Vitamins

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


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 )


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


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


BIOTINfunction: coenzyme in

synthesis of fat, glycogen and amino acids

deficiency: S/SX: scaly red skin rash, hair loss, loss of appetite, depression


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


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

Vitamins

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