Phytonutrients - Resveratrol

Question 1

Resveratrol

Answer 1

• Resveratrol is the most studied stilbenoid. It is a powerful antioxidant produced by some plants to protect them against environmental stresses:

Question 2

Food sources:

Answer 2

• Red grapes (skins).
• Blueberries, mulberries, raspberries, cranberries.
• Peanuts with red skins on, pistachios.
• Cocoa.

Question 3

Functions:

Answer 3

• Antioxidant
• Insulin sensitivity
• Oestrogen modulation

Question 4

Antioxidant:

Answer 4

Functions: It is a potent antioxidant that can:
* Prevent LDL oxidation.
* Support fertility (e.g. sperm health).
* Provide anti-cancer properties (also suppresses cell proliferation).
Therapeutic uses:
* Cardiovascular health.
* Anti-ageing / skin health / fertility.
* Diabetic neuropathy

Question 5

Insulin sensitivity:

Answer 5

Functions:
* It can improve insulin sensitivity —especially in those with obesity. It also reduces fat accumulation.
Therapeutic uses:
* Type 2 diabetes
* Dosage: 150 mg / day

Question 6

Oestrogen modulation:

Answer 6

Functions:
* A ‘phytoestrogen’. It can inhibit aromatase (reducing testosterone to oestrogen conversation).
Therapeutic uses:
* Oestrogen dominance (e.g. breast cancer).

Question 7

Dosage:

Answer 7

• Trials looking at the effects of resveratrol in both healthy subjects and those with medical conditions have used dosages ranging from 10 mg–1 g per day.
• Most supplements on the market are derived from Japanese knotweed because this plant has one of the highest concentrations of resveratrol in nature.
• Resveratrol is very expensive so doses above about 100 mg per day will likely be cost prohibitive.
• The concentration of resveratrol in the blood is more bioavailable in the morning (due to diurnal variations in its metabolic pathway).

Question 8

Safety:

Answer 8

• There is currently no evidence that resveratrol can be toxic or cause adverse effects in humans.
• The safety of resveratrol-containing supplements during pregnancy and lactation has not been established.
• Avoid recommending alcohol consumption as a source of resveratrol —red grape juice is just as rich a source!

Question 9

Interactions:

Answer 9

• High intakes of resveratrol (e.g. supplements) could increase the risk of bleeding when taken with anticoagulant drugs
• Resveratrol inhibits the activity of cytochrome P450; thus high intakes of resveratrol (e.g. from supplements) could theoretically increase the bioavailability and toxicity of drugs that undergo extensive first-pass metabolism by CYP450 (statins, immune-suppressants, calcium channel blockers, etc.)