You’ve probably heard about the health benefits of soy phytoestrogens. These naturally occurring estrogen-like compounds are beneficial for bone and heart health, and menopausal symptoms. Although most research has focused on soy phytoestrogens, plant lignans are the primary source of dietary phytoestrogens in the Western diet.
What are plant lignans?
Lignans are compounds that form the building blocks of plant cell walls. They contain phytoestrogens that help regulate the body’s estrogen production. When we eat plant foods the lignan compounds are converted in our intestines by good bacteria to produce a form that the body can assimilate. Enterolactone—the primary lignan metabolite (a substance produced by metabolism) that circulates in our blood—produces weak estrogenic activity. Dozens of reports have revealed that high levels of enterolactone in our blood help to reduce risk of breast, prostate and colon cancers, and cardiovascular disease. Studies have also shown that high levels of lignans can support healthy weight and glucose metabolism, reducing the risk of insulin sensitivity, metabolic syndrome and diabetes.
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Benefits for women and men
- Plant lignans have been shown to:
- promote breast health
- reduce hot flashes in women by more than 50%
- support prostate health
- provide cardiovascular support
- support healthy blood glucose metabolism
- support healthy body weight
- provide antioxidant and anti-inflammatory support
How do plant lignans work in the body?
When you eat foods that contain lignans the bacteria in your gut converts them into metabolites that produce a weak estrogenic effect. Estrogens are small molecules that control numerous reactions in the body. The lignan metabolite enterolactone provides estrogenic support when estrogen levels are low, making up for some of the deficiency. When estrogen levels are too high, the lignans attach to the estrogen receptors, reducing the activity of your body’s natural estrogen hormones and blocking their effect in certain tissues. Research has shown that lignan phytoestrogens help prevent some forms of cancer 1,2,3 in this way, by blocking estrogenic activity.
What foods contain lignans?
Most plant foods contain small amounts of lignans, but flax seeds are by far the best source. Other good sources include high fiber foods such as whole grains, sesame seeds, sunflower seeds, cashews, kale, broccoli and berries.
Why should you take a lignan dietary supplement?
Most of us don’t eat enough unrefined grains, fruits, vegetables, nuts and legumes necessary to provide the plant lignans we need to benefit our health. The average intake of lignans in the U.S. is only about 1 milligram per day. Yet, researchers say that we need a minimum of 50 to 100 milligrams of lignans per day in order to raise our enterolactone levels.
You’d have to eat 3 to 4 tablespoons of unrefined flax seed every day to maintain healthy blood levels of enterolactone, and/or a very large amount of unrefined grains, nuts and beans, which most of us aren’t used to. You could also think of it this way: Very few Westerners get the required daily amount of fiber (23-30 mg) that provides an optimal amount of plant lignans.
How efficiently you metabolize lignans depends on a number of factors. Some of us lack adequate gut bacteria needed to convert plant lignans to the forms we can use. This could be the result of taking antibiotics, which destroy healthy bacteria. Some of us have food allergies or sensitivities that interfere with the conversion and assimilation processes. Inflammatory bowel disease or a high-fat diet can also influence how efficiently we metabolize plant lignans. But for most of us who eat a Western diet, we simply do not eat enough high-fiber plant foods, the richest source of lignans.
• Lignans significantly reduce hot flashes in menopausal women
Since enterolactone (the main lignan metabolite) helps with estrogen balance researchers have found that it is a safe and natural alternative to help buffer the hormonal fluctuations during menopause. This in turn helps to alleviate the accompanying symptoms of hot flashes and night sweats.
A recently completed U.S. clinical study found that HMRlignanTM —a dietary lignan supplement—effectively reduced hot flashes by 53% in postmenopausal women. The pilot study compared the effect of 2 doses of HMRlignanTM (25 mg and 50 mg per day) over an 8-week period. Compared to baseline (pre-treatment), women taking 50 mg of HMRlignanTM per day had a significant reduction in the number of hot flashes after just 4 weeks. At 8 weeks, the reduction in daily hot flashes was approximately 50% less than at the start of treatment. 8
• The higher your enterolactone levels, the lower your risk of breast cancer
Studies support the hypothesis that low blood levels of enterolactone are associated with a higher incidence of breast cancer. A meta-analysis of the relationship between lignans and breast cancer risk included studies published between 1997 and August 2009. The researchers analyzed 21 studies and found that postmenopausal women with a higher intake of lignans had a lower risk of breast cancer. 9
A study of 58,000 French women measured the amount of plant lignans the women were ingesting and its effect on the prevalence of breast cancer over a 7-year period. It’s important to note that the women did not take soy isoflavone supplements during this time. In all, 1469 cases of breast cancer were diagnosed. Compared with women who ingested the lowest amount of plant lignans, the women who consumed the most (more than 1395 micrograms per day) had a reduced risk of breast cancer. 10
• Plant lignans inhibit the growth of prostate cancer cells
Although no human clinical trials have been done yet, researchers discovered that when laboratory animals with the equivalent of human prostate cancer were fed a diet that included plant lignans over a 9-week period, the diet inhibited the growth of cancer cells and tumors. There was also an increased proportion of tumors that stopped growing, as well as cancer cells that died (apoptosis) in the lignan-diet group when compared to the control group. 11
This is good news for men, since statistics show that 1 man out of 6 will get prostate cancer during his lifetime. Eating more plant foods, and taking a natural lignan supplement are easy ways to reduce risk and to help stop the growth of prostate cancer cells.
• Lignans offer natural heart health protection
Increased blood levels of enterolactone have been shown to reduce oxidation of blood lipids and reduce risk of heart disease by offering antioxidant and anti-inflammatory protection. 4 A recent review of all the studies on the potential that dietary lignans have on reducing cardiovascular disease indicate that they can reduce C-reactive protein (a biomarker of inflammation), and lower LDL “bad” cholesterol. 5
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Olsen A, Knudsen KE, Thomsen BL, Loft S, Stripp C, Overvad K, Møller S, Tjønneland A. Plasma enterolactone and breast cancer incidence by estrogen receptor status. Cancer Epidemiol Biomarkers Prev. 2004 Dec;13(12):2084-9.
Bylund A, Saarinen N, Zhang JX, Bergh A, Widmark A, Johansson A, Lundin E, Adlercreutz H, Hallmans G, Stattin P, Mäkela S. Anticancer effects of a plant lignan 7-hydroxymatairesinol on a prostate cancer model in vivo. Exp Biol Med (Maywood). 2005 Mar;230(3):217-23.
Qu H, Madl RL, Takemoto DJ, Baybutt RC, Wang W. Lignans are involved in the antitumor activity of wheat bran in colon cancer SW480 cells. J Nutr. 2005 Mar;135(3):598-602.
Vanharanta M, Voutilainen S, Rissanen TH, Adlercreutz H, Salonen JT. Risk of cardiovascular disease-related and all-cause death according to serum concentrations of enterolactone: Kuopio Ischaemic Heart Disease Risk Factor Study. Arch Intern Med. 2003 May 12;163(9):1099-104.
Peterson J, Dwyer J, Adlercreutz H, Scalbert A, Jacques P, McCullough ML. Dietary lignans: physiology and potential for cardiovascular disease risk reduction. Nutr Rev. 2010 Oct;68(10):571-603. doi: 10.1111/j.1753-4887.2010.00319.x.
Kim MK, Chung BC, Yu VY, Nam JH, Lee HC, Huh KB, Lim SK. Relationships of urinary phyto-oestrogen excretion to BMD in postmenopausal women. Clin Endocrinol (Oxf). 2002 Mar;56(3):321-8.
Boulbaroud S, Mesfioui A, Arfaoui A, Ouichou A, el-Hessni A. Preventive effects of flaxseed and sesame oil on bone loss in ovariectomized rats. Preventive effects of flaxseed and sesame oil on bone loss in ovariectomized rats. Pak J Biol Sci. 2008 Jul 1;11(13):1696-701.
Cosentino M. New clinical research – the HMRlignanTM strategy for sustainable women’s health support. Presented May 9, 2007 at Vitafoods, Geneva, Switzerland.
Buck K, Zaineddin AK, Vrieling A, Linseisen J, Chang-Claude J. Meta-analyses of lignans and enterolignans in relation to breast cancer risk. Am J Clin Nutr. 2010 Jul;92(1):141-53. Epub 2010 May 12.
Touillaud, MS, Thiébaut, ACM, Fournier, A, et al. Dietary Lignan Intake and Postmenopausal Breast Cancer Risk by Estrogen and Progesterone Receptor Status. J Natl Can Inst, 2007;99(6):475-486.
Bylund A,a et al. Anticancer effects of a plant lignan 7-hydroxymatairesinol on a prosate cancer model in vivo. Exp Biol Med (Maywood) 2005 Mar;230)3):217-23.
Morisset AS, Lemieux A, Veilleux J, SJ Bergeron, A Weisnagel, Tchernof A. “Impact of a lignan-rich diet on adiposity and insulin sensitivity in post-menopausal women” British Journal of Nutrition. 2009, 102: 195-200. Published online ahead of print, First View, doi:10.1017/S0007114508162092