What Are Lignans?
Lignans are a group of phytonutrients (plant nutrients) which are found in
seeds, grains and vegetables. Flax seed is, by far, nature's richest source of plant lignans, such as rye,
buckwheat, millet, soya, and barley, and contain 2 to 6 micrograms of lignans per gram (mcg/g) of
Flax seed yields 800 mcg/g. While the essential fatty acids are in the oil
of the flax seed, the lignans are in the fiber hull of the seed. The oil has little or no lignans.
The lignan found in flaxseed is called secoisolariciresinol
diglucoside (SDG). This phytonutrient is classed as a polyphenol.
Flaxseed lignan was discovered in 1956. The first interest in
biological activity of SDG arose in the early 1980's when investigators reported that the level of lignans in
the body were lower in patients with breast cancer than in tumor free patients. It was also noted that
vegetarians had higher concentrations of lignan substances than non-vegeterians.
There are two general types of lignans: 1) those found in
plants and 2) those found in animals and humans or "mammalian lignans." When the plant lignan SDG (from
flaxseed) is ingested, it is converted in the colon by bacteria to the mammalian lignans enterodiol (ED) and
Many studies have shown the important health benefits that
exist due to this conversion of flax lignan in the body.
The essential fatty acids in flax oil are the best known
constituent in flaxseed for providing health benefits.They have been proven to helps prevent heart disease,
improve skin and hair, aid in the cell production, aid in fat and weight reduction as well as other health
benefits. Flax oil has become one of the most beneficial and sought after health products in the
While most of the attention surrounding flax seed has been its
source of essential fatty acids, recent studies and research have revealed that the substance called "lignan"
within flaxseed may surpass flax oil in its health benefits.
Since 1995, several health products have come into the
markerplace with the word "lignan" on the label. Several flax oil products claim to contain lignans. They
have names like "high Lignan Flax Seed Oil".
When these products were tested it was found they contained
practically no lignans at all. That is to be expected since the lignans are not in the oil.
Other flax oil products state they contain a certain percentage
of lignan particulates such as "20% lignan particulates." This does not mean it contains 20% lignans. This
means that 20% of the product is made up of pieces of the flax fiber shell which contains the
Since the fiber meal consists of about 1.6% lignans, such a
product would contain only .35% Lignans. Futher, if such a product is in liquid form (in the bottle), the
particulates will settle to the bottom. Thus no lignans are consumed until the end of the product's
Another product says it has "up to 30% more lignans that the
whole flax seed." This is essentially a product consisting mostly of the defatted flax fiber without the
There is no concentration or extract of lignans. Such a product
would thus contain about 1.6% lignans, which is the highest level of lignans currently
Health product companies have tried to capitalize on the
tremendous health benefits of lignans by offering lignan products. They have been able to get the word
"lignan" on the label, but little of it in the product.
Some of these flax products advertise that flaxseed has 100 to
800 times more lignans than other plant sources. This sounds impressive but they do not say how little lignan
there actually is in a flax seed: just 1%. If it is a flax oil product, it does not matter anyway, since less
than 2% of the lignans are in the oil.
The difficulty in separating SDG lignan from flaxseed lies in
the fact that the flaxseed hulls, which contain the lignan, adhere tightly to the seed. Therefore, obtaining
a pure SDG product has not been economically viable.
The University of Toronto developed an SDG extraction process
using chemicals such as methanol, petroleum ether, chloroform, sodium methoxide and sulfuric acid. The method
is not very desirable due to trace chemicals leeching into thelignans.
Another Method uses an alkaline alcohol process followed by
flash chromatography. The yield, however, is ratter low. Finally a new revolutionary and highly proprietary
process has been developed to provide the highest possible, all natural concentration of SDG containing flax
Antioxidants and Disease
It is now known that some diseases, including cancer, can get
their start or be promoted by way of free radical damage. There has been an increase in the causes of
free radicals in the body, such as high unhealthy-fat diets, fried foods, exposure to radiation, and
The normal antioxidants (vitamins A, C, E and phytochemicals)
are not able to keep up with the increase in free radicals. The balance between your intake of
antioxidants and exposure to free radicals may literally be the balance between health and disease or life
Previously the ability of flax seed to scavenge oxygen radicals
(antioxidant properties) was not known. Recent research has proven the ability of SDG to scavenge
hydroxyl radicals. The results showed that SDG has potent antioxidant activity.
At the University of British Columbia, SDG and its mammalian
lignans enterodiol (ED) and enterolactone (EL) were evaluated in both lipid and aqueous in vitro model
All three lignans significantly inhibited the linoleic acid
peroxidation and hydroxyl radicals, with ED and EL providing more scavenging activity than SDG. It was
included that there is an efficacy of SDG and particularly the mammalian lignans ED and EL to act as
This is evidence of a protential anticarcinogenic mechanism in
the flaxseed lignan SDG and ED and EL.
In a Study at the University of Saskatchewan College of
Medicine, tests were performed to determine the effectiveness and potency of SDG isolated from flaxseed as an
antioxidant, along with its mammalian metabolites secoisolariciresinol (SECO), Enterodiol (ED) and
Vitamin E was also tested for a comparison. The results of
the tests show that the metabolities of SDG have strong antioxidant activity. In comparison to vitamin E, SDG
was 1.27 times more potent as an antioxidant.
However, the lignan EL was 4.35 times, more potent, SECO was
4.86 times more potent, and ED was 5.02 times more potent than vitamin E.
The above studies showed that the higher the concentration of
SDG, the greater the antioxidant effect.
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