The impact of equol-producing status in modifying the effect of soya isoflavones on risk factors for CHD: a systematic review of randomised controlled trials

Abstract

Recent studies suggest that the ability to produce equol, a metabolite of the soya isoflavone daidzein, is beneficial to coronary health. Equol, generated by bacterial action on isoflavones in the human gut, is biologically more potent than dietary sources of isoflavones. Not all humans are equol producers. We investigated whether equol-producing status is favourably associated with risk factors for CHD following an intervention by dietary soya isoflavones. We systematically reviewed randomised controlled trials (RCT) that evaluated the effect of soya isoflavones on risk factors for CHD and that reported equol-producing status. We searched PubMed, EMBASE, Ovid Medline and the Cochrane Central Register for Controlled Trials published up to April 2015 and hand-searched bibliographies to identify the RCT. Characteristics of participants and outcomes measurements were extracted and qualitatively analysed. From a total of 1671 studies, we identified forty-two articles that satisfied our search criteria. The effects of equol on risk factors for CHD were mainly based on secondary analyses in these studies, thus with inadequate statistical power. Although fourteen out of the forty-two studies found that equol production after a soya isoflavone intervention significantly improved a range of risk factors including cholesterol and other lipids, inflammation and blood pressure variables, these results need further verification by sufficiently powered studies. The other twenty-eight studies primarily reported null results. RCT of equol, which has recently become available as a dietary supplement, on CHD and its risk factors are awaited.

Biomarkers of legume intake in human intervention and observational studies: a systematic review

“…For example, daidzein and genistein were reported to have a synergistic effect on inhibiting cell proliferation and inducing apoptosis of prostate cancer cells [ 14 ]. In addition, these compounds and equol were also proposed to be antiestrogenic, antioxidative, and anticarcinogenic and may protect against chronic diseases such as hormone-dependent cancer, cardiovascular diseases, and osteoporosis [ 15 – 19 ]. However, it is worth noting that a few studies considering estrogenic effects of dietary soy phytoestrogens have demonstrated that the isoflavones promote growth of ER-positive breast cancer cells under both in vitro as well as in vivo conditions [ 20 – 22 ].…”

Evaluation of inter-individual differences in gut bacterial isoflavone bioactivation in humans by PCR-based targeting of genes involved in equol formation

“…; Birru et al . ; Frankenfeld ). The definition of the equol producer phenotype is currently based on urinary or serum equol concentrations.…”

“…By doing so, a number of human randomized controlled trials found beneficial effects of soy intake in equol-producing subjects but not in nonproducers. Those effects include improvement of risk factors for breast cancer, prostate cancer, cardiovascular disease and alleviation of osteoporosis (Shor et al 2012;Birru et al 2016;Frankenfeld 2017). The definition of the equol producer phenotype is currently based on urinary or serum equol concentrations.…”

Phase 1 and Pharmacokinetic Drug–Drug Interaction Study of Metformin, Losartan, and Linagliptin Coadministered With DW1029M in Healthy Volunteers

“…The soya isoflavone daidzein has strong anti‐inflammatory activity and affects various mechanism pathways including the NF‐κB, p38MAPK, and TGF‐ β1 pathways . Recent clinical studies have suggested that the ability to produce equol, a metabolite of the soya isoflavone daidzein, is beneficial against coronary heart disease . Puerarin and daidzein are the major bioactive isoflavonoids isolated from Puerariae radix .…”

“…27 Recent clinical studies have suggested that the ability to produce equol, a metabolite of the soya isoflavone daidzein, is beneficial against coronary heart disease. 28,29 Puerarin and daidzein are the major bioactive isoflavonoids isolated from Puerariae radix. DW1029M protects against diabetic complications such as DN and diabetic retinopathy through the inhibition of advanced glycosylation end product formation rat lens aldose reductase activity, and TGF-β1 signaling.…”