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Flashcards in Vitamins And Minerals Deck (36):
1

Water soluble (Non-B)

Absorbic Acid

2

Water soluble (B-Complex)

-Energy releasing
B1- thiamine
B2- riboflavin
B3-niacin
Biotin
Pantothenic acid
-Hematopoietic: Folic acid, B12
-Others - B6-pyridoxine, Pyridoxal, pyridoxamine

3

Fat soluble

Vit A - retinol
Vit D - cholecalciferol
Vit E - tocopherols
Via K - phylloquinones, menaquinones

4

Retinoids

-family of compounds related to retinol, vision, growth, reproduction, maintenance of epithelial tissues.

5

Retinol

Found in animal issues

6

Retinal

-oxidation of retinol, can be interconverted

7

Retinoic Acid

-mediates most of actions of retinoids except vision

8

B-carotene

- forms two molecules of retinal

9

Absorption and Transport

- retinol esters in diet, hydrolyzed in intestine----> retinol + FFA
-Reesterified to long chain FA in mucosa and secreted with the chylomicrons
-retinol stored in liver
-transported by plasma retinol binding protein
- receptor mediated uptake in cells - RAR
-activates gene transcription

10

Mechanism of action of Vit A

1. Retinoic acid binds to receptor proteins in nucleus of target tissues
2. Stimulates retinoids specific RNA synthesis
3.RA-receptor protein part of the superfamily of transcription regulators that include (steroid and thyroid hormones, 1,25-dihydroxycholecalciferol)

11

Functions of Vit A

1. Vision - component of visual pigment (rhodopsin) 11-cis retinal bound to opsin
2. Rhodopsin - all trans retinal + opsin + nerve impulse
3. Regeneration
4. Isomeric action of all trans retinal to 11-ICS retinal
5. Spontaneous combination with opsin----> rhodopsin
6. Growth - deprivation results in loss of appetite, slow bone growth, CNS damage
7. Reproduction - retinol and retinal support spermatogenesis and prevent fetal resorption. RA inactive in reproduction and vision but promotes growth and differentiation of epithelial tissue.
8. Maintenance of epithelial cells - essential for normal differentiation of epithelial cells

12

Sources of Vit A

-Liver, kidney, cream, butter and egg yolk -preformed Vit A
- Dark green and yellow fruit and veggies are sources of Beta-carotene
-Deficiency - night blindness, xerophthalmia (dryness of conjunctiva and cornea, cornea ulceration follows, which can lead to blindness)

13

Vit A clinical indications

Acne and psoriasis - topical application of all trans retinoic acid (tretinoin) for mild: 13-cis retinoic acid (isotretinoin) orally for severe cases
-prevention of chronic disease- populations with high beta-carotene have decreased heart disease, lung and skin cancer, cataracts and macular degeneration

14

Toxicity of retinoids

1. Hypervitaminosis A - exceeding 7.5 mg/day, dry skin, enlarged, cirrhosis liver, rise in intracranial pressure, excess in pregnancy could cause congenital malformation in fetus
2. Isotretinoin - teratogenic and absolutely contraindicated in women of childbearing potential potential unless severe acne is unresponsive. Prolonged treatment can lead to hyperlipidemia and increased LDL/HDL, increased risk for CVD

15

Vit D

-group of sterols with hormone like functions
-Ergocalciferol and cholecalciferol - preformed D activity
- may be synthesized by light from 7-dehydrocholesterol in skin

16

Function of 1,25-diOH D3

- maintain adequate levels of Ca by:
1. Increasing uptake of Ca by intestine
2. Decreasing Ca loss by kidney
3. Stimulating resorption of bone if necessary to maintain serum Ca

17

Vit D3

-fatty fish, liver, egg yolk

18

Vit D clinical indications

Deficiency - rickets in children cause by incomplete mineralization of bone
-Osteomalacia in adults caused by demineralization of pre existing bones
-RDA - 200IU/day, 800IU/day can reduce osteoporotic fractures
-Renal rickets - from chronic renal failure, inability to form active 1,25-diOH D3
-Hypoparathyroidism - causes hypocalcemia and hyperphosphatemia

19

Vit D toxicity

Most toxic of all vitamins
-fat soluble so it can be stored in your body
Lack of Vit D causes loss of appetite, nausea, thirst, bone resorption and deposition of calcium in organs

20

Vit E

- family of tocopherols, alpha-tocopherols is most active
Primary function - antioxidant in cell lipid components
2) Sources: vegetable oils, liver, eggs
RDA - 10mg/day for men, 8 for women
3) deficiency
-restricted to premature infants
-supplemental not recommended for any prevention of chronic disease

21

Vit K

- blood clotting
- Prothrombin factors 2,7,9 and 10
-not enough K and no carboxylation reaction, not allowing clotting
1) sources of Vit K : cabbage, cauliflower, spinach, egg yolk and liver, also synthesized by gut bacteria
-no RDA
2) toxicity - prolonged administration can produce hemolytic anemia and jaundice in infants

22

B-vitamins

- water soluble, have important functions as coenzymes or constituents of coenzymes essential in metabolism
- whole grains and cereals are good sources

23

Thiamine (B1)

-thiamine pyrophosphate is active form
- acts as a coenzyme in formation or degradation of alpha-ketols and oxidative decarboxylation of alpha-keto acids
-oxidative decarboxylation of pyruvate and alpha-ketoglutarate is important in energy metabolism especially the nervous system
- Wernicke-Korsakoff syndrome - dietary insufficiency or malabsorption

24

Riboflavin (B2)

-water soluble and light sensitive
-function as flavin coenzymes (FAD, FADH)
-Flavins are important for: energy production, metabolism of drugs and toxins, antioxidant, protects against cataract formation, maintains the integrity of mucous membranes, activates B6, promotes nail, skin and hair health
-Deficiency may lead to anemia by impairing Fe absorption, also ariboflavinosis

25

Niacin (B3)

-name from nicotinic acid and nicotinamide
- NAD and NADP serve as coenzymes in redox reactions
- NAD functions in degradation of carbohydrates, fats, proteins and alcohol
-NADP functions in synthesis of fatty acids and cholesterol
Niacin deficiency - pellagra; rash on skin normally exposed to sunlight, and on both sides of the body

26

Pyridoxine- Vit B6

- biologically active as Pyridoxal phosphate
- functions as a coenzyme in reactions catalyzing AA's
Transamination: oxaloacetate +glutaminate -----> aspartate + alpha-ketoglutarate
Deamination: serine -----> pyruvate + NH3
Decarboxylation: histidine -----> histamine + CO2
Condensation: Gly + succinyl CoA----> gamma-aminolevulinic acid
Deficiencies occur with: alcoholics, oral contraceptives, newborns with low B6 formulas, isoniazid treatment of tuberculosis

27

Folic Acid- Vit B9

- essential in one-carbon metabolism for synthesis of number of compounds.
- most common deficiency in US
Tetrahydrofolate - receives one-carbon fragments from donors ( Ser, Gly, His) transfers them to intermediate sin synthesis of amino acids, purines and thimidine

28

Causes of folic acid deficiency

-pregnancy, poor absorption, alcoholism
- treat deficiency with dihydrofolate reductase inhibitors
- folate and neural tube defects result
- folic acid supplementation eliminates the neural defects and anencephaly

29

Vit B12

- cobalamin contains a corrin ring system, cobalt is held in the center of the rings. Commercial preparation is cyanocobalamin
- converts homocysteine to methionine
- converts methylmalonyl CoA to Succinyl CoA
- synthesized only by microorganisms, not plants
- animals obtain B12 preformed in foods derived from other animals
-intrinsic factor, a glycoproteins synthesized by the gastric parietal cells is essential for B12 absorption
-Significant amounts of B12 are stored in the body

30

Deficiency of B12

-pernicious anemia
-CNS symptoms: numbness and tingling, difficulty maintaining balance, depression, confusion, dementia, poor memory, mouth soreness

31

Absorbing Acid - Vit C

-essential coenzyme in hydroxyl action reactions, especially collagen production
- required for wound healing, normal connective tissue maintenance
- facilitates Fe absorption in the small intestine
- water soluble antioxidant
-deficiency results in scurvy characterized by gingival hemorrhage, corkscrew hair with petechiae, periungual hemorrhage, bruising and swollen joints

32

Biotin

-metabolism of carbohydrates, fat, and proteins
-cooperates with blaming B2, B3, and B6
-manufacture of glycogen, fat and detoxification
- source: food, made by the bacteria in the intestines
- essential in cell growth
-chronic eating of raw egg whites limits biotin absorption.

33

Pantothenic acid

-Component of CoA and acyl carrier protein
-CoA contains a thiol group to carry the acyl group as an activated thiol ester
-Sources: eggs, liver, yeast but widely distributed
- No RDA

34

Iron

- essential for hemoglobin and myoglobin production as well as co-factor for many reactions
-deficiency leads to anemia, characterized by pale mucous membranes in the eye and tongue

35

Calcium

- essential for bone mineralization, activator of glycogen degradation, isocitrate dehydrogenase, and pyruvate dehydrogenase phosphatase, insulin release, muscle action, nitric oxide synthase, cell signaling, clotting

36

Iodine

-essential in small amounts to make thyroid hormones
- Iodine deficiency disorders: goiter, cretinism, reduced mental and physical development, increased perinatal and neonatal mortality