18 phytosterols

Question 1

Phytosterols are structually similar to?

Answer 1

cholesterol

Question 2

What are phytosterols

Answer 2

plant derived sterols

• similar to cholesterol
• not synthesized by humans

Question 3

Phytosterols can be subdivided into?

Answer 3

sterols
- double bond at position 5

stanols

• reduced double bond
• less in food
• product of intestinal degradation of sterols

Question 4

Atherogenic

Answer 4

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

Question 5

Difference between phytosterols and cholesterol

Answer 5

Phytosterols

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

Question 6

Highest food sources of phytosterols

Answer 6

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

Question 7

Cholesterol lowering effects of phytosterols apparent in what amount?

Answer 7

low gram amounts

Question 8

Phytosterols 3 areas of focus on health

Answer 8

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

supplement form

Question 9

Phytosterols and CVD

Answer 9

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

Question 10

Phytosterols mechanism for reducing total and LDL-cholesterol?

Answer 10

• 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.

Question 11

Types of cholesterol phytosterols compete with?

Answer 11

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

Question 12

where does unabsorbed cholesterol go?

Answer 12

feces

Question 13

Does form of phytosterols influence efficacy?

Answer 13

ALL EFFECTIVE
plant sterol/stanol esters
free sterol/stanol

Question 14

Study on CVD; phytosterols vs drugs

Answer 14

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)

Question 15

why phytosterols hard to incorporate in foods?

how to overcome this?

Answer 15

low fat solubility
- esterfied with fatty acid to increase solubility

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

Question 16

USA recommendation of phytosterols for CHD

Answer 16

2 servings of foods

- 2-3grams

Question 17

Typical foods phytosterols are incorpertated in?

Answer 17

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

• Benecol Softgels (supplement)
• Take Control (supplement)

Question 18

Why are phytosterol functional foods NOT in canada?

Answer 18

Benecol (softgels)

- caused many problems when labelling regulations were limited

Question 19

Phytosterols and cancer

Answer 19

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)

Question 20

Potential mechanisms of action of phytosterols on cancer

Answer 20

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

Question 21

What is a glucoside

Answer 21

a glycoside derived from glucose

- a molecule which sugar is bound to another functional group

Question 22

What phytosterols are shown to be immune modulators?

Answer 22

Beta-sitosterol (BSS)

and its glucoside (BSSG)

Question 23

Phytosterols relation to immunity

Answer 23

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

In humans:

• recovery tuberculosis
• improvement HIV
• rheumatoid arthritis

Question 24

Phytosterol safety issues?

Answer 24

Decreased absorption of fat soluble nutrients (acute)

• timing
• consumed with phytosterols

Question 25

Fat soluble nutrients affected / not affected when consumed with phytosterols

Answer 25

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

Question 26

Phytosterolemia

Answer 26

• 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)

Question 27

Cholesterol 7alpha-hydroxylase

Answer 27

rate limiting step in bile acid synthesis

- inhibited by sitosterol during phytosterolemia

Question 28

Max free phytosterol amount allowed in food per serving?

Answer 28

1g per serving

- effects believed to plateau >3g

Question 29

Meaning of “specific composition criteria”

Answer 29

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