The role of the microbiome in phytoestrogens
Phytoestrogens are naturally occurring plant compounds that, due to their molecular structure and size, resemble human oestrogens. The new NICE draft guidelines have said that they can be considered for the use in menopause for the improvement of hot flushes.
Phytoestrogens can be divided into two main groups: flavonoids and non-flavonoids. Flavonoids include isoflavones; the main source of isoflavones are legumes, namely soybean as a source of daidzein and red clover as a source of formononetin (which is effectively transformed into daidzein in the human gastrointestinal tract).
Daidzein passes to the large intestine, where it is acted on by intestinal microflora to create equol. Laboratory studies proved that equol is more bioactive, more oestrogenic, and a more potent antioxidant than the source form daidzein. About 40–70% of the adult population do not excrete equol in the urine, even if they have consumed soybean products or pure isoflavones, because, for a reason that is not known, they do not harbour specific intestinal bacteria involved in the metabolism of daidzein to equol.
Isoflavones can be used as an alternative therapy for a wide range of hormonal disorders, including menopausal symptoms. Only women able to produce equol (detected in the urine) noticed a reduction in menopausal symptoms when taking soybean isoflavone supplements.
Concrete bacterial strains involved in the isoflavone metabolism are not known and these issues are currently being addressed. Current suspected species include Bifidobacteria sp. (B. breve and B. longum). In the UK, Optibac Everyday has both of the Bifidobacteria species included in it.
The prebiotic inulin has also been found to increase equol production.
There is still further research required into this area before concrete recommendations can be given If you decide to trial using phyoestrogens but don’t notice an improvement in your symptoms it may be worth trialing specific probiotics with the prebiotic inulin to see if this improves your symptoms.
References
Mustafa SE, Mustafa S, Ismail A, Abas F, Abd Manap MY, Ahmed Hamdi OA, Elzen S, Nahar L, Sarker SD. Impact of prebiotics on equol production from soymilk isoflavones by two Bifidobacterium species. Heliyon. 2020 Oct 23;6(10):e05298. doi: 10.1016/j.heliyon.2020.e05298. PMID: 33134584; PMCID: PMC7586118.