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Nutrition 3330 > 16 Phytoestrogens > Flashcards

16 Phytoestrogens Flashcards

1
Q

3 main categories of phytoestrogens

A

Isoflavons
lignans
coumestans

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2
Q

Good qualities of a biomarker

A 
Feasibility
Specificity **
Sensitivity **
Invasiveness
Cost 
Validated Reference Ranges
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3
Q

Classic definition of phytoestrogens?

A

Non-steroidal plant compound able to exert estrogenic effects
(naturally occurring)

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4
Q

Phytoestrogens are structurally similar to?

A 
endogenous estrogen (Estradiol)
synthetic E and anti-E
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5
Q

Food sources of isoflavons

A

*soy beans and soy products
legumes
clover

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6
Q

Isoflavones are found in what forms?

A

Glycoside (typical food form)

Aglycone (fermented foods, absorbed in this form)
- carb group removed

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7
Q

3 major isoflavones present in soy?

A

Genistin / Genistein
Daidzin / Daidzein
Glycitin / Gycitein

(60/30/10 proportions)

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8
Q

What is present in clover?

A

isoflavone precursors:

  1. formononetin
    - daidzein
  2. Biochanin A
    - genistein
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9
Q

Formononetin

A

isoflavone precursor of daidzein

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10
Q

Biochanin A

A

Isoflavone Precursor of genistein

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11
Q

Where are isoflavone precursors converted to isoflavones?

A

Intestine

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12
Q

Important concept to consider when estimating isoflavone intakes?

A

Glycoside vs Aglycone form

  • glycoside form has carb group still attached
  • would overestimate intake
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13
Q

Isoflavone Database

A

to increase “accuracy” of intake estimates and relation of intake to disease risk

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14
Q

Key physiological feature that effects isoflavone absorption

A

Intestinal bacteria

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15
Q

what effects intestinal bacteria

A

antibiotics
pro/prebiotics
travel (food consumption)

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16
Q

Foods that would have isoflavone in its aglycone form?

A

fermented foods

- ex. soy sauce

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17
Q

Absorption form of aglycones?

A

aglycone

isoflavone metabolites

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18
Q

Important isoflavone metabolite

A

Equol

  • from daidzein
  • only 30%-40% of population has gene to produced intestinal bacteria for the conversion
  • higher in asia
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19
Q

Equol compared to other isoflavones and isoflavone metabolites?

A
  • potent
  • binds with higher affinity
  • longer half-life
  • inversely associated with breast cancer
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20
Q

Potential health benefits of soy isoflavones?

A 
Cancer (hormone dependent)
CVD
Osteoporosis
Menopausal Symptoms
Cognitive function
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21
Q

Clover disease

A

Red clover - high in formononetin

  • in Australian sheep
  • fertility problems
22
Q

Isoflavone and fertility

A

Studies show effects in animals
BUT no studies in humans
(more studies in females)

23
Q

Estrogenic Potency of Isoflavones

A

potency 1/1000
found in blood 1000x great amounts

(E = pico, iso = nano to low micro amounts)

24
Q

Isoflavones have similar structure to what estrogen?

A

estradiol

25
Q

estrogenic vs anti-estrogenic effect of isoflavone dependent on ?

A

concentration of endogenous estrogen

26
Q

Effect of isoflavone when endogenous estrogen is high

A

Anti-Estrogenic Effect

  • isoflavones compete for estrogen receptors
  • weaker than estrogens
27
Q

Effect of isoflavone when endogenous estrogen is low

A

Estrogenic Effect

- DON’T compete for estrogenic receptors

28
Q

breast cancer inverse relation to isoflavone based on what 3 parameters?

A

Dietary Intake
Urinary excretion
Blood concentration

29
Q

Other than intake and biomarker parameters, what other importance factor relates to breast cancer and isoflavones

A

age of exposure

  • puberty best time
  • both puberty and adult is best
30
Q

relation between rostate cancer and isoflavones?

A

Inverse relation shown but conflicting data in human studies

Animal studies showed reduced risk, and reduction of size in existing tumors

31
Q

Isoflavon mechanisms on cancer reduction?

A
  • Reduced concentration of reproductive hormone
  • antioxidant effects
  • inhibit tyrosine kinase
  • inhibit angiogenesis
  • inhibit DNA topoisomerase
  • induce apoptosis
32
Q

Inhibition of angiogenesis

A

reduced blood flow to cancer cells

33
Q

inhibition of DNA topoisomerase

A

destabalizes cancer cells

34
Q

Soy and CVD

A

Soy “PROTEIN” associated with reduced:

  • total cholesterol
  • LDL-cholesterol
  • triglycerides
  • aortic stiffness

increased:

  • systemic arterial compliance
  • LDL resistance to oxidation
35
Q

Difference in extracted soy isoflavones? what does this mean?

A

No Effects on

  • total cholesterol
  • LDL, HDL
  • Triglycerides

supports need for presence in “soy protein”

36
Q

People at highest risk of osteoporosis? Typical treatment?

A

Postmenopausal women

- hormone replacement therapy

37
Q

Why we originally related isoflavones to osteoporosis

A

Asian women significantly lower hip fractures to white women

38
Q

Soy isoflavone relation (with respect to osteoporosis)?

A

Increase Bone Marrow Density

39
Q

Soy isoflavone used as an alternative to what treatment?

A

Hormone replacement therapy

HRT

40
Q

Problems with studies of isoflavones on menopausal symptoms?

A

HUGE placebo effect

  • seasonally different
  • self reported data (difficult to measure)
41
Q

Graphical representation of soy isoflavone intake and plasma concentrations and bioavailability

A

Curvilinear

  • plateaus
  • saturable
42
Q

Lignin food sources

A
  • high in flaxseed
  • whole grains, fruits, veggies, seeds

more widespread than isoflavones

43
Q

Plant vs Mammalian ligans

A

plant lignans are precursors for mammalian lignans

- only some plant absorbed, most converted to mammalian

44
Q

Plant lignans

A

Secoisolariciresinol (SECO)
Mateaiesinal
- in lignan rich foods

45
Q

Mammalian Lignans

A

Enterodiol
Enterolactone
- in biological fluids

46
Q

What plant lignan makes what mammalian lignans

A

SECO –> Enterodiol

Matairsinol –> Enterolactone

47
Q

Lignin Health Effects

A 
Human data: (very little available)
-Breast cancer
-CVD
Animal Data:
-osteoperosis 
-colon cancer
48
Q

Coumestan food sources

A

sprouts: bean, alfalfa, soybean

clover

49
Q

Main coumestan? Features?

A

Coumestrol

  • similar to estradiol
  • can bind to ERs
50
Q

Pharmakinetics

A

branch of pharmacology dedicated to determine fates of substances admitted to an organism externally (drugs, nutrients, toxins etc)

Nutrition 3330 (22 decks)

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