Vitamins Flashcards
What is the RDA for Vitamin A?
Retinol Activity Equivalents
RAE 900 mcg/d (M)
700 mcg/d (F)
What is the AI for Vitamin D
19-70 year olds 15 mcg/d
What is the AI for Vitamin K
120 mcg/d (M)
90 mcg/d (F)
excess vitamins A & E antagonize vitamin K
What is the RDA for Vitamin E
15mg/d
may not be the optimal level
What is the RDA for Thiamin (B1)
- 2 mg/d (M)
1. 1 mg/d (F)
What is the RDA for Riboflavin (B2)
- 3 mg/d (M)
1. 1 mg/d (F)
What is the RDA for Niacin (B3)
NE: Niacin Equivalents
16 NE/d (M)
14 NE/d (F)
also 15 mg/d
What is the RDA for B6?
1.3-1.7 mg/d
need varies with protein intake
What is the RDA for B12
2.4 mcg/d
What is the RDA for Folate
400 mcg/d for adults
What are reliable dietary sources for Vitamin A
animal food sources: liver, fish, fish oil, fortified milk, dairy, eggs
carotenoids: dark green veg and yellow-orange veg
What are reliable dietary sources for Vitamin D
animal products: eggs, milk, butter, fatty fish, fish liver oils (D3) fortified milks and cereals (D2)
What are reliable dietary sources for Vitamin K and non-food sources?
Plant foods: green leafy vegetables, broccoli, peas, green beans, vegetable oils, animal tissue, liver milk
intestinal bacteria
What are reliable dietary sources for Vitamin E
Plant Oils: vegetable oil, olive oil, sunflower oil, safflower oil, nuts, seeds, wheat germ
What are reliable dietary sources for Vitamin C
Lemons, limes, organes, red peppers, broccoli
What are reliable dietary sources for Thiamin
Enriched grains (rice) and whole grains, fortified cereals, pork, hotdogs, luncheon meat
What are reliable dietary sources for Riboflavin
Milk products yogurt and cheese-sunlight can destroy riboflavin which is why milk is often in a light-block bottle
enriched or whole grains, liver
What are reliable dietary sources for Niacin
All protein containing foods: beef, pork, poultry, fish, milk, eggs, nuts, peanut, butter, whole and enriched grains
What are reliable dietary sources for B6
Meat fish poultry
whole grains NOT ENRICHED GRAINS
bananas and potatoes
What are reliable dietary source for B12
Organ meat, seafood, meat, poultry, eggs, cheese, milk, fortified cereals
What are reliable dietary source for Folate
Fortified breakfast cereals, grain products, leafy green vegetables, beans, legumes, orange juice, liver
What are the Fat Soluble Vitamins
Vitamins ADEK
What are the Water Soluble Vitamins
Vitamin C, B6, B12, thiamin (B1), riboflavin (B2) niacin (B3) and Folate
How are the status of each vitamin assessed?
Vitamin A: measured in serum-retinal
Vitamin D: measured in serum-25-OH-D
Vitamin E: measured in serum-vitamiin E; also functional test: erythocyte hemolysis
Vitamin C: measured in serum-ascorbic acid
Vitamin K: functional test: measure blood clotting-prothombrin time
Thiamin: Functional assay: transketolase activity in RBC-blood
Riboflavin: Functional assay: gluathione reductase activity in RBC-blood
Niacin: no functional test: measure metabolites in urine
Vitamin B6: Functional test: erythrocyte transketolase, plasma PLP-blood, urinary 4-pyridoxic acid-urine
Vitamin B12: measured in serum-B12, also methymalonic acid-urine
Folate: plasma, serum, RBC, levels (blood) and FIGLU excretion (urine)
Classic Vitamin A deficiency
- Xeropthalmia: irreversible blindness; disease progression: night blindness, decreased mucus production (dryness bacterial invasion), development of Bitot’s spots conjuctiva xerosis, keratomatacia, softening of the cornea, scarring;
- Follicular hyperkeratosis: disease progression, keratin, a protein is normally present in the outer layers of skin (protects the inner layers, maintains moisture), normal epithelial cells in the underlying skin lyaers are replaced with keratinized cells, hair follicles become plugged with keratin, bumpy rough and dry skin,
- impaired immunity;
- poor growth
Classic Vitamin D deficiency
Can be due to:
Low or no exposure to sunlight
-being North of the equator- we can not get vitamin D from skin November-March
-wearing sunscreen or not having any unexposed skin
Decreased Milk Consumption
Fat Malabsorption
Skin Pigmentation
1. Rickets: inadequate bone mineralization (in children) symptoms: bow-legged, outward bowed chest, knobs on ribs, delayed closing of fontanel; rapid enlargement of head, muscle spasms
2. Osteomalacia: symptoms: loss of calcium, soft flexible brittle deformed bones, bending of spine, bowed legs, occurs most often in women, people with diseases of the kidney, stomach, gallbladder, intestine, liver,
AT RISK: older people who stay indoors, women, people with diseases of kidney gallbladder stomach liver
Classic Vitamin K deficiency
- Hemmorrhage (excessive bledding)
- Bone and Hip fractures
AT RISK: newborns have inadequate vitamin K stores and and no gut bacteria therefore get a shot of vitamin k shortly after birth
Also people who take certain anticoagulants, those of have impaired fat absorption, low intake of green vegetables-older adults
Classic Vitamin E deficiency
Anemia is low RBC count
1. Hemolytic Anemia: rupture of RBC membranes
2. Peripheral Neuropathy: due to membrane peroxidation of nerve cells
AT RISK: premature infants and individuals with fat malabsorption
Classic Vitamin C deficiency
- Scurvy: lack of Vit C for 20-40 days symptoms begin when body pool is at 300mg, fatigue, petichiae (pinpoint hemmorhages, bleeding gums, poor wound healing, joint pain
- Anemia
- Atherosclerotic plaques
- Depression
AT RISK: alcoholics, elderly men, individuals with low F/V intake, and smokers
Classic Thiamin Deficiency
- Beriberi “I can’t I can’t” peripheral neuropathy, a. Dry beriberi: weakness, nerve degeneration, irritability poor arm/leg coordination, loss of nerve transmission
b. Wet beriberi: edema, enlarged heart, heart failure
AT RISK: occurs where polished rise is the only stable, occurs within 7 days on a thiamin deficient diet - Wernicke-Korsakoff Syndrome: Involuntary eye movement, double vision, Ataxia: staggering poor muscle coordination, mental confusion “drunken stuppor” when no alcohol present
AT RISK: alcoholics: alcohol diminishes thiamin absorption and increases thiamin excretion coupled with a poor quality diet
Classic Riboflavin Deficiency
- Ariboflavinosis
a. Glossitis: inflammation of tongue so that the deep grooves disappear and the tongue appears more smooth
b. Cheilosis: cracks at the corner of of the mouth
deficient within 2 months
AT RISK: Alcoholics, phenobarbitol use, those without milk intake
Classic Niacin Deficiency
- Pellagra: affects skin, GI tract and CNS, sun exposure worsens condition
Symptoms:diarrhea, dementia, dermatitis, death
Cause: (Meat (fatback protein poor) Maise (corn as main staple in diet) molasses)
occurs in 50-60 days prevented with protein adequate diet
AT RISK: alcoholics, diseases that impair food intake, hartnup disease (disordered trp metabolism) corn as main staple prepared without Alkali, soda lime
Classic B6 deficiency
- Microcytic Hypochromic Anemia: small cells with litter color.
- Seborrheic dermatitis
- Convulsion
- Depression,
- Confusion,
- Reduced immune response,
- Peripheral nerve damage,
AT RISK: alcoholics, infants, elderly, renal patients
Classic B12 deficiency
- Pernicious Anemia: due to absorption failure rather than low intake, due to a lack of intrinsic factor which in turn reduces absorption of B12 available from food. It looks similar to megoloblastic anemia which is caused by low folate.
- Nerve degeneration
- Parasthesia
- Dementia
Irreversible damage - Elevated homocysteine: high levels cause heart disease.
AT RISK: elderly (gastric dysfunction- atrophic gastritis and hypochlohydria). Alcoholics, Gastrectomy patients, intestina tapeworm, strict vegetarians
Classic Folate deficiency
- Megaloblastic anemia: similar symptoms of vitamin B-12 deficiency-huge cells with two copies of everything except DNA. It is a failure of cells to divide without the second copy of DNA. If you take additional folate, DNA will synthesize but it could be masking a B12 deficiency or low intrinsic factor this problem will not be resolved.
- Neural tube defects (NTD) low folate in early pregnancy. Spina Bifida, Anencephaly, increased intake recommended for all women of childbearing age.
3.Elevated risk of heart disease (due to elevated homocysteine levels which can be due to low folate.
Folate B6 & B12 together can lower Hcy levels - Increased cancer risk.
AT RISK: pregnant women, alcoholics, elderly, use of certain medications (aspirins, antacids, oral contraceptives)
Vitamin A Toxicity
Hypervitaminosis A
1. acute: ingestion of 100 x RDA within a short periods (days), intestinal upset, headache, blurred vision, muscular uncoordination
2. chronic: larger intake of vitamin A over longer period, bone/muscle pain, hip fracture, skin disorders, headache, dry skin, hair loss, increased liver size double vision
3. teratogenic: causes spontaneous abortions or birth defects,
AT RISK: pregnant women must limit intake of vitamin A
2. Hypercatonemia: high amounts of carotenoids in the blood stream , turns skins yellow-orange
Vitamin D Toxicity
Hypercalcemia: over absorption of calcium, irreversible calcification of soft tissues (hearts lungs kidneys); narrowing of pulmonary arteries and aorta, facial changes, mental retardation, infants most susceptible, results from excess supplementation (not from sun exposure or milk consumption)
Vitamin E Toxicity
Hemmorrhagic effect in adults
Inhibits Vitamin K metabolism and anticoagulants
In Infants a large oral or IV dose is associated with kidney or liver failure
Vitamin C Toxicity
GI distress (nausea, abdominal cramps, diarrhea, due to high osmotic load)
May increase risk of iron overload in genetically predisposed men
Interference with some diagnoistic medical tests Toxic levels achieved only with SUPPLEMENTATION
Niacin Toxicity
Toxic levels achieved only with SUPPLEMENTATION
Nicotinic Acid supplements cause flushing of skin, itching, GI disturbances, liver damage
Used as a pharmacological agent to lower LDL and raise HDL
B6 Toxicity
Toxic levels achieved only with SUPPLEMENTATION
Toxicity symptoms: depression, fatigue, irritability, headaches, nerve damage causing numbness, muscle weakness, inability to walk, convulsions, skin legions. B6 has been used because of its pharmalogical efficts: PMS depression, carpal tunnel syndrome
Vitamins without UL/Toxicity
B12
Thiamin
Riboflavin
Vitamin K
Where are each of the vitamin stored
A: 90% in liver-reserve adequate for several months
D: Stored in fat tissues or converted to 25-OH in liver
K: limited amount stored in liver
E: adipose tissue, liver, and muscle found in cell membranes (associated with phospholipids
Thiamin: storage is poor-30mg total-skeletal muscles
Riboflavin: small amounts stored in tissues
Niacin: stored in liver
B6: stored in liver and muscle tissue
B12: stored in liver (for years)
Folate: stored in liver
How are the fat soluble vitamins excreted
mainly via bile small amounts in urine
vitamin E may be more equal in terms of excretion in bile and urine
How are the water soluble vitamins excreted
excreted in urine
exception: B12 & Folate excreted in bile as well
Describe Absorption and Transport of Vitamin A
dependent on the fat in the diet, requires bile, digestive enzymes, Absorbed into the cells of th e small intestine via carrier proteins, integrated into micelles, 90% of retinoids can be absorbed, only 3% of carotenoids are absorbed, intestinal cells can convert carotenoids to retinoids
Transported via chylomicrons to the liver, transported from the liver as retinol via retinal-binding protein (RBP) to target tissues
Carotenoids can be transported via VLDL
Describe Absorption and Transport of Vitamin D
In the body, active vitamin D is formed via skin, liver, and kidney. Sunlight converts 7-dehydrocholesterol to previtamin D3 in skin. Liver converts to 25-OH vitamin D3. Kidney converts to 1,25-(OH)2 vitamin D3 (active = calcitriol). 80% incorporated into micells, absorbed in the small intestine, transported via chylomicrons and then through lymphatic system.
Describe Absorption and Transport of Vitamin K
Absorption requires biles and pancreatic enzymes
40-80% absorbed
Menaquiones synthesized by the bacteria in the colon about 10% absorbed
Incorporated into lipoproteins for transport
Describe Absorption and Transport of Vitamin E
Absorption requires bile, pancreatic enzymes, and dietary fat
Incorporated into chylomicrons then incorporated into lipoproteins in the liver
Describe Absorption and Transport of Vitamin C
Ascorbic acid: active transport
Dehydroascorbin acid is passively absorbed
Absorption efficiency decreased with high intakes
Describe Absorption and Transport of Thiamin, Riboflavin and Niacin
Absorbed via active transport, passive if high concentration
Transported in blood
Thiamin-by RBC in blood
Riboflavin-by carrier protein in the blood
Niacin-30% of nicotinic acid is protein bound
Niacin can also be absorbed in small intestine and stomach
Describe Absorption and Transport of Vitamin B6
Dephorphorylated by alkaline phosphatase. Absorbed via passive diffusion. Most taken up by liver. Protein bound in blood (albumin).
Describe Absorption and Transport of Vitamin B12
B12 acts differently during absorption and transport than other water soluble vitamins. It can never be left by itself, it needs an escort (without an escort the bacteria in the GI tract will consume it) 1. Salivary Gland produces R protein 2. food digested in stomach B12 is cleaved from the animal protein and then links to the r protein and forms in the acidic stomach-at the same time instrinsic factor is also released in the stomach 3. in the small intestine intrinsic factor and B-12 link and then B12 is absorbed into blood stream?
Binds to transcobalamin protein for transport
Describe Absorption and Transport of Folate
In foods folate occurs naturally as polyglutamate
Digestion in intestine breaks glutamates off and adds a methyl group
Folate is absorbed and delivered to cells through active diffusion (passive if high intake)
Delivered to liver where it is changed back to polyglutamate form
Describe the general properties of fat-soluble and water soluble properties
Fat Soluble Vitamins
- Soluble in fat and fat solvents
- Intake in excess of daily stored in body
- Small amounts excreted in bile
- Deficiency symptoms are slow to develop
- Not absolutely necessary in the diet every day
- Have precursors or provitamins
- Contains only the elements carbon, hydrogen, oxygen
- Absorbed into lymphatic system
- Needed only by complex organisms
- Some are toxic at relatively low levels (6-10x the RDA)
Water Soluble Vitamins
- Soluble in water
- Minimal Storage of dietary excesses
- Excreted in Urine
- Deficiency symptoms often develop rapidly
- Must be supplied in diet everyday
- Generally do not have precursors
- Contains the elements carbon, hydrogen, oxygen, and some cases others (cobalt and sulphur)
- Absorbed into blood via portal vein
- Needed by simple and complex organism
- Toxic only at megadose levels (>10x RDA usually resulting from supplementation)
What are the different types of Vitamin A
Preformed: Retinods -Retinal -Retinol -Retinoic Acid found in animal products Provitamin A: Carotenoids are precursors of Vitamin A -beta Carotene found in plants
Vitamin A and the Visual Cycle
o In retina of eye Specialized cells called rods and cones responsible for vision in bright line and dim lights
o In cells molecule called rhodopsin which consists of protein called opsin plus a molecule of vitamin A in the retinal form-oriented CIS configuration
o When eye is exposed to bright light molecule rhodopsin splits into opsin and retinal and retinal converted to trans configuration and this sends a signal to the brain of what you just saw
o To complete the cycle the opsin recombines with the cis retinal and forms rhodopsin
o After expose to bright light and bleaching processes not all of the retinal is reused some is lost and must be replenished by body stores
o If one does not have enough stored vitamin A their ability to recover from the bleaching process will be repaired
o Inadequate vitamin A stores can lead to a condition called night blindness or an inability to recover your normal vision after being exposed to bright light
What are the different forms of Vitamin D
Calciferol-in foods
D3 cholecalciferol
D2 ergocalciferol
active form: calcitrol
What are the different forms of Vitamin K
K1 = phylloquinones: plant foods K2 = menaquinones: animal tissues K3 = menadione: Synthetic
What are the different types of Vitamin E
most active form alpha tocopherol; tocopherols (alpha, beta, gamma, delta) and tocotrienols (alpha, beta, gamma, delta)
What are free radicals?
o A free radical or oxidizing agent is a molecule with an unpaired electron and is considered to be highly unstable
o Free radicals are generated in the environment, air pollutants cigarette smoke pesticides also generate in body during normal cell metabolism the ETC actually produces some free radicals and the immune response also produces some free radicals in order to rid the body of some microorganisms
o Can be very destructive to cell components especially lipid membranes DNA and proteins
o When a free radical attacks one of the cell components it generates a chain reaction when a FR comes in contact with another molecule it will take an electron from that molecule and become stable, now this molecule has an unpaired electron and becomes a free radical, it then steals an electron from the next molecule
o This chain reaction can destroy cell membranes, disable cell proteins and cause mutations in DNA
o It is hypothesized that the accumulation of free radical damage over time can lead to development of certain chronic diseases such as cancer CVD and macular degeneration
Define anti-oxidant and what vitamins act as anti-oxidants
an anti oxidant by donating it electron to a free radical and stopping the chain reaction and it does not become a free radical but it can no longer function as an anti-oxidant
Vitamin E & beta-Carotene
what are the types of Vitamin C
Ascorbic Acid (reduced form) & dehydroascorbic acid (oxidized form)
What are the types of Thiamin
Thiamon pyrophosphate (TPP) is coenzyme contains sulfer and nitrogen group
What are the types of Riboflavin
part of coenzymes: Falvin adenine dinucleotide (FAD) & Flavin Mononuclotide (FMN)
What are the types of Niacin
Nictonic Acid, Nicotinimide, Niacinamide & coenzyme forms: NAD, NADH, NADP, NADPH
What are the types of B6?
pyridoxal, pyrodoxine, pyradoxamine, main coenzyme form: pyrdoxal phosphate (PLP)
What are the types of B12?
Cyanocobalamin (free enzyme) Coenzyme forms: methylcobalamin, 5-deoxyadenosylcobalamin
What are the types of Folate?
folate (food source), folic acid (in fortified foods/supplements), folacin. Coenzyme form: tetrahydrofolic acid (THFA) Tetrahydrofolate (THF)
What vitamins are enriched in grains?
B1 B2 B3
Thiamin/RIboflavin/Niacin
Major biochemical/physiological functions of Vitamin A
Vision (know visual cycle), growth & development, cell health & maintenance, reproduction, immunity
Major biochemical/physiological functions of Vitamin D
Regulates blood Ca level (calcitriol, required for Ca absorption); bone growth & maintenance; cell differentiation
Major biochemical/physiological functions of Vitamin E
Antioxidant (prevents propagation of free radical chain reactions by donating an electron to oxidizing agent). Protects PUFAs in cell membrane, prevents cell lysis, cell death. Prevents alteration of cell’s DNA, limits LDL oxidation
Major biochemical/physiological functions of Vitamin K
Convertes glutamate to gamma-carboxyglutamate, synthesizes blood clotting factors, synthesizes bone proteins, blood vessel function
Major biochemical/physiological functions of Vitamin C
Antioxidant in water-based fluids. Synthesis of many compounds in body (collagen, carnitine, NT: trp to seratonin, and dopamine to norepinenphrine, hormones (thyroxine, calcitron, gastrin)). Enhances immune function-protects WBC from oxidative damage. Detoxification of drugs, carcinogens. Reactivates vitamin E.
Major biochemical/physiological functions of Thiamin
Energy metabolism (decarboxylation and coenzyme that catalyzes reaction form pyruvate to Acetyl CoA) Pentose synthesis (transketolation, generates 5C sugars like ribose found in DNA and RNA) Nerve conduction (in nerve cell membraines may regulate nerve impulse transmissions and may affect release of acetlycholine)
Major biochemical/physiological functions of Riboflavin
Energy metabolism. Accepts/donates electrons. Participates in oxidation-reduction reactions (ETC, citric acid cycle, catabolism of fatty acids)
Major biochemical/physiological functions of Niacin
Energy metabolism (glycolysis, TCA, ETC, generation of ATP). Participates in oxidation-reduction reactions.
Major biochemical/physiological functions of Vitamin B6
- Amino Acid metabolism (transamination, deamination, decarboxylation)
- neurotransmitter synthesis: ( NT are derived from AA but to get from AA to NT you need B6) trp to seratonin, tyr to dopamine, his to histamine? Glu, to GABA.
- Heme synthesis (need B6 to develop Heme without Heme you will have a low RBC count
- Homecysteine metabolism: high amounts can cause athersclerosis and icnreased risk of heart disease (also metabolized by B12 and folate)
- Conversion of trp to Niacin
- Carbohydrate metabolism
- Steroid hormone binding action
Major biochemical/physiological functions of Vitamin B12
DNA synthesis, creates the second copy of DNA, B12 and folate have reciprocal functions so improtant in folate metabolism, nerve function-maintains myelin sheath
Major biochemical/physiological functions of Folate
DNA Synthesis: helps dna during cell division to make a seocnd copy. Amino acid metabolism: NT formation & Homecysteine metabolism . B12 helps folate get into the form needed for DNA synthesis
How does the body make Vitamin D from the sun
In the skin sunlight coverts 7-dehydrocholesterol into previtamin D3
In the liver this previtamin D3 is hydroxylated to 25-hydroxy-D3
In the kidneys hydroxylated again to 125 dihydroxy Vitamin D3
Active form of Vitamin D called calcitrial also the hormonal form
Summarize the general differences between macronutrients (carbohydrates, lipids, proteins) and micronutrients (vitamins and minerals)
Macro required in large quantities (g), micro in small (mg, μg). Macro yield energy, while micro do not. All vitamins are essential nutrients (has a specific biological function, removing it from the diet leads to a decline in biological function, and adding it back returns function to normal). The essential macronutrients are glucose, linoleic/linolenic acid, and 9 amino acids.
Describe the population group or groups at risk for water-soluble vitamin deficiencies.
Alcoholics, those taking certain medications, smokers (vitamin C), pregnant women (folate), elderly (B12)
Describe the population group or groups at risk for fat-soluble vitamin deficienci
Fat-soluble vitamin deficiencies likely in those with fat malabsorption syndromes (alcoholics, those on certain medications, those with intestinal diseases like cystic fibrosis, celiac disease, Crohn’s disease). Vitamin D deficiency likely in populations exposed to little or no sunlight. Newborns very susceptible to vitamin K deficiency because no gut bacteria (therefore given a shot at birth)
What is the RDA for Vitamin C
90 mg/d (M)
75 mg/d (F)
Vitamins responsible for energy metabolism
thiamin
riboflavin
niacin
b12
Vitamins responsible for blood formation and clotting
B6
b12
folate
K
Vitamins responsible for protein and AA metabolism
b6 folate b12 C riboflavin (indirect)
Vitamins responsible for bone health
A
D
K
C
Vitamins responsible for gene expression
A
D
vitamins that act as anti oxidants
E
C (likely)
Carotenoids
Riboflavin (indirect)
