’t divide normally and remain large and immature
- megaloblasts = remain in bone marrow
- macrocytes = found in bloodstream
- megaloblastic, (Macrocytic) anemia
B12
cobalamin
b12 sources
- naturally in animal products only!
b12 functions
- forms 2 coenzymes (methylcobalamin, 5-deoxyadenosylcobalamin)
homocysteine -> methionine - fatty acid metabolism
b12 excess
- stored in liver, providing 2-3 years of storage
absorption of vitamin b-12 requires
R protein and intrinsic factor
b12 deficiency
- macrocytic anemia, neurological changes, elevated plasma homocysteine
vitamin c
ascorbic acid, not a B vitamin but close
food sources of vit c
- vulnerable to heat and oxy
- used as antioxidant by food manufacturers
- citrus fruits, peppers, green veg
vit c functions
- antioxidant activity
- collagen synthesis (matrix for bone nad tooth formation)
- enhances none-heme iron absorption
vit c intake
- smoking increases intake
vit c deficiency
- scurvy
- gums bleed easily around teeth
- capillaries under skin break spontaneously
- collagen
