Lignans and Resveratrol

Question 1

Lignans

Answer 1

Lignans can be metabolised by intestinal bacteria to form the phytoestrogen compounds enterodiol and enterolactone:
* They are said to be the ‘Western equivalent’ of phytoestrogens and are a soy alternative.
* It is thought that variations in the intestinal bacteria mean that in Western populations tend to tolerate lignans more than soy.

Question 2

Lignans: Food Sources

Answer 2

• Flaxseeds (most abundant 1 oz, 85.5mg)
• Sesame seeds (1 oz, 11.2mg), beans and pulses, cruciferous vegetables.

Question 3

Lignans: Function

Answer 3

Oestrogen Modulation
Anti-cancer

Question 4

Lignans: Oestrogen modulation

Answer 4

• Bind to oestrogen receptors exerting an oestrogenic
  effect that is milder than endogenous oestrogens.
• Where oestrogen levels are low the net effect is
  to ↑ oestrogenic activity
• Where oestrogen levels are high, lignans
  antagonise endogenous oestrogens.

Question 5

Lignans: Oestrogen modulation - Therapeutic Uses

Answer 5

• Menstrual irregularities Dosage: 2 tbsp whole
  flaxseed per day (i.e. seed cycling)
• Menopause support ↓ frequency and intensity of hot flushes; improves vaginal atrophy and cognitive function; supporting bone density, ↓ osteoporosis risk.
  Dosage: 2 tbsp flax per day.

Question 6

Lignans: Anti-cancer

Answer 6

• Lignans anti-cancer properties especially in hormonally driven breast and prostate cancer. There is also evidence for a role in endometrial and ovarian cancer.
• The following anti-cancer mechanisms have been found:
  – Modulation of oestrogen metabolism and receptor
  signalling pathways leading to decreased cell proliferation and angiogenesis.
  – Strong anti oxidant properties.
  – Reduces 5α reductase activity, thereby reducing the more biologically potent DHT (prostate).
• Dosage: 25 g / day (providing 50 mg lignans).

Question 7

Lignans: Intake and dosage

Answer 7

• Consume 25g flaxseed (approximately 50 mg lignans) daily.
• Lignans are not associated with the oil fraction of foods so intake of whole flaxseeds (ground) are needed to obtain benefits.
• Flaxseeds contain polyunsaturated fatty acids that are unstable and oxidise readily if exposed to oxygen, light and heat (avoid cooking use to garnish).
• Best consumed from flaxseeds that are freshly
  ground . Ground flaxseeds also oxidise easily so do not purchase them ground.

Question 8

Lignans: Safety

Answer 8

• Lignan precursors in foods are not known to have any adverse effects.
• Flaxseed may lower blood glucose levels and might have additive effects when used with anti diabetic drugs
• The safety of lignan supplements in pregnant
  or lactating women has not been established.

Question 9

Resveratrol

Answer 9

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

Question 10

Resveratrol: Food Sources

Answer 10

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

Question 11

Resveratrol: Functions

Answer 11

Anti-oxidant
Insulin sensitivity
Oestrogen modulation

Question 12

Resveratrol: Anti-oxidant

Answer 12

It is a potent antioxidant that can:
* Prevent LDL oxidation.
* Support fertility (e.g. sperm
* Provide anti cancer properties (also suppresses cell proliferation(

Question 13

Resveratrol: Anti-oxidant - Therapeutic uses

Answer 13

• Cardiovascular health.
• Anti ageing / skin health / fertility.
• Diabetic neuropathy

Question 14

Resveratrol: Insulin sensitivity

Answer 14

• It can improve insulin sensitivity especially in those with obesity. It also reduces fat accumulation.

Question 15

Resveratrol: Insulin sensitivity - Therapeutic uses

Answer 15

• Type 2 diabetes
  Dosage: 150 mg / day

Question 16

Resveratrol: Oestrogen modulation

Answer 16

• A ‘phytoestrogen’. It can inhibit aromatase (reducing testosterone to oestrogen conversation).

Used in:
*
Oestrogen dominance (e.g. breast cancer(

Question 17

Resveratrol: Dosage

Answer 17

• 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 18

Resveratrol: Safety

Answer 18

• 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 ofresveratrol red grape juice is just as rich a source!

Question 19

Resveratrol: Interactions

Answer 19

• 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)