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Flashcards in 18 phytosterols Deck (29):
1

Phytosterols are structually similar to?

cholesterol

2

What are phytosterols

plant derived sterols
- similar to cholesterol
- not synthesized by humans

3

Phytosterols can be subdivided into?

sterols
- double bond at position 5

stanols
- reduced double bond
- less in food
- product of intestinal degradation of sterols

4

Atherogenic

tending to promote the formation of fatty plaques in arteries
- Phytosterols and Cholesterol

5

Difference between phytosterols and cholesterol

Phytosterols
- plant
- 1-15% absorbed (helps its function)
- blood levels 200times less

6

Highest food sources of phytosterols

nuts
seeds
legumes
vegetable oils
- processing influences content
- hydrogenation DOESNT influence content

7

Cholesterol lowering effects of phytosterols apparent in what amount?

low gram amounts

8

Phytosterols 3 areas of focus on health

1. CVD**(most attention)
2. Cancer
3. Immune Health

*supplement form*

9

Phytosterols and CVD

lowers blood lipids (2gram sterol/stanols per day)
- total and LDL
- no effect HDL cholesterol of TG

*note - no direct link to heart disease yet

10

Phytosterols mechanism for reducing total and LDL-cholesterol?

- compete with cholesterol for limited space on mixed micelles in the intestine
- more hydrophobic - therefore greater affinity
- decreases cholesterol absorption 30-50%
- dietary and endogenous chol.

11

Types of cholesterol phytosterols compete with?

dietary chol. (20%)
endogenous chol. (80%)
- biliary chol, secreted in bile

12

where does unabsorbed cholesterol go?

feces

13

Does form of phytosterols influence efficacy?

ALL EFFECTIVE
plant sterol/stanol esters
free sterol/stanol

14

Study on CVD; phytosterols vs drugs

American Journal of Cardiology 2002
- cervistatin and sterol-ester margarine together
- possible synergistic effect
- result additive effect

sterols added further benefit to drug (lower cholesterol in different ways)

15

why phytosterols hard to incorporate in foods?
how to overcome this?

low fat solubility
- esterfied with fatty acid to increase solubility

* esterfied gram amounts higher than sterol itself (overestimated)
1g sterol/stanol
.6g FAs

16

USA recommendation of phytosterols for CHD

2 servings of foods
- 2-3grams

17

Typical foods phytosterols are incorpertated in?

Fatty foods
- margarine, salad dressing, yoghurt, cream cheese

-Benecol Softgels (supplement)
-Take Control (supplement)

18

Why are phytosterol functional foods NOT in canada?

Benecol (softgels)
- caused many problems when labelling regulations were limited

19

Phytosterols and cancer

prostate cancer
- inhibited cancer cell growth in vitro
-improved symptoms associated with benign prostate hyperplasia in humans

colon cancer
-inhibit colon cell proliferation
-inhibit proliferation of cancer cells (in vitro)

20

Potential mechanisms of action of phytosterols on cancer

membrane
- structure
- fluidity
- integrity
- bound enzymes
signal transduction
apoptosis
effects on neutral and acidic sterols in the colon

21

What is a glucoside

a glycoside derived from glucose
- a molecule which sugar is bound to another functional group

22

What phytosterols are shown to be immune modulators?

Beta-sitosterol (BSS)
and its glucoside (BSSG)

23

Phytosterols relation to immunity

BSS and BSSG
In VItro:
- increase proliferation of lymphocytes
- anti-inflammatory

In humans:
- recovery tuberculosis
- improvement HIV
- rheumatoid arthritis

24

Phytosterol safety issues?

Decreased absorption of fat soluble nutrients (acute)
- timing
- consumed with phytosterols

25

Fat soluble nutrients affected / not affected when consumed with phytosterols

decreased plasma carotenoids
- beta carotenoids 25%
- alpha carotenoids 10%
decrease lycopene

Vitamin A, D, E and K NOT affected
-carotenoids carried by LDL but Vit A is not

>1 serving of veggies will maintain satisfactory levels

26

Phytosterolemia

- error in phytosterol metabolism
- intestinal inability to distinguish between phytosterol and cholesterol
- no sterol excretion in bile

Result:
-premature atherosclerosis
-Extremely high conc. of phytosterols

VERY RARE (40 worldwide)

27

Cholesterol 7alpha-hydroxylase

rate limiting step in bile acid synthesis
- inhibited by sitosterol during phytosterolemia

28

Max free phytosterol amount allowed in food per serving?

1g per serving
- effects believed to plateau >3g

29

Meaning of "specific composition criteria"

ex. phytosterols
-must be in product with low saturated fat
- can't claim lowers cholesterol when contains other substances that will raise cholesterol