vitamins
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VITAMINSBIOCHEM LEC
WK 5
VITAMINS VITAMINS- essential organic molecules
needed in very small amounts for cellular metabolism
Primary Deficiency of a Vitamin- occurs when the vitamin is not consumed in sufficient amounts to meet physiologic needs
Secondary Deficiency- develops when absorption is impaired or excess excretion occurs
VITAMINSCategoriesWater Soluble Vitamins- Vitamin B Complex, Choline, Vitamin CFat Soluble Vitamins- Vitamins A, D, E, KFood Sources: Almost all foods, yet NO one food group is a good source of all vitamins; fresh fruits and vegetables are particularly rich sources
WATER SOLUBLE VITAMINS THIAMINE (B1) functions: to serve as coenzyme in
energy metabolism; role in nerve functioning related to muscle actions
RDA: 1.2 mg for men/ 1.1 mg for women Deficiency: BERI-BERI—2 Types WET- manifests with edema affecting
cardiac function DRY- affects the CNS, producing
paralysis and extreme muscle wasting Toxicity: non-toxic; excess is excreted in
urine
WATER SOLUBLE VITAMINS
RIBOFLAVIN (B2) function: coenzyme in the release of
energy from nutrients sensitive to light RDA: 1.3 mg for men/ 1.1 mg for women Deficiency: ARIBOFLAVINOSIS—S/SX CHEILOSIS- lips become swollen and
cracks develop in corners of the mouth GLOSSITIS- inflammation of the tongue
WATER SOLUBLE VITAMINS
NIACIN (B3) functions: coenzyme for many enzymes;
critical for glycolysis and Kreb’s cycle occurs naturally in 2 forms: NICOTINIC
ACID and NIACINAMIDE RDA: 16 NE for men/ 14 NE for women Deficiency: PELLAGRA—3D’s ( Diarrhea,
Dermatitis, Dementia )
WATER SOLUBLE VITAMINS
PYRIDOXINE (B6) functions: coenzyme in the metabolism
of amino acids and CHON 3 forms ( pyridoxine, pyridoxal,
pyridoxamine ) all can be converted to the coenzyme pyridoxal phosphate for use in the body
RDA: 1.3 mg for men and women Deficiency: S/SX: dermatitis, altered
nerve function, weakness
WATER SOLUBLE VITAMINS FOLATE function: coenzyme in reactions involving the
transfer of 1-Carbon units during metabolism 4 forms ( folate, folic acid, folacin and
pteroylglutamic acid ) for folate to be maintained for use in the
body, Vitamin B12 must be available folate has a role in proper formation of fetal
neural tubes (brain and spinal cord development)
RDA: 400 mcg for men/women 600mcg for pregnant women
Deficiency: megaloblastic anemia—large RBC that cannot carry oxygen
WATER SOLUBLE VITAMINS
COBALAMIN/CYANOCOBALAMIN (B12) functions: coenzyme in nucleic acid
metabolism; needed for maturation of RBC
absorption of Vitamin B12 relies on an intrinsic factor (IF) a substance produced by stomach mucosa
deficiency: Pernicious Anemia- inadequate RBC formation caused by lack of IF in the stomach
WATER SOLUBLE VITAMINS
BIOTINfunction: coenzyme in
synthesis of fat, glycogen and amino acids
deficiency: S/SX: scaly red skin rash, hair loss, loss of appetite, depression
WATER SOLUBLE VITAMINS
PANTOTHENIC ACID function: for metabolism of CHO, FATS
and CHON deficiency: do not occur in nature CHOLINE function: needed for synthesis of
acetylcholine, a neurotransmitter, and lecithin( phospholipid)
deficiency: rare
WATER SOLUBLE VITAMINS
ASCORBIC ACID ( VITAMIN C ) functions: collagen synthesis and other
CT; antioxidant; iron absorption; coenzyme
RDA: 90 mg for men/ 75 for women/ 125 mg for smokers
Deficiency: SCURVY: S/SX—inflammation of CT, gingivitis, muscle degeneration, bruising and hemorrhaging as the vascular system weakens
FAT SOLUBLE VITAMINS VITAMIN A functions: component of visual
pigments; needed for maintenance of epithelial tissues; antioxidant
RDA: 900 mcg RAE for men/ 700 mcg RAE for women
Deficiency: XEROPHTHALMIA—night blindness progressing to a hard, dry cornea (keratinization) resulting in complete blindness
FAT SOLUBLE VITAMINS VITAMIN D function: aid in absorption and use of
calcium and phosphorus; promotes bone growth
precursor: 7-dehydrocholesterol (found in the skin)
active form: 1,25- dihydrocholecalciferol deficiency: RICKETS- a childhood
disorder caused by Vitamin D or Calcium deficiency that leads to insufficient mineralization of bone and tooth matrix
FAT SOLUBLE VITAMINS VITAMIN E (TOCOPHEROLS) function: antioxidant RDA: 15 mg TE for men/women Deficiency: rare VITAMIN K function: cofactor in the synthesis of
blood clotting factors deficiency: inhibits blood coagulation
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