Chapter 8 (pt.2): Vitamins (Hill) Flashcards
in what way do vitamins A and D act like hormones?
regulating DNA transcription
Vitamin A and E - required by what animals and have what effects on the body?
required by all animals
may have beneficial effects on immunity
deficiency of fat soluble vitamins accompany what condition?
fat malabsorption
Source of Vitamin A and carotenoids
plants do not contain vitamin A (retinol) but they do contain carotenoids which can be split in the body to form retinol except in cats and they therefore must be given retinol in the diet.
hay and corn - contain carotene
cod liver oil - retinol
function of Vitamin A (retinol) and carotenoids
- light pigment rhodopsin aka night vision
- affects DNA transcription by:
- promoting skin and mucosal differentiation and proliferation. carotenoids have been used at high doses to treat solar dermatitis and squamous cell carcinoma in dogs
- increased immunity
- carotenoids act as antioxidants
Vitamin A (retinol) and carotenoids: deficiency
- night blindness
- **common in seed-eating birds: cutaneous abscesses
- poor heat tolerance, emaciation, weakness, mastitis, etc
Vitamin A (retinol) and carotenoid: toxicity
- cervical spondylosis in cats fed exclusively liver*
- and in anteater pet foods*
- polar bear liver contains very high concentrations*
Vitamin D sources
- dogs and cats cannot synthesize in skin so must have external sources*
- formed in skin by action of sunlight
- hays, fish liver oils, irradiated yeast
what species of animal cannot use Vitamin D2 and must use Vitamin D3? ***
***new world monkeys and poultry - must Vitamin D3 only!
Vitamin D function
hormone which regulates Ca and P absorption from intestine and resorption from bone and Ca absorption in kidney
Vitamin D deficiency
- **Rickets seen in animals deprived of sunlight - especially reptiles
- chronic renal failure
Vitamin D toxicity
excess supplementation in pet foods or owners
rodenticide poisoning
Vitamin E sources
vegetable oils, wheat germ
Vitamin E function
Vitamin E (tocopherol) acts as an antioxiant in pet food but is oxidized over time. tocopherol acetate in pet food is converted to Vitamin E in the body where its used as an antioxidant but has no oxidant activity in food before transformation.
- immune stimulant
Vitamin E deficiency
- myopathy, poor reproduction, mastitis
- common in fish-eating mammals**
- ** possibly responsible for steatitis in cats
Vitamin E toxicity
high doses interfere with Vitamin K metabolism and platelet function
therapeutic uses of Vitamin E
is used for any disease where oxidation is part of pathogenesis like reperfusion injury
Vitamin K sources
intestinal bacteria
green plants
Vitamin K function
cofactor in synthesis of clotting factors: 2, 7, 9 and 10
Vitamin K deficiency
symptom is hemmorhage as in Warfarin poisoning
also seen in fat malabsorptoin due to bile duct obstruction and fatty liver disease
what water soluble vitamin is produced in the rumen not an essential nutrient in cattle?
vitamin B
what water soluble vitamin is easily destroyed by heat so “overage” is added to pet food diets to accomodate losses?
vitamin B
Vitamin C sources***
** synthesized by most species except primates, guinea pigs, some bats, some birds (Bulbuls), fish and invertebrates **
Vitamin C function
antioxidant
hydroxylation of proline and lysine in collagen formation*
fibroblast and osteoblast function
important for immunity and carnitine synthesis
Vitamin C deficiency
- “scurvy” - loose teeth, poor wound healing, ruptured capillaries, etc.
- dogs and cats synthesize ascorbic acid in liver
- some say supplementation is needed during times of stress
Vitamin B1 (thiamin) sources
yeast
Vitami B1 (thiamin) function
as the coenzyme for enzymes involved in energy metabolism like : acetyl CoA and succinyl CoA
Vitamin B1 (thiamin) deficiency
* bracken, fish and heart and spleen can contain thiaminases so can induce deficiency in fish eating mammals, birds of prey fed chicks and horses eating bracken**
seen in calves, sheep, greyhounds and cats
***heart failure can be induced by glucose infusion in deficient humans.
signs: ataxia, impaired righting reflexes, impaired vestibulo-ocular reflexes, poorly responsive pupils, ventroflexion of neck, circling, cardiac arrhythmias. pathology is cerbro cortical necrosis
Vitamin B2 (Riboflavin) sources
yeast, milk and alfalfa meal
Vitamin B2 Riboflavin: function
act as coenzymes for FAD and FMN in oxidation/reduction actions
Vitamin B2: riboflavin - deficiency *
poor growth,
angular stomatitis in humans
Vitamin B3 (niacin) : sources
corn, wheat are poor sources
yeast, wheat bran and sunflower and peanut meals are rich sources
vitamin B3 (niacin): function
act as coenzymes for NAD and NAP so involved in all energy reactions
- used to treat hyperlipidemia in humans and in hypocholesterolemic in dogs
Vitamin B3 (niacin): deficiency
dogs fed un-supplemented diets develop pellagra-like lesions “black tongue”
signs: inappetance, poor growth, diarrhea, dermatitis
Vitamin B3 (niacin) toxicity
profound vasodilation
Vitamin B5 (Pantothenic Acid): sources
yeast, milk, molasses
Vitamin B5 (Pantothenic Acid) : function
part of coenzyme A
vitamin B5 (Pantothenic Acid): deficiency
rare
Vitamin B6 (Pyridoxine) sources
yeast, wheat gram, molasses
vitamin B6 (Pyridoxine): function
acts as a coenzyme in amino acid metabolism for ALT and AST
Vitamin B6 (pyridoxine): deficiency
poor growth and inappetence, dermatitis, and neurological signs
Vitamin B12 (cobalamin): sources
microorganisms in feces, yeast and animal byproducts
Vitamin B12 (cobalamin): function
acts as coenzyme for succinyl CoA and methionine
formation of nucleic acids and myelin
Vitamin B12 (Cobalamin): absorption
dependent on intrinsic factor from the stomach and pancreas in dogs and just the pancreas in cats
absorption is carrier mediated in the ileum*
Vitamin B12 (Cobalamin): deficiency
inappetance, poor growth and neuropathies
mild normocytic anemia in giant Schnauzers
*idiopathic malabsorption in Giant schnauzers
what conditions are commonly associated with a mild deficiency in Vitamin B12 (Cobalamin)
- small intestinal disease affecting the ileum
- bacterial overgrowth (bacteria compete for B12)
- pancreatic insufficiency in cats (absence of IF)
- unsupplemented home-cooked diets
Folate : sources
bacteria in small intestine synthesize folate so slight increase in blood levels in dogs with small intestinal bacterial overgrowth
folate: function
precursor of tetrahydrofolate
folate: absorption
* in proximal small intestine*
folate: metabolism
*** bacteria absorb paraaminobenzoid acid (PABA) which is converted to folate and then converted to tetrahydrofolate (folacin) by the enzyme tetrahydrofolate reductase (THFR).
sulfa antibiotics inhibit the first step: trimethoprim and pyrimethamine the second (THFR inhibitors). the cancer drug, methotrexate also inhibits THFR.
folate: defieincy
signs: slow growth, low dividing cells –> anemia, low WBC count
** decreased blood levels in dogs with proximal small intestinal disease**
deficiency can be precipitated by overdose of trimethoprim sulfa antibiotics or methotrexate: use folate to treat sulfa toxicosis and folacin to treat trimethoprim/methotrexate toxicosis
horses not on pasture may be deficient in folate
Biotin sources
yeast, rice bran
biotin: function
coenzyme of carboxylases involved in fat and carb metabolism:
pyruvate –> oxaloacetate
acetyl CoA –> malonyl CoA
priopionyl CoA –> methylmalonyl coA
Biotin: deficiency
cats fed experimental diets containing raw egg whites were deficient in biotin
signs include: poor growth, poor haircoat, dermatitis
Choline: sources
yeast
poor source: grains
choline: function
methyl donor in phosopholipid metabolism and part of acetylcholine
choline: deficiency
* methionine can act as an alternative methyl donor so choline is probably not required if sufficient methionine is provided above amino acid requirements*
signs: poor growth and hepatic lipidosis
has been recommended as part of treatment for hepatic lipidosis in cats*
Vitamin like molecule: inositol
sources
biosyntehsis
free in animal tissue
as phytate plant tissue
vitamin like molecule: Inositol
function
second messenger in cells
phospholipids
vitamin-like molecule: Inositol
minimum requirement in what species?
in cats because experimental diets all contained some inositol
Inositol supplementation
recommended for fatty liver in cats
decreased nerve conduction in diabetic rats
vitamin-like molecule: pyrroloquinalone quinone (PQQ, ‘Q10’):
sources
synthesis by cells and ubiquitous in diet
PQQ, ‘Q10’
function
required for grwoth in rodents, antioxidant, may reduce the incidence of athersclerosis in humans
