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Vitamin E

Vitamin E

memorize.aimemorize.ai (lvl 286)
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Section 1

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Which species is more susceptible to vitamin E deficiency and why?

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Last updated

6 years ago

Date created

Mar 14, 2020

Cards (20)

Section 1

(20 cards)

Which species is more susceptible to vitamin E deficiency and why?

Front

Cats are more susceptible to vit E deficiency than dogs because canned feline diets are typically higher in fat than dogs and are frequently based on fish (esp tuna), containing long chain PUFAs that are prone to lipid peroxidation

Back

What major functions does vitamin E serve in the body (4)?

Front

1) the major lipid-soluble ANTIOXIDANT present in plasma, erythrocytes, and tissues - prevents free-radical or oxidative damage to PUFA in membranes and nucleic acids 2) modulation of prostaglandin synthesis 3) down regulation of protein kinase activity 4) synthesis of xanthine oxidase

Back

What affects dietary vitamin E requirements?

Front

1) rate of production of free radicals 2) PUFA composition of diet/membranes 3) inversely dependent on dietary selenium (Se has role in synthesis of glutathione peroxidase)

Back

What are three causes of vitamin E deficiency? How can they be prevented?

Front

1) fat malabsorption with steatorrhea 2) cholestatic liver disease 3) intestinal resection

Back

How is vitamin E transported and stored in the body?

Front

CM remnants transported to liver --> tocopherols are repackaged into VLDLs (RRR α-tocopherol preferentially included) --> sent out to adipose tissue and cell membranes --> stored throughout body, but mostly in liver, adipose tissue, and plasma

Back

In what forms is vitamin E ingested? Which has the highest activity? What are the other forms important for?

Front

8 naturally occurring forms of tocopherol isolated from plants (4 tocopherols and 4 tocotrienols) alpha, beta, gamma, delta 1) α-tocopherol has the widest natural distribution and greatest physiologic activity 2) beta, gamma, and delta-tocopherols are also of dietary significance 3) delta, gamma forms are used as natural preservatives in pet foods

Back

In what forms is vitamin E used in the body?

Front

RRR-α-tocopherol- has the greatest biological activity of all tocopherols

Back

What is "natural" alpha-tocopherol?

Front

Tocopherol mixtures isolated from plants that are often methylated

Back

What are the best dietary sources of vitamin E?

Front

plants, liver, animal fat

Back

What is glutathione? What three amino acids are required for its synthesis?

Front

cysteine, glycine, glutamate

Back

From where and how is vitamin E absorbed?

Front

Occurs in the upper and middle third of the SI along with the lipid components of the diet (with bile acids) --> tocopheryl esters (ie. tocopheryl acetate) are hydrolyzed to free tocopherol and incorporated into micelles --> micelle enters the enterocyte and tocopherol is incorporated into chylomicrons --> secreted into lymphatics --> tocopherols may "rub off" onto cells like RBCs

Back

In what form is vitamin E supplied in commercial pet foods?

Front

-Added to pet diets as esters, such as tocopherol acetate (higher recoveries following extrusion and drying and less storage loss) -beta and gamma-tocopherol used as preservatives -synthetic α-tocopherol is a mixture of 8 stereoisomers and has been designated as all-rac (racemic) α-tocopherol

Back

What are the signs of vitamin E toxicity (if any)?

Front

extreme intakes may interfere with absorption or metabolism of Vit D and K (shown in chickens/rats)

Back

Once vitamin E has scavenged a free radical, what form does it take and how is it regenerated?

Front

tocopherol is converted to the tocopherol radical and is regenerated by Vit C, glutathione, +/- ubiquinone

Back

What conditions (if any) inactivate vitamin E?

Front

high rate of loss in storage

Back

What are the signs of vitamin E deficiency in dogs?

Front

**muscular degeneration due to influx of Ca++ (white muscle disease), repro failure in males/females, retinal degeneration, SC edema, anorexia, depression, eventual coma (note that these signs are similar to Vitamin A except the muscular degeneration)

Back

What vitamin protects against oxidative destruction of vitamin E?

Front

vitamin C

Back

What effect can high doses of vitamin E have in older dogs?

Front

improved immune function

Back

How is vitamin E excreted?

Front

via bile and excretion in the feces

Back

What are the signs of vitamin E deficiency in cats?

Front

*Steatitis (looks like abdominal pain), *nodular adipose tissue (accumulation of lipofuscin), depression, anorexia

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