Strong evidence for lignans' breast cancer protection
cancer for pre-menopausal women by 78 per cent, says new research
from Germany that adds significantly to the current body of
Plant lignans, from sources such as flax seed, whole grain cereals, berries, vegetables and fruits, are metabolised in the colon by microflora into enterodiol and enterolactone.
Lignans are well-known phytoestrogens - active substances derived from plants that have a weak oestrogen-like action that have been linked before to breast health, as well as benefits for postmenopausal women.
The new study, published in the European Journal of Cancer Prevention (Vol. 15, pp. 225-232), reports that women with high plasma levels of enterolactone (above 12.96 nanomoles per litre), linked to high lignan intake, was associated with a 58 per cent reduction of breast cancer risk.
"To the best of our knowledge, this is the first study to investigate both calculated enterolactone on the basis of food intake and data from biomarker measurement (plasma enterolactone) in relation to breast cancer risk," wrote lead author Regina Piller from the Technical University of Munich.
It should be stressed that this new study does not mention which source of lignans, if any in particular, the women were taking, but merely looked at total lignan intake, as well as plasma levels of the metabolite, enterolactone.
The population-based case-control study, conducted in two regions in Germany, used dietary intake data, collected by a 176-item food frequency questionnaire, and biomarker data from blood samples for 192 pre-menopausal cases (women with in-situ or invasive breast cancer) and 231 matched controls (average age for all subjects was 42).
The researchers found that the controls had higher plasma levels of enterolactone: 9.7 nanomoles per litre versus 6.3 nanomoles per litre for the cases.
It was also found that, when the risk of breast cancer was measured in terms of plasma enterolactone levels, a higher intake was associated with a significantly lower risk.
Average plasma enterolactone levels of 12.96 nanomoles per gram was associated with a 58 per cent reduction in breast cancer risk, while average plasma enterolactone levels of 24.96 nanomoles per gram was associated with a reduction of 62 per cent.
When calculated in combination with lignan intake, similar results were observed. A high intake of enterolignans (enterodiol and enterolactone) on the basis of dietary intake (846 micrograms per day) combined with a high plasma enterolactone level was associated with a reduction in the risk of breast cancer of 64 per cent.
"In the present case-control study the same results obtained from using both types of exposure data lend greater credibility to an inverse association between lignan intake and the premenopausal breast cancer risk," said the researchers.
No association was found between dietary and/or plasma levels of the soy isoflavone genistein.
"These results add to the scientific evidence of a possible beneficial effect of a high lignan intake during a woman's reproductive years in terms of a decreases breast cancer risk," concluded Piller.
The research has been welcomed by Acatris, producer of LinumLife -secoisolariciresinol diglucoside (SDG) from flaxseed, and Linnea, manufacturer of HMRlignanT (hydroxymatairesinol) from Norwegian spruce.
Jocelyn Mathern, RD for Acatris told NutraIngredients.com: "This is another of many studies showing that lignans are beneficial for breast health, which is great news for women considering that breast cancer diagnosis is on the rise."
Mathern said that previous studies have shown that flaxseed or purified SDG improve a woman's oestrogen profile in a way that reduces the risk for breast cancer
While the results of this new study do not make mention to which source of lignans, Mathern said that Acatris is expecting results of a study in women looking at the effects of their flaxseed extract, LinumLife, on markers of breast cancer.
"We hope to confirm that SDG, the main flax lignan, is largely responsible for the beneficial effects seen in previous flaxseed studies looking at breast health," said Mathern.
"While there are other sources of lignans entering the market, it is important for people to examine the science. Lignans from sources other than flax are metabolized differently by the body," she said.
Linnea, producer of the HMRlignan from Norwegian spruce - one of the other sources of lignans - also welcomed the results of the study.
According to Linnea, HMRlignan is suitable for stand-alone or multi ingredient supplements as only a small dose is needed - just 10 to 40mg to elevate the enterolactone level to the same degree as three tablespoons of lignans from unground flax seed.
Robin Ward, vice president of marketing for Linnea, said that there are now seven studies reporting an association between lignan intake and breast health.
"Research has shown enterolactone to stimulate the synthesis and circulating levels of a biochemical called sex hormone-binding globulin (SHBG). Through this activity, enterolactone may reduce the free bioavailable pool of circulating oestrogen, thereby reducing estrogen penetration in tissues and the risks of an adverse oestrogen balance," Ward explained.
"There is also evidence that enterolactone may inhibit biosynthesis of oestrogen by blocking aromatase, a key enzyme in biosynthesis of estradiol. Collectively through these multiple mechanisms of action, lignans appear to have a positive influence on the oestrogen balance in the body," he said.
Over one million women worldwide are diagnosed with breast cancer every year, with about 400,000 new cases in Europe. China has the lowest incidence and mortality rate of the disease.