Women's Health | November 8, 2017 | Author: Naturopath
Phytoestrogens, put simply, are chemicals from plants which have oestrogenic activity. Meaning they resemble our own hormone - oestrogen and can interact with the cells that have oestrogen receptors in our body. The major groups of phytoestrogens present in our diet are isoflavones, prenylflavonoids, coumestans and lignans.
The beneficial health effects from phytoestrogens are based on their structural similarity to 17‐β‐oestradiol (E2), which is the main primary female hormone. This allows them to bind to oestrogen receptors (ER) and cause oestrogenic and (anti)oestrogenic effects.
Two main oestrogen receptor α (ERα) and oestrogen receptor β (ERβ) have been identified in humans.
Due to these ER subtypes having different roles in gene regulation, cancer biology and therapy, the cellular response may differ toward different phytoestrogens consumed.
Several classes of photochemical compounds interact with oestrogen receptors with the most well-known being isoflavones and lignans.
The main isoflavones are genistein, daidzein, glycitein, formononetin and biochanin A, which are mainly found in soy, soy‐based food and legumes.
Isoflavones have had research interest due to their affinity for oestrogen receptors with scientist researching safer and alternative options to HRT (Hormonal replacement therapy). Research has found that isoflavones compete strongly with endogenous oestradiol (our own primary sex hormone) at oestrogen receptors but their stimulating action is weaker than oestradiol. What they are able to do is work as antagonist or agonist depending on the hormonal environment.
Isoflavones may have a balancing effect addressing either excess as in premenstrual syndrome, or decreased oestrogen levels as in menopause.
The isoflavones of oestrogenic value include genistein, daidzein and their glycosides. Natural foods that have oestrogenic isoflavones include soy bean and other legumes such as mung beans, chickpeas and alfalfa.
Soy and soy products have the highest amount of isoflavones in the human diet.
Soy is a legume from the Leguminosae (pea family) and is used to make products such as natto, tofu, tempeh and miso and whole soy milk. Bowel flora plays a role in the degradation of isoflavones with differing soy food sources and individual bowel flora influencing the absorption and consequent action obtained.
Red clover (trifolium pratense) is a plant from the Fabaceae family that has been researched for its potential as an oestrogenic agent that is safer treatment than HRT, its isoflavones being structurally simular to 17‐β‐oestradiol. Both the leaves and flowers have been found to have significant phytooestrogenic activity and extracts in vivo were found to also bind to progesterone and androgen receptor sites.
A study using Red clover extract and probiotics helped potently reduce bone mineral density (BMD) loss caused by estrogen deficiency, improved bone turnover, promoted a favourable estrogen metabolite profile (2-OH:16α-OH), and stimulated equol (metabolised isoflavone) production in postmenopausal women with osteopenia. Red clover extract intake combined with supplementation (calcium, magnesium, and calcitriol) was more effective than supplementation alone.
Data suggesst that breast cancer patients may need to avoid red clover and isoflavone based products when making choices for menopausal symptom relief.
Lignans are polyphenols - polyphenols are micronutrients found in certain plant-based foods. Polyphenols have an abundance of antioxidants and potential health benefits for digestive issues, weight management, diabetes, neurodegenerative disease, and cardiovascular diseases as well as phyto oestrogenic effects in the body. Lignan precursors can be found in plant based foods such as seeds, nuts, legumes, whole grains, fruit and vegetables.
Linseeds (Linum usitatissimum) have been found to provide the riches source of oestrogenic lignans enterodiol and enterolactone. These components are produced from the action of gut flora and are structurally simular to oestrogen and tamoxifen.
Although taking linum failed to increase bone density in post-menopausal women, it was found to help mild menopausal symptoms and reduce blood pressure in women with cardiovascular disease under stress.
Perhaps one of its greatest influences in its ability to alter hormone metabolism - this is of great importance in being able to remove from the body the metabolites of oestrogen which could be a causative factor in breast cancer.
Linseeds are also a great source of alpha lipoec acid. Diets high in ALA and fibre have been associated with decreased incident of some cancers and supplementation showed to reduced levels of proliferation and invasiveness of tumours in those with primary breast cancer.
Flax has been cultivated for its oil and fibre and is approved by German Commission E for its internal use in the treatment of constipation, irritable bowel, diverticulitis, gastritis, enteritis and externally for inflammation. This is due to is laxative, demulcent and emollient qualities. The oil of the flaxseeds has very high levels of ALA, an omega fatty acid, associated with having a protective effect against cardiovascular disease. ALA supplement from linseeds were found to decrease levels of inflammatory markers, reduce markers of atherosclerosis in dyslipidaemic patients (people with abnormal amounts of triglycerides, cholesterol and other fats/lipids in the blood) and raise EPA/DHA levels in the blood (although not as well as using fish oil).
Ground linseed seeds were found to be of benefit to prevent cardiovascular disease risk factors in young women, post-menopausal women (including those with mild hypercholesterolaemia), hyperlipidaemic patients, and in type 2 diabetics (reducing blood clotting tendencies).
Linseeds can be used whole but the benefits are greater when they are crushed or better still ground.
They are heat stable so can be included in baked goods and store well.
If using them for better bowel function, seeds may be soaked to increase the mucilage or drink 1-2 glasses of water after consuming. Add to yoghurt, breakfast cereals, shakes, baked muffins or even sprinkle on your salad. Aim for 20-30 grams daily for therapeutic results.
Phytoestrogens are being studied as potential alternatives to other medicines as they exert cardio-protective mechanisms via estrogen receptors.
Phytoestrogens have a complex role, acting as weak estrogens and anti oestrogens depending on the tissue they are targeting. Signaling pathways influenced by phytoestrogens are not completely identical to those induced by oestrogens.
There has been no adverse effects found from lignans and isoflavones consumed in the diet. Therapeutic amounts should be used with caution with certain drugs - such as tamoxifen.
Incorporating soy based products and lignans from seeds, nuts, legumes, whole grains, fruit and vegetables and especially linseeds can have a gentle action on hormonal based symptoms where there is a deficiency or excess or poor clearance of oestrogen from the body.
Mills S, Bone K, (2009), Principles and Practice of Phototherapy, Elsevier, Aust
Fisher, C; (2009), Materia Medica of Western Herbs, New Zealand
Red Clover Aryl Hydrocarbon Receptor (AhR) and Estrogen Receptor (ER) Agonists Enhance Genotoxic Estrogen Metabolism. https://www.ncbi.nlm.nih.gov/pubmed/28985473
Combined bioavailable isoflavones and probiotics improve bone status and estrogen metabolism in postmenopausal osteopenic women: a randomized controlled trial. https://www.ncbi.nlm.nih.gov/pubmed/28768651
Phytochemicals Targeting Estrogen Receptors: Beneficial Rather Than Adverse Effects? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5535874/
Potential phytoestrogen alternatives exert cardio-protective mechanisms via estrogen receptors https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5479424/
The potential health effects of dietary phytoestrogens https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5429336/