Phytonutrients - Phytosterols

Question 1

Phytosterols

Answer 1

• Phytosterols are plant-derived lipids that are structurally similar to cholesterol. The two classes of nutritional significance are:
  1. Sterols
  2. Stanols
  phyto-= plant, sterols = lipids (similar to cholesterol)

Question 2

Sterols

Answer 2

• Sterols —have a double bond in the sterol ring. The most abundant sterols in plants and the human diet are β-sitosterol, campesterol and stigmasterol.

Question 3

Stanols

Answer 3

• Stanols —which lack a double bond in the sterol ring. Stanols are also present in plants, but only comprise about 10% of total dietary phytosterols.

Question 4

Food sources:

Answer 4

• Unrefined vegetable oils, nuts, seeds, whole grains and legumes.

Question 5

Phytosterols Food Table:

Answer 5

Food: Serving: Phytosterols (mg):
Wheat germ: ½ cup (57 g) 197
Sesame oil: 1 tbsp (14 g) 118
Pistachios: 1 ounce (28 g) 79
Almonds: 1 ounce (28 g) 39
Brussels sprouts: ½ cup (78 g) 34
Rye bread: 1 cup (160 g) 33
Macadamia nuts: 1 ounce (28 g) 33
Avocado: ¼ fruit 32
Olive oil: 1 tbsp (14 g) 22

Question 6

Functions and Therapeutic uses:

Answer 6

• Promotes healthy serum cholesterol
• Anti-cancer
• Prostate health
• Immune health

Question 7

Promotes healthy serum cholesterol:

Answer 7

Therapeutic uses: Well documented to lower LDL-cholesterol by:
* Displacing dietary cholesterol from micelles decreasing absorption.
* Disrupting incorporation of cholesterol into chylomicrons impeding transport from enterocytes to the circulation.
* Increasing intestinal clearance of cholesterol.
* Dosage: 2 g / day
Micelles=spheres of lipids, Chylomicrons= transport dietary lipids from the intestines

Question 8

Anti-cancer:

Answer 8

Therapeutic uses:
* Diets rich in phytosterols are associated with reduced risk of cancer.
* Mechanisms supported by experimental research include:
o Inhibiting cell proliferation
o Inducing cell cycle arrest and apoptosis
o Reducing angiogenesis
* Possible anti-tumour effects by enhancing immune surveillance and detection of cancer cells.

Question 9

Prostate health:

Answer 9

Functions:
* Beta-sitosterol (60‒130 mg / day) has shown to improve urinary symptoms and ↑ urinary flow in patients with BPH.
* Inhibits 5-alpha-reductase and aromatase, reducing the formation of dihydrotestosterone and oestradiol which stimulate prostate growth.
Therapeutic uses:
* Benign Prostatic Hyperplasia (BPH).
* Prostatitis.
* Frequent nocturnal urination in males.

Question 10

Immune health:

Answer 10

Functions:
* Plays a role in immune modulation, increasing T-helper 1 (Th1) cell activity.
* May help to re-establish balance where the immune response is Th2 dominant.
Therapeutic uses:
* Conditions associated with Th2 dominance e.g. allergy, asthma.

Question 11

Safety:

Answer 11

• Generally well tolerated. Occasional GI side effects at high doses.
• Safety of high doses (supplements) in pregnancy and lactation has not been established.

Question 12

Interactions:

Answer 12

• Additive effects with cholesterol-lowering medication (statins).
• Higher amounts may reduce absorption of dietary carotenoids.

Question 13

Ashwagandha:

Answer 13

Herbal medicine example:
* The herb Ashwagandha contains phytosterols called with anolides—these exhibit anti-tumour and hepatoprotective effects.