Lignans – the new phyto oestrogen

What are lignans?

Lignans are phyto-nutrients found in a wide variety of foods such as, flaxseed, whole grains, beans, legumes, fruits and vegetables. They are actually the components in these plants that develop into the hard outer tissue, known as lignin tissue. Our intestines convert lignan-rich foods into beneficial hormone-like compounds, phytoestrogens. (This conversion is blocked however, if you take antibiotics or have a high fat diet.) Flaxseed contains 75–800 times more lignans than any other plant.

The most important lignan in flaxseed is secoisolariciresinol diglycoside, but we shall refer to it by its much simpler form, SDG. When eaten, SDG in flaxseed is converted by bacteria in the colonto the mammalian lignans-enterolactone and enterodiol. Thisconversion is crucial as it is only in this form that lignans have beneficial effects for human health.

Lignans are concentrated in the following foods:

Flaxseeds*, peanuts, caraway seeds, lentils, soybeans, kidney beans, barley, rye, oats, broccoli, garlic, carrots, cranberries, strawberries, raspberries, bananas, guavas and cantaloupe.

*Most flaxseed lignans are removed during the processing of seeds to oil, so they are generally not found in any great degree in flaxseed oil.

Benefits of lignans

Studies have confirmed that lignans and lignan-rich foods may have the capacity to:

• beneficially modify oestrogen and testosterone
• reduce hot flushes, sleep disturbances and other menopausal symptoms
• prevent heart disease
• benefit the immune system
• lower the risk of gastrointestinal cancers
• reduce constipation
• benefit bone health
• modify hormone-dependant acne

Recommended therapeutic dose

Although there are not yet any set guidelines for lignan intake, a sensible amount would be to aim for be approximately 50–150mg per day.*

This translates to one tablespoon of flaxseed meal daily (each rounded tablespoon equals 10 grams linseed meal which provides approx 50–150 mg of lignans), plus a diet rich in whole grains particularly barley and rye, legumes – think soybeans, vegetables – emphasize broccoli and carrots, and fruits, particularly strawberries and cranberries. Now thatʼs no hardship! We are fortunate to have a wide and delicious array of naturally occurring lignans available to us all year round. The plant kingdom never lets us down.

*It is important to note however that very few studies have been conducted examining the effect of lignans in pregnant and breastfeeding women, as well as in young children or women being treated for breast, uterine or ovarian cancer. Therefore until further definitive studies are conducted, lignans cannot be recommended for these groups.

Lignan-rich muesli

The grains are best left to soak overnight but even a half hour soak will still provide delicious results.

• 1 cup rolled rye flakes
• 1/2 cup barley flakes
• 1/2 cup rolled oats
• 1 cup linseed meal
• 11/2 cups water
• 2 cups raspberries, blueberries and strawberries
• 1 tablespoon toasted sesame seeds
• Tahini to taste

Soak rye, oats and barley in the water overnight. Add the linseed meal and sesame seeds. Mix raspberries, blueberries and strawberries together. Add to the oats and barley. Drizzle with tahini and serve with soy yoghurt or soy milk.

(This is an edited extract from my article in Nature & Health magazine, May 2006)