Flax Lignans – Nature’s Richest Source
An Overview
Lignans are among the most fascinating nutrients found in plants, yet few people have ever heard of them. Flaxseed is by far the richest common dietary source, containing hundreds of times more lignans than most other foods we regularly eat.
Although scientists have only begun to understand them over the past few decades, lignans have almost certainly been part of the human diet for thousands of years. As our diets have become increasingly based on refined grains and less fibrous fruit and vegetables, our intake has fallen dramatically. Many researchers now believe this may have deprived us of compounds that quietly contributed to good health throughout our evolutionary history.
What are lignans?
Lignans are naturally occurring plant compounds found in seeds, whole grains, legumes, vegetables and berries. They are not vitamins, but they are biologically active nutrients that appear to play a variety of protective roles in the body.
Flaxseed contains several different lignans. The most abundant by far is SDG (Secoisolariciresinol Diglucoside), together with smaller amounts of Matairesinol, Pinoresinol and Lariciresinol.
These plant lignans are not the final active compounds. After we eat them, beneficial bacteria in the colon convert them into Enterodiol and Enterolactone, known as the mammalian lignans. These are absorbed into the bloodstream where they can influence many tissues throughout the body.
This means lignans are unique because they depend upon a healthy gut microbiome to unlock their full benefits.
Part of Our Nutritional Heritage
For most of human history people ate diets rich in whole grains, seeds and fibrous wild plants, all of which naturally contained lignans.
Today’s diet is very different. Modern crop varieties have had much of their original fibre bred out of them to be replaced by tenderness and sweetness. Whilst refined flour removes many of the plant compounds found in the outer layers of grains. As a result, the average intake of lignans is far lower than that of our ancestors. In other words, humans evolved to have lignans as part of their diet.
Flaxseed offers a simple way of restoring these valuable compounds.
How Lignans Protect the Body
Research suggests lignans may contribute to health in several different ways.
They have antioxidant properties, helping to neutralise free radicals produced during normal metabolism.
They may help regulate unnecessary inflammation, supporting the body’s normal repair processes.
Once converted by the gut microbiome into enterolactone and enterodiol they also act as very mild phytoestrogens. Rather than behaving like the body’s own oestrogen, they appear to compete with stronger natural oestrogens for receptor sites, helping to moderate excessive hormonal stimulation in certain tissues.
Because these effects are relatively gentle, many researchers believe lignans act more as hormone modulators than hormone replacements.
Cardiovascular Health
Research suggests lignans may contribute to a healthier cardiovascular system by:
- helping to reduce oxidation of LDL cholesterol
- producing modest reductions in LDL cholesterol in some studies
- supporting healthy blood vessel function
- contributing to healthy blood pressure
- reducing inflammatory processes involved in cardiovascular disease
Although the effects seen in human studies are generally modest, together they may contribute to long-term cardiovascular health.
Bone Health
After the menopause, falling oestrogen levels contribute to loss of bone density.
Some research suggests the mild phytoestrogenic activity of lignans may help support normal bone maintenance. While the evidence is still developing, they may become one of several dietary factors that help maintain healthy bones alongside calcium, vitamin D, vitamin K and regular exercise.
Gut and Colon Health
The digestive system is where lignans begin their journey.
Beneficial gut bacteria convert SDG into the active mammalian lignans, meaning the microbiome and lignans work together.
Research suggests lignans may:
- encourage beneficial bacteria such as Bifidobacterium
- support production of beneficial short-chain fatty acids (SCFAs)
- help maintain a balanced gut microbiome
- reduce low-grade inflammation within the bowel
- help support the normal barrier function of the colon
This relationship works both ways. The healthier your gut microbiome, the more efficiently it can convert lignans into their active forms.
Lignans for Ladies
One of the best-studied areas of lignan research concerns women’s health.
Because enterolactone has mild phytoestrogenic activity, it appears to help buffer the effects of stronger natural oestrogens. This may be particularly important in tissues such as the breast and uterus where prolonged exposure to high levels of oestrogen is thought to increase disease risk.
Population studies have associated higher lignan intake with a lower risk of breast cancer, particularly after the menopause, although clinical trials have not yet proved a direct cause-and-effect relationship.
Some women also report improvements in menopausal symptoms, perimenopausal symptoms and premenstrual discomfort, although the scientific evidence remains mixed.
Lignans for Men
Despite the name phytoestrogen, flax lignans are not feminising.
This is probably the commonest misconception surrounding flaxseed.
Human studies have found no evidence that normal flax consumption lowers testosterone, reduces fertility or causes feminising effects.
Quite the opposite. In countries where flax consumption is traditionally high, there is no suggestion that men are any less masculine or fertile.
The reason is simple. Plant phytoestrogens are thousands of times weaker than the body’s own hormones. Their main action appears to be helping regulate hormone activity rather than replacing male hormones.
The same mechanisms that may help protect hormone-sensitive tissues in women may also support prostate health in men. Research into prostate enlargement and prostate cancer is ongoing and early findings are encouraging, although more human studies are needed.
And yes—some traditional Caribbean drinks made with flaxseed are even regarded as aphrodisiacs. Whether that’s the flaxseed, the condensed milk or the generous splash of rum is perhaps best left open to debate!
Metabolic Health
Some studies suggest lignans may improve insulin sensitivity and contribute to better blood sugar control.
The evidence is less consistent than for cardiovascular health, but there are encouraging signs that lignans may help support healthy metabolism as part of an overall nutritious diet.
Why Grind Flaxseed?
The lignans are stored inside the seed’s tough outer structure.
Whole flaxseed often passes through the digestive system largely intact, meaning many of the lignans remain trapped inside.
Grinding the seed breaks open this natural protective coat, allowing digestive enzymes and beneficial bacteria access to the lignans.
Freshly ground flaxseed therefore provides considerably greater access to these valuable compounds than eating the seeds whole.
What is High-Lignan Flax Oil?
Most ordinary flaxseed oil contains very little lignan because the lignans remain in the seed after the oil has been pressed.
High-lignan flax oil is produced by adding specially prepared flax lignan extract back into the oil. This provides the healthy omega-3 fats naturally present in flaxseed together with many of the beneficial lignans that would otherwise be lost.
(See our page on High-Lignan Flax Oil for more information.)
A Balanced View of the Evidence
Lignan research is one of the fastest-growing areas of nutritional science.
Many of the most exciting findings come from laboratory studies, animal research and large population studies. Human clinical trials generally show smaller—but still encouraging—benefits.
The Budwig Diet does not depend on any single nutrient producing dramatic results. Instead, it combines many natural foods that each make a small contribution towards helping the body function as it evolved to do. Lignans are one important part of that overall picture.
As with all nutrition, individual responses vary. Your existing gut microbiome, your overall diet and your general health all influence how effectively your body converts flax lignans into their active forms.