Vitamins Flashcards
Hydrolized in the stomach from the protein complexes found in food
Vitamins
Most of the water soluble vitamins are absorbed in the
Upper small intestine
An exception because it is absorbed in the ileum
B12
Absorbed directly into the portal vein and transported to the liver, where they are either stored (B12) or sent out into circulaiton
Water soluble vitamins
Absorbed with monoglycerides and fatty acids
Fat soluble vitamins
Requires bile salts and formation of mixed micelles
Fat soluble vitamin absorption
Fat soluble vitamins are packaged into
-enter lymphatic system before entering the blood
Chylomicrons
What are the fat soluble vitamins
A,D,E, and K
What are the 4 forms of Vitamin A?
Beta-carotene, retinal, retinol, retinoic acid
Beta-carotene is found in
Plant foods
Retinyl esters are found in
Animal foods
What is the Retinol Activity Equivalent (RAE) of 12 ug Beta-carotene?
1 ug retinol
Vitamin A’s two main functions are
Vision and cell differentiation
Essential for seeing black and white (“rod” cells in retina)
Vitamin A
Vitamin A is particularly important for night vision and recovery of sight after a
Flash of bright light
Important for the maturing of “epithelial cells”, such as those in the intestine and skin
Vitamin A
Vitamin A is Important for the synthesis of
Lymphocytes and antibodies
A mild form of Vitamin A deficiency is
Night blindness
What are three severe forms of vitamin A deficiency?
Xeropthalmia, Hyperkeratosis, and Infections
Damage to corneas, dry eyes, scarring, blindness
Xeropthalmia
Increased keratin synthesis in skin and nails
Hyperkeratosis
What are the two forms of vitamin D?
D2 (Ergocalciferol) and D3 (Cholecalciferol)
The chemical difference between D2 and D3 is a
Double bond in the side chain of D2
What are the three major functions of Vitamin D?
Calcium homeostasis, gene expression, and cell differentiation
Increases calcium absorption and bioavailability and decreases calcium excretion by the kidneys (urine)
Vitamin D
Vitamin D increases calcium release from
Bones
Vitamin D deficiency is essentially the same thing as
Calcium deficiency
Vitamin D deficiency in children leads to
Rickets
Causes brain abnormalities such as a hyperintense signal in the periventricular white matter of the brain
Low Vitamin D
Vitamin D deficiency increases the rate of
Alzheimer’s and Dementia
The type of vitamin K found in plant sources and supplements
-mostly single bonds on its side chain
Phylloquinone (Vitamin K1)
The type of Vitamin K produced by bacteria in the large intestine
-side chain consists of alternating double and single bonds
Menaquinone (Vitamin K2)
Man-made “pro-vitamin” version of vitamin K
-side chain is a single CH3
Menadione (Vitamin K3)
Vitamin K functions in
Blood clotting
What is a medication that inhibits Vitamin K’s clotting abilities
Warfarin (coumadin)
Vitamin K and Calcium are needed for the activation of
Clotting factors
Clotting factors convert prothrombin to
Thrombin
Catalyzes the conversion of fibrinogen to fibrin
Thrombin
Fibrin forms
Blood clots
Catalyzes the conversion of inactive osteocalcin to active osteocalcin which forms hydroxyappetite in bone
Vitamin K
A major consequence of vitamin K deficiency is
Uncontrollable bleeding
Vitamin K deficiency is rare in adults and more common in
New borns
At birth, all newborns are given
Vitamin K injections
Can occur in children and adults with fat malabsorption diseases
Vitamin K deficiency
Prolonged use of antibiotics kill large intestine bacteria which can result in
Vitamin K deficiency
What is the most biologically active form of Vitamin E?
a-tocopherol
Vitamin E functions predominantly as an
Antioxidant
Protects biological membranes against free radicals especially important to tissues exposed to oxygen (e.g. lungs and red blood cells)
Vitamin E
Vitamin E works best in conjunction with
Vitamin C and Selenium
Protects DNA from oxidative damage (may reduce risk of cancer)
Vitamin E
Vitamin E may protect against
Cataracts and heart disease
Rare, but occurs in infants fed formula with too little vitamin E, and in cystic fibrosis (fat malabsorption disorder)
Hemolytic Anemia
Weakened and ruptured blood cells caused by vitamin E deficiency
Hemolytic Anemia
Can cause neuromuscular problems, neuromuscular pain, loss of coordination
Vitamin E deficiency
What are the two forms of Vitamin C?
L-ascorbic acid and L-dehydroascorbic acid
Serves as an antioxidant, reduces Iron, chromium, and copper, and helps synthesize important molecules
Vitamin C
Increases absorption and bioavailability and reduces superoxide (bad oxygen) to hydrogen peroxide (not so bad oxygen)
Vitamin C
Important for fatty acid metabolism and energy production
-synthesized by vitamin C
Carnitine
Amino acid synthesized from vitamin C
Tyrosine
Vitamin C is also important in the synthesis of
Neurotransmitters, hormones (particularly GI), and collagen
Reduces iron from Fe3+ to Fe2+
-which increases the absorption and bioavailability of iron
Vitamin C
Vitamin C deficiency causes
Scurvy
Characterized by bleeding gums, skin irritation, bruising, and poor wound healing
Scurvy
Cured scurvy with lemons and limes in British sailors (origin of the nickname “limeys”)
James Lind
