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MY BIOCHEMICAL NUTRITION > Unit 8: Micronutrients – Fat-soluble Vitamins > Flashcards

Unit 8: Micronutrients – Fat-soluble Vitamins Flashcards

1
Q

Definition of vitamin

  1. Organic nutrients found in food
    The distinguishing feature of the vitamins is that they
    generally cannot be _______ by mammalian cells and,
    therefore, must be supplied in the diet.
  2. Perform specific function in the body. Many are ______________
  3. Small daily requirement, ingested frequently
A

synthesized

coenzymes

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2
Q

Definition of vitamin

  1. _____ _______ leads to specific disease, which can
    be cured only by that vitamin
  2. Can exist in multiple forms: pro-vitamin, vitamin and
    (often) coenzyme. The most prominent function is as cofactors for enzymatic reactions.
  3. Can have different _______ __________:
    e.g. Vitamin A: retinol, retinyl ester, retinal, retinoic
    acid
A

Inadequate intake

chemical structures

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3
Q

What vitamins are endogenous?

• Humans can make one fat-soluble vitamin:
– Vitamin ____

• Humans can make one water-soluble vitamin:
– ____________

A

D3

Niacin (Vit B3)

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4
Q

What vitamins are endogenous?

• Human intestinal bacteria make one fat-soluble:
– ____________

• Human intestinal bacteria make one water-soluble:
– __________

A

Vitamin K

Biotin (Vit B7)

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5
Q

Vitamin A

_________ (animal sources) and
____________ (plant sources)
synthesis of sex, adrenal and thyroid hormones

Retinol Activity Equivalent
– One RAE: amount of potency = \_\_\_\_\_
• Equivalent to 1 μg retinol; 
• 12 μg β-carotene, 
• 24 μg α-carotene

RDA:
– Adult male: 900 RAE (________ IU)
– Adult female: 700 RAE (2330 IU)

UL: 3000 RAE (__________ IU)

Vitamin A _______= Retinol, Retinal, Retinyl ester, Retinoic acid

A

Retinol

carotenoids

3.33 IU

3000

10,000

vitamers

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6
Q

Vitamin A–β-Carotene

The breakdown of β-carotene occurs in the walls of the ____ _______ and is catalyzed by the enzyme β-carotene __________
– The retinol is stored in the liver as ____ ____. (This is why cod liver oil used to be taken as a vitamin A supplement).

A

small intestine

dioxygenase

retinyl esters

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7
Q

Vitamin A vitamers: Retinal

1–Retinol is converted in the retina to 11-cis retinal =Transduces light into neural signals for ______

A

vision.

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8
Q

Vitamin A vitamers: Retinoic acid

1–The normal _________ of the cells of the cornea
and conjunctiva is dependent on retinoic acid.

• Retinoic acid acts as a ________ and is involved in signal transduction, mediated by retinoic acid receptors

A

differentiation

hormone

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9
Q

Vitamin A vitamers: Retinyl esters

1–All-trans-retinol occurs naturally in the form of fatty acid esters,
2–Retinyl palmitate and retinyl _____ are the principal
forms used as nutritional supplements.
3–Primary vitamer in _____: Retinyl ester
– Excellent sources: Liver, fish, dairy, eggs

A

acetate

food

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10
Q

Vitamin A–Absorption, Transport and Storage

1—Vitamin A and carotenoids are absorbed in the
________ __________
– Bound to chylomicrons
– Transport via lymph
– Pro-vitamin A carotenoids converted to vitamin A in
the intestinal mucosa or liver.
2—______ is the primary site of storage.
– Others are kidney, adipose and adrenal glands
– Excessive intake of β-carotene causes yellowish skin
due to deposit in subcutaneous adipose tissue
3–– Carotenoids are bound to lipoproteins, such as VLDL
and LDL, for _______

A

small intestine

Liver

transport

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11
Q

Vitamin A: Deficiency

Cause:
– Primary:
• Insufficient intake, usually associated with Protein Energy Malnutrition (PEM) or lack of fruits and vegetables

– Secondary:
• Disorders of _________
• Failure to ________ stored vitamin A (due to liver disease)
• Metabolic defects in converting carotenoids to retinol

–Blindness in the developing world, Night blindness
–Epithelial disorders
–Failures in systemic functions
—Increased risk for infection
–Dry, fissured skin
• Brittle nails
• Hair loss (alopecia)

Toxicity seen with daily supplementation of _______ IU

A

absorption

mobilize

25,000

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12
Q

Vitamin D–Aka: Anti-rachitic factor

Production in skin when exposed to UV irradiation
• Absorption, transport, and storage
• Functions as a steroid hormone
• Maintains calcium and phosphorus homeostasis

RDA
• FNB dietary reference intakes for vitamin D:
– ___ μg for those aged 1–70 years (600 IU);
– ___ μg for those aged 71+ years (800 IU);
– Pregnant / Lactating: 15 μg (600 IU)
– UL: ____ μg (4000 IU)

A

15

20

100

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13
Q

Vitamin D

1–Ergosterol  Pre-D2  Ergocalciferol (vit D2)
– Occurs in yeast and some plants
– Ergo: fungus/mushrooms
2—7-dehydrocholesterol  Pre-D3  Cholecalciferol (vit D3)
– Occurs in human subcutaneous tissue
– Made from cholesterol
3—Humans can make only one fat soluble vitamin:
_________

A

Vitamin D3

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14
Q

Vitamin D–Absorption, Transport and Storage

1–Like all fat-soluble vitamins, Vitamin D is absorbed in the small intestine, bound to _______, and transported through the lymph.

2– Endogenously synthesized vitamin D is bound to ___________ (plasma protein) for transport

A

chylomicrons

α-2-globulin

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15
Q

Vitamin D–Absorption, Transport and Storage

3—Vitamin D is primarily stored in the liver. There is some in the brain, bone and skin. Excessive vit D is excreted in
_____

4— Mobilization of vitamin D, and conversion to its active
form, occurs only when needed and is under ______
regulation

5–Vitamins D2 and D3 are stored in the liver as
____________________

A

bile

hormonal

25-hydroxy-(chole/ergo)calciferol

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16
Q

VITAMIN D–Function of 1,25(OH)2 D3 (Calcitriol)

To maintain ___ _______ at optimal levels (~5 mM or
10 mg/dL)

Major functions of calcium:
1–for use in nerves and muscle
2–mineralization of bones and teeth
3• Regulates insulin secretion / sensitivity
4• Controls cell differentiation and suppresses malignancy
5• Assist immune function
6• Decrease systolic hypertension

A

serum calcium

17
Q

VITAMIN D–Function of 1,25(OH)2 D3 (Calcitriol)

1–Bone: Low serum calcium triggers___ release
2–Self-regulation: (negative feedback): High 1,25(OH)2D3
stimulates ____________ to make more active 24,25(OH)2D, instead of 1,25(OH)2D3
.

A

PTH
***Parathyroid hormone (PTH)– Released when serum calcium is LOW. –OVERALL: PTH INCREASES serum Ca2+ to optimum levels for functions other than bone mineralization

24-hydroxylase

18
Q

Regulation of Vitamin D by calcitonin–Calcitonin (from thyroid)– Released when serum calcium is ________

OVERALL: CALCITONIN will REDUCE serum Ca2+ to optimum levels

A

high

19
Q

Vitamin D: Deficiency

Primary Causes:
– Lack of vitamin D in vegetarian diets, lack of sun exposure (seasonal rickets occur in cold climate)

Secondary causes:
Diseases of intestine, liver or ________

Vitamin D resistant rickets: Chronic use of ______
lowering drugs or barbiturates reduce vitamin D absorption

  • -Rickets in children
  • -Osteomalacia in adults –Osteoporosis
A

kidney

cholesterol

20
Q

Signs of Vitamin D Toxicity

  • Excessive _________ of bones
  • Kidney stones
  • __________ calcification of soft tissue (kidney, heart, lung, and tympanic membrane)
  • Hypercalcemia
A

calcification

Metastatic

21
Q 
Vitamin E--Tocopherols and Tocotrienols
Natural vitamin E has 8 vitamers:
– 4 tocopherols and 4 tocotrienols
– All are ‘d-form’ 
– Their potency (in order)
• Alpha
A

d-α-tocopherol

1

22
Q

Food sources of vitamin E

Sources- Vegetable oils: safflower, sunflower, soybean, Grains: Wheat germ, seeds, cereals and grains, Fortified food: margarine, Dairy: Whole milk (in the fat), Meat / Fish: liver

A

KNOW

23
Q

Functions of vitamin E

__________: neutralizes reactive oxygen species (free radicals). Preserves membrane integrity, and fat soluble factors & Vitamin A, CoQ,
–cytochrome P-450–Detoxifying enzyme in the liver
–malondialdehyde–PUFA that, when oxidized, binds
DNA/RNA/protein/lipid. Therefore a carcinogen.
– Enters a variety of tissue types, found primarily in
__________
• It is thought to play a role there in either stabilizing
CoQ (ubiquinone), or in helping CoQ transfer electrons.
– Plays an important role in protecting ____ against oxidative stress

A

Antioxidant

mitochondria.

RBCs

24
Q

Vitamin E—Absorption, Transport and Storage

Absorption – Like other fat-soluble vitamins,
• it is passively absorbed in the small intestine
• transported by chylomicron, via lymph to the liver

Transport from the liver
1– packaged into HDLs, LDLs, and VLDLs released into the bloodstream.

2– Note: α-tocopherol is selectively incorporated into VLDL, due to its high affinity for α-TTP (α-tocopherol transfer protein), accounting for its high biological activity.

3– In the blood, it prevents the oxidation of ____, a factor in atherogenesis, so adequate amounts of vitamin E _______ against hardening of the arteries, heart attacks, and stroke.

A

LDL

protects

25
Q

vitamin E—Absorption, Transport and Storage

Vitamin E is primarily stored in _____ ________
• Other sites are liver, adrenal glands, ovary/testes and
muscle
– Mobilized from storage sites and transported by LDL,
HDL and VLDL.

A

adipose tissue

26
Q

vitamin E—Absorption, Transport and Storage

1–Tissue Uptake
– By ________ digesting the lipoprotein constituents
EX. Triglycerides, phospholipids, cholesteryl esters, free cholesterol
2–By “_____ _____ _____” : binding of the lipoprotein to a specific tissue receptor site.
EX. Apo-E Receptor
3–– The vitamin can be stored in tissue for years due to its exceedingly slow turnover rate.
4-– Interestingly, the natural __________ form of the vitamin is stored up to six times longer than synthetic versions.

A

lipases

receptor mediated uptake

α-tocopherol

27
Q 
RDA OF VITAMIN E
• α-tocopheral equivalent
– 1 α-TE = 1 mg α-tocopheral = 1.5 IU
• AI for newborns: 4 α-TE (6 IU)
• RDA for adults: 15 α-TE (22.5 IU)
• RDA for pregnancy / lactation: 19 α-TE
• UL for adults: 1000 α-TE (1500 IU)
• 1IU=0.67mg natural=0.45mg synthetic
A

KNOW

28
Q

Vitamin E: Deficiency
1– Hemolytic anemia-abnormal breakdown on ________
2– Increased risk of __________ and certain cancers (due to antioxidant effects)

A

RBCs

atherosclerosis

29
Q

Vitamin E: Excess

1–• GI disturbances: nausea, diarrhea
2-• Vitamin E competes with the other fat-soluble vitamins
A– Prolonged _____ _____ (anti vitamin K)
B– May compete with vitamin A and D and increase their
need in the body
C– In combination with aspirin, hypervitaminosis E can be
life threatening. And counteract vitamin K, leading to a
vitamin K deficiency.

A

bleeding time

30
Q

Vitamin K

Vitamers
1–K1: phylloquinone, phytonadione – SOURCE = green veggies

2–K2: menaquinone, fernoquinone –SOURCE = fermented foods–(cheese/yogurt). Also from bacteria
(_______ _______) Synthesize ~50% of our daily needs

3–K3: menadione = ______ __________

A

intestinal flora

Synthetic drug

31
Q

Vitamin K–Absorption, Transport & Storage

1–Dietary vitamin K is absorbed in the ____ intestine
2–Endogenous vitamin K is absorbed in the____intestine
3– Bound to chylomicrons
4– Transported through lymph

A

small

large

32
Q

Vitamin K–Absorption, Transport & Storage

5–Excessive intakes of ____ impairs vitamin K
absorption!
6– Storage of vitamin K in the body is relatively ___. Perhaps due to continuous supply by the intestinal
bacteria.
7– Major storage is in ______
8– Other sites: skin, muscle, kidney and heart

A

Ca2+

low

liver

33
Q

Vitamin K: Function
• Vitamin K is a coenzyme for γ-glutamic
carboxylase, and is therefore required for:
– ________ __________…but
– Prevents excessive blood coagulation
– Stimulates mineralization of bone and teeth
– Maintains serum calcium levels

A

Blood coagulation

34
Q

Vitamin K regulates the “_______ __________”

A

Coagulation Cascade

35
Q 
AI
• AI for newborns: 2.0 μg / day
• AI for adult males: 120 μg / day
• AI for women: 90 μg / day
– (including pregnancy & lactation):
• UL for adults: \_\_\_\_\_\_\_\_
A

Unknown

36
Q

Vitamin K: Deficiency

Symptoms:
1–Impaired blood ________ (anemia and prolonged bleeding)
2–Muscular and subcutaneous _______
3–Impaired mineralization of bone and teeth (hip fractures)

A

coagulation

hemorrhage

37
Q

Vitamin K: Excess

• Mostly due to K3 administration

Symptoms:
– Increased hemolysis and hyperbilirubinemia in _____
– Hypotension
– Weakness due to vitamin K interference of ___ of
the respiratory chain

A

infants

CoQ

38
Q

Practical Issues: Nutrient-nutrient interactions

  • Lipid foods increase fat-soluble vitamin absorption
  • Vitamin A increases the number of receptors for 1,25(OH)2D, and enhances the action of vitamin D
  • Adequate intake of ____&_______ are essential for the mobilization of stored Vitamin A
A

protein and Zinc

39
Q

Practical Issues: Nutrient-nutrient interactions

• Mineralization of bone and teeth requires the simultaneous adequate intake of Vitamins A and D, Ca, P, Mg, Cl
• Vitamin E and Se are both _________ and enhance each other’s activity; they also spare vitamin A. However,
excessive intake of vitamin E antagonizes vitamins A, D, and K.

A

anti-oxidants

MY BIOCHEMICAL NUTRITION (9 decks)

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