Epidemiological studies suggest that soya consumption as a source of phyto-oestrogens and isoflavones may be associated with a reduced risk of colorectal cancer. However, findings have not yet been synthesised for all groups of phyto-oestrogens. A meta-analysis was conducted to quantify the association between phyto-oestrogens and colorectal cancer risk. Relevant observational studies published up to June 2016 were identified by searching MEDLINE, EMBASE and Cochrane Library databases. Study-specific relative risks (RR) were pooled in both categorical and dose–response meta-analyses. Out of seventeen identified studies, sixteen were included in the meta-analysis. Comparing the highest with the lowest intake category, inverse associations for phyto-oestrogens overall and by subgroup were observed but were statistically significant in case–controls studies and not in cohort studies. The pooled RR in case–control studies were 0·76 (95 % CI 0·69, 0·84), 0·77 (95 % CI 0·69, 0·85) and 0·70 (95 % CI 0·56, 0·89) for phyto-oestrogens, isoflavones and lignans, respectively, whereas the corresponding pooled RR were 0·95 (95 % CI 0·85, 1·06), 0·94 (95 % CI 0·84, 1·05) and 1·00 (95 % CI 0·64, 1·57) in cohort studies. Dose–response analysis yielded an 8 % reduced risk of colorectal neoplasms for every 20 mg/d increase in isoflavones intake in Asians (pooled RR 0·92; 95 % CI 0·86, 0·97). A non-linear inverse association with colorectal cancer risk was found for lignans intake, but no association for circulating enterolactone concentrations was observed. Thus, study heterogeneity precludes a rigorous conclusion regarding an effect of high exposure to isoflavones on risk of colorectal cancer. Current evidence for an association with lignans exposure is limited. Further prospective studies, particularly evaluating lignans, are warranted to clarify the association between different phyto-oestrogens and colorectal cancer risk.

The expression of oestrogen receptors (ERα and ERβ) in the prostate and uterus tissues of Wistar rats supplied for 8 weeks with a diet rich in sesame (Sesamum indicum) pericarp (30 %) was monitored. Eight male rats, aged 6 weeks, were divided into a control group fed on a normal diet, and an experimental one, provided with the normal diet enriched with 30 % sesame pericarp. A similar experiment was performed with female rats. At the end of the experiment, the prostate and uterus tissues were surgically removed and kept at − 80°C for up to 2 months. Western blotting and quantitative real-time PCR (qRT-PCR) methods were used in order to investigate the levels of receptor proteins and mRNA. Significant increase in the expression of ERβ in prostate and uterus was evident in both methods, while the magnitude of the observed alteration depended on the applied method. No statistically significant change was observed in the expression of ERα in uterus. In prostate, although the increase was more evident when investigated by means of qRT-PCR, the difference in expression of ERα was not statistically significant. In both tissues, a shift of the ratio of ERα:ERβ in favour of ERβ was evident, indicating, according to existing literature, a beneficial effect of the diet provided upon the health status of the organisms. It is suggested that this effect is attributed to the lignans present in the pericarp which exert phyto-oestrogenic activity.

The increase in CVD incidence following the menopause is associated with oestrogen loss. Dietary isoflavones are thought to be cardioprotective via their oestrogenic and oestrogen receptor-independent effects, but evidence to support this role is scarce. Individual variation in response to diet may be considerable and can obscure potential beneficial effects in a sample population; in particular, the response to isoflavone treatment may vary according to genotype and equol-production status. The effects of isoflavone supplementation (50 mg/d) on a range of established and novel biomarkers of CVD, including markers of lipid and glucose metabolism and inflammatory biomarkers, have been investigated in a placebo-controlled 2×8-week randomised cross-over study in 117 healthy post-menopausal women. Responsiveness to isoflavone supplementation according to (1) single nucleotide polymorphisms in a range of key CVD genes, including oestrogen receptor (ER) α and β and (2) equol-production status has been examined. Isoflavones supplementation was found to have no effect on markers of lipids and glucose metabolism. Isoflavones improve C-reactive protein concentrations but do not affect other plasma inflammatory markers. There are no differences in response to isoflavones according to equol-production status. However, differences in HDL-cholesterol and vascular cell adhesion molecule 1 response to isoflavones v. placebo are evident with specific ERβ genotypes. In conclusion, isoflavones have beneficial effects on C-reactive protein, but not other cardiovascular risk markers. However, specific ERβ gene polymorphic subgroups may benefit from isoflavone supplementation.