Fat soluble vitamins

Question 1

What are the two dietary forms of Vitamin A? What are the food sources of each?

Answer 1

Pre-formed as retinyl esters or retinol, and provitamin carotenoids.

Retinol esters and retinol are found in animal products.

Carotenoids are found in vegetables and vegetable products and fortified foods.

Question 2

How many types of provitamin A are there?

Answer 2

3

Question 3

How many molecules of vitamin A are gained by cleavage of a provitamin A?

Answer 3

2

Question 4

What is beta-cryptoxantin?

Answer 4

A precursor to vitamin A that generates one molecule of vitamin A upon cleavage.

Question 5

What is the difference between central and eccentric cleavage of provitamin A compounds?

Answer 5

Central cleavage generates two vitamin A molecules and eccentric cleavage generates other molecules.

Question 6

What are the dietary sources of vitamin A?

Answer 6

Meat, poultry, fish, liver, eggs, dairy (only occurs naturally in milk with fat)

Question 7

What are the dietary sources of carotenoids?

Answer 7

Green leafy veggies, bright veggies, veggie oil, eggs.

Question 8

Name five biological roles of vitamin A.

Answer 8

Vision, cell division and differentiation, reproduction, immune function, bone growth.

Question 9

Are carotenoids antioxidants?

Answer 9

Yeah

Question 10

In which organ is vitamin A stored?

Answer 10

Liver

Question 11

How is vitamin A transported throughout the body?

Answer 11

On retinol binding protein (RBP)

Question 12

Where in the body are carotenoids stored? What are they transported on?

Answer 12

Stored in liver and adipose tissue. Transported on lipoproteins.

Question 13

Is vitamin A deficiency common in the U.S.?

Answer 13

Nope

Question 14

What disorders can inhibit the absorption of fat-soluble vitamins?

Answer 14

Pancreatic insufficiency (lipase or colipase insufficiency), bile production disorders such as duct blockage.

Anything that messes with fat absorption.

Question 15

What are the symptoms of Vitamin A deficiency (12 of them)?

Answer 15

Decreased night vision, increased keratinization of epithelium, xeropthamia (dry eyes), Bitot’s spots on eyes, impaired wound healing, increased infection risk, Measles risk, respiratory infections, diarrhea, increased fetal death, decreased spermatogenesis, stunting due to decreased bone growth.

Question 16

What role does the kidney play in Vitamin A metabolism?

Answer 16

It clears retinol binding protein. If there is kidney disease then RBP cannot be cleared, leading to a build up of Vitamin A.

Question 17

Is vitamin A toxicity usually due to supplementation?

Answer 17

Yeah.

Question 18

What are the manifestations of vitamin A toxicity (10)?

Answer 18

Weight loss/anorexia, liver damage and cirrhosis, hair loss, dry mucous membranes, lips, and skin, headache, bone and joint pain, osteoporosis and fractures due to increased osteoclast activity, hypercalcemia, bleeding, teratogenicity.

Question 19

How is provitamin A cleavage regulated?

Answer 19

Through TFs and expression of enzymes that cleave eccentrically or centrally. If enough vitamin A is present in body, eccentric cleavage will dominate. That’s why its hard to become toxic with food ingestion.

Question 20

What physical exam finding is indicative of hypercarotenemia vs. jaundice?

Answer 20

Peeps with jaundice will have yellow eyes, too.

Question 21

A study on beta-carotene supplementation in smokers showed an increase in ___________.

Answer 21

lung cancer rates

Question 22

How can vitamin A status be assessed (6 ways)?

Answer 22

Serum retinol, RBP, or carotenoids. Night vision testing, liver function and bone mineral content.

Question 23

What are the food sources of Vitamin D2 (ergocalciferol)?

Answer 23

Plants, fungi, invertebrates, supplements.

Question 24

What are the food sources of Vitamin D3 (cholecalciferol)?

Answer 24

Animal foods, fortified foods, milk, orange juice, supplements.

Question 25

Which organs are involved in Vitamin D synthesis and what are their respective products?

Answer 25

Skin makes D3, liver makes 25-hydroxycholecalciferol, kidney makes 1,25-hydroxycholecalciferol (most active form of vitamin D)

Question 26

PTH stimulates vitamin D hydroxylation in the ______ to increase intestinal absorption and it also ________ osteoclast activity.

Answer 26

kidney, increases

Question 27

What are the biological roles of vitamin D?

Answer 27

Calcium and phosphorus homeostasis and absorption, bone health, muscle function.

Question 28

Who is at risk for vitamin D deficiency?

Answer 28

Older peeps due to decreased skin synthesis, people with limited sun exposure, peeps with dark skin.

Dietary risks: breast-fed infants, lactose intolerant folks, obese peeps, peeps with end-stage liver or kidney disease, people on corticosteroids or anticonvulsants.

Question 29

What are the manifestations of vitamin D deficiency?

Answer 29

Rickets in children, osteomalacia —-> osteoporosis in adults.

Question 30

What is the primary cause for vitamin D toxicity? How does it manifest (7 symptoms)?

Answer 30

Overuse of supplements. Results in hypercalcemia, anorexia, nausea, vomiting, calciuria, kidney stones, arrhythmia.

Question 31

How can one assess vitamin D status?

Answer 31

Serum 25-OH, PTH, serum calcium, DEXA

1,25-OH does NOT! It is not decreased until severe deficiency.

Question 32

What are the food sources of vitamin E?

Answer 32

Nuts, seeds, veggie oil, wheat germ, green leafy veggies, olives, fortified foods, supplements.

Question 33

What are the biological roles of vitamin E (name 4)?

Answer 33

Antioxidant: prevents RBC hemolysis and lipid peroxidation, immune function, DNA repair

Question 34

Have studies shown that vitamin E supplementation may prevent cancer, cardiovascular disease and dementia?

Answer 34

No consistent evidence.

Question 35

Who is at risk for vitamin E deficiency?

Answer 35

Premature babies, people with alpha-tocopherol transfer protein deficits, people with abetalipoproteinemia.

Question 36

How is vitamin E status assessed?

Answer 36

Serum vitamin E levels

Question 37

What are the manifestations of vitamin E deficiency (5)?

Answer 37

Peripheral neuropathy, myopathy, retinopathy, immune dysfunction, RBC hemolysis.

Question 38

Vitamin E toxicity is usually due to what?

Answer 38

Over-supplementation.

Question 39

What are the two dietary forms of vitamin K? Which one is most commonly found in American diets?

Answer 39

Phylloquinone (K1) and menoquinone (K2). K1 most common in U.S.

Question 40

What are the dietary sources of phylloquinone (K1) and menoquinone (K2), respectively?

Answer 40

K1: green leafy veggies, veggie oil, soybeans, fortified foods.
K2: Fermented foods, animal foods, dairy, intestinal bacteria.

Question 41

Where is vitamin K stored in the body?

Answer 41

Liver and adipose

Question 42

What is the biological function of vitamin K?

Answer 42

Cofactor for gamma carboxylation of proteins with Vitamin K dependent carboxylase.

Question 43

How can vitamin K status be assessed?

Answer 43

Serum vitamin K reflects recent intake. PT/INR will be elevated in severe deficiency. Vitamin K epoxide is measured for research purposes.

Question 44

Who is at risk for vitamin K deficiency?

Answer 44

Babies are always born deficient and SOC is to supplement at birth. Peeps with malabsorptive diseases, liver disease, and alcoholics at risk.

Question 45

What symptoms result from vitamin K deficiency?

Answer 45

Bleeding.

Question 46

What is warfarin embryopathy?

Answer 46

Due to warfarin use or severe vitamin K deficiency in pregnancy. Results in chrondrodysplasia punctata: impaired calcium scavenger results in bony deformities with excess calcification and nasal hypoplasia, and mental retardation in the baby.

Question 47

What is vitamin K epoxide reductase genotyping done for?

Answer 47

To determine warfarin dosing

Question 48

What does alpha-tocopherol transfer protein do and what are you at risk for if yours is messed up?

Answer 48

It transports vitamin E out of the liver and into the bloodstream, so if its messed up you can be vitamin E deficient.