The potential health effects of dietary phytoestrogens

Abstract

Phytoestrogens are plant-derived dietary compounds with structural similarity to 17-β-oestradiol (E2), the primary female sex hormone. This structural similarity to E2 enables phytoestrogens to cause (anti)oestrogenic effects by binding to the oestrogen receptors. The aim of the present review is to present a state-of-the-art overview of the potential health effects of dietary phytoestrogens. Various beneficial health effects have been ascribed to phytoestrogens, such as a lowered risk of menopausal symptoms like hot flushes and osteoporosis, lowered risks of cardiovascular disease, obesity, metabolic syndrome and type 2 diabetes, brain function disorders, breast cancer, prostate cancer, bowel cancer and other cancers. In contrast to these beneficial health claims, the (anti)oestrogenic properties of phytoestrogens have also raised concerns since they might act as endocrine disruptors, indicating a potential to cause adverse health effects. The literature overview presented in this paper illustrates that several potential health benefits of phytoestrogens have been reported but that, given the data on potential adverse health effects, the current evidence on these beneficial health effects is not so obvious that they clearly outweigh the possible health risks. Furthermore, the data currently available are not sufficient to support a more refined (semi) quantitative risk-benefit analysis. This implies that a definite conclusion on possible beneficial health effects of phytoestrogens cannot be made.

Linked articles: This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Figure 1

Chemical structures of E2 and the most common phytoestrogens.

Figure 2

Chemical structures of some dietary lignan precursors.

Figure 3

(A) Binding affinities to ERα and ERβ (expressed as IC₅₀ values) and (B) effect concentrations in ERα and ERβ reporter gene assays (expressed as EC₅₀ values) of E2 and phytoestrogens. In Tables S1 and S2, the IC₅₀ and EC₅₀ values, respectively, and the references to the literature are presented.

Figure 4

Induction of oestrogen responsive element mediated luciferase activity in the ERα‐ and ERβ‐containing U2OS reporter cell lines by (A) E2 and (B) genistein. For further details, see Rietjens et al. (2013).

Figure 5

Schematic presentation summarizing the possible health effects of phytoestrogens and the potential underlying modes of action as presented in the present paper.