Isoflavone

Isoflavones are a type of naturally occurring isoflavonoids that are produced almost exclusively by the members of the bean family, Fabaceae (Leguminosae)[1]. They are substituted derivatives of isoflavone, which is an isomer of flavone, with the phenyl group located in the 3-position instead of the 2-position[1]. Isoflavones are known for their estrogenic activity and are classified as phytoestrogens, meaning they can mimic the action of estrogens in the body[1][5].

Occurrence and Sources

Isoflavones are found primarily in legumes, with soybeans being the most common source in human food[1][2]. The major isoflavones in soybean are genistein and daidzein[1]. Other dietary sources of isoflavones include chickpeas, beans, fruits, vegetables, and nuts[2]. Red clover products are also used in human dietary supplement production for the reduction of menopausal symptoms in women[2].

Biological and Health Effects

Isoflavones have been associated with potential health benefits, including a reduced risk of postmenopausal cancer and osteoporosis in women[1]. They may also act as substrates for thyroid peroxidase, competitively inhibiting thyroid hormone production. However, there is insufficient data on the safety and adverse effects of isoflavone supplements, and their use as an alternative therapy for hormonal disorders is still being researched[2].

Metabolism and Bioavailability

The metabolism of isoflavones involves conversion from glycosylated forms to aglycones, which can occur in the oral cavity, intestines, and large intestines[3]. The bioavailability of isoflavones is influenced by their chemical form, with aglycones having higher biological activity than glycosylated forms[5]. Lipid-based formulations and complexation with cyclodextrin have been explored to improve the bioavailability of isoflavones[5].

Research and Controversies

While some studies suggest that isoflavones may have health benefits, the evidence is not conclusive, and there are concerns about their potential risks, particularly for women with a history of breast cancer[1]. The European Food Safety Authority has found no adverse effects with intakes up to 150 mg/d, but has criticized the lack of data. Further research is needed to fully understand the effects of isoflavones on human health[1][2].

Citations:

[1] https://en.wikipedia.org/wiki/Isoflavone

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6470817/

[3] https://go.drugbank.com/drugs/DB12007

[4] https://www.verywellhealth.com/isoflavones-benefits-side-effects-dosage-and-interactions-4687017

[5] https://pubmed.ncbi.nlm.nih.gov/23161396/