Phytosterols, Carotenoids

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 have a double bond in the sterol ring.
The most abundant sterols in plants and the human
diet are β-sitosterol, campesterol and stigmasterol.
2. 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 2

Phytosterols: Food sources

Answer 2

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

Wheat germ: ½ cup (57 g), 197mg
Sesame oil: 1 tbsp (14 g), 118mg
Pistachios: 1 ounce (28 g), 79mg

Question 3

Phytosterols: Functions

Answer 3

Promotes healthy serum cholesterol
Anti-cancer
Prostate health
Immune health

Question 4

Phytosterols: Promotes healthy serum cholesterol

Answer 4

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

Question 5

Phytosterols: Anti-cancer

Answer 5

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

Question 6

Phytosterols: Prostate health

Answer 6

• 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.

Question 7

Phytosterols: Prostate health - Therapeutic uses

Answer 7

• Benign Prostatic Hyperplasia ( BPH)
• Prostatitis.
• Frequent nocturnal urination in males.

Question 8

Phytosterols: Immune health

Answer 8

• 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.#

Uses: Conditions associated with Th2 dominance
e.g. allergy, asthma.

Question 9

Phytosterols: Safety

Answer 9

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

Question 10

Phytosterols: Interactions

Answer 10

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