Association between equol production and metabolic syndrome in Japanese women in their 50s-60s

Exploring functional genes' correlation with (S)-equol concentration and new daidzein racemase identification

With its estrogenic activity, (S)-equol plays an important role in maintaining host health and preventing estrogen-related diseases. Exclusive production occurs through the transformation of soy isoflavones by intestinal bacteria, but the reasons for variations in (S)-equol production among different individuals and species remain unclear. Here, fecal samples from humans, pigs, chickens, mice, and rats were used as research objects. The concentrations of (S)-equol, along with the genetic homology and evolutionary relationships of (S)-equol production-related genes [daidzein reductase (DZNR), daidzein racemase (DDRC), dihydrodaidzein reductase (DHDR), tetrahydrodaidzein reductase (THDR)], were analyzed. Additionally, in vitro functional verification of the newly identified DDRC gene was conducted. It was found that approximately 40% of human samples contained (S)-equol, whereas 100% of samples from other species contained (S)-equol. However, there were significant variations in (S)-equol content among the different species: rats > pigs > chickens > mice > humans. The distributions of the four genes displayed species-specific patterns. High detection rates across various species were exhibited by DHDR, THDR, and DDRC. In contrast, substantial variations in detection rates among different species and individuals were observed with respect to DZNR. It appears that various types of DZNR may be associated with different concentrations of (S)-equol, which potentially correspond to the regulatory role during (S)-equol synthesis. This enhances our understanding of individual variations in (S)-equol production and their connection with functional genes in vitro. Moreover, the newly identified DDRC exhibits higher potential for (S)-equol synthesis compared to the known DDRC, providing valuable resources for advancing in vitro (S)-equol production.

IMPORTANCE

(S)-equol ((S)-EQ) plays a crucial role in maintaining human health, along with its known capacity to prevent and treat various diseases, including cardiovascular diseases, metabolic syndromes, osteoporosis, diabetes, brain-related diseases, high blood pressure, hyperlipidemia, obesity, and inflammation. However, factors affecting individual variations in (S)-EQ production and the underlying regulatory mechanisms remain elusive. This study examines the association between functional genes and (S)-EQ production, highlighting a potential correlation between the DZNR gene and (S)-EQ content. Various types of DZNR may be linked to the regulation of (S)-EQ synthesis. Furthermore, the identification of a new DDRC gene offers promising prospects for enhancing in vitro (S)-EQ production.

Exploring substrate-microbe interactions: a metabiotic approach toward developing targeted synbiotic compositions

Gut microbiota is an important modulator of human health and contributes to high inter-individual variation in response to food and pharmaceutical ingredients. The clinical outcomes of interventions with prebiotics, probiotics, and synbiotics have been mixed and often unpredictable, arguing for novel approaches for developing microbiome-targeted therapeutics. Here, we review how the gut microbiota determines the fate of and individual responses to dietary and xenobiotic compounds via its immense metabolic potential. We highlight that microbial metabolites play a crucial role as targetable mediators in the microbiota-host health relationship. With this in mind, we expand the concept of synbiotics beyond prebiotics' role in facilitating growth and engraftment of probiotics, by focusing on microbial metabolism as a vital mode of action thereof. Consequently, we discuss synbiotic compositions that enable the guided metabolism of dietary or co-formulated ingredients by specific microbes leading to target molecules with beneficial functions. A workflow to develop novel synbiotics is presented, including the selection of promising target metabolites (e.g. equol, urolithin A, spermidine, indole-3 derivatives), identification of suitable substrates and producer strains applying bioinformatic tools, gut models, and eventually human trials.In conclusion, we propose that discovering and enabling specific substrate-microbe interactions is a valuable strategy to rationally design synbiotics that could establish a new category of hybrid nutra-/pharmaceuticals.

Association between equol and non-alcoholic fatty liver disease in Japanese women in their 50s and 60s

BACKGROUND AND AIM

Equol is a metabolite of soy isoflavone and has estrogenic activity. The incidence of non-alcoholic fatty liver disease (NAFLD) increases after menopause in women, which is thought to result in a decrease in estrogen. This study aimed to evaluate the association between equol and NAFLD.

METHODS

We evaluated 1185 women aged 50-69 years who underwent health check-ups at four health centers in Fukushima, Japan. Equol producers were defined by a urinary equol concentration of 1.0 μM or more. In addition to comparison between equol producers and non-producers, the association between equol and NAFLD was estimated using logistic regression analysis adjusting for fast walking and eating habits.

RESULTS

Of the 1185 participants, 345 (29.1%) women were equol producers. The proportions of women who had NAFLD (34.8% vs 45.2%) were significantly lower in the equol-producing group than in the non-producing group. Multivariable logistic regression analysis showed that equol production was significantly associated with NAFLD (odds ratio = 0.66, 95% confidence interval: 0.51-0.86).

CONCLUSIONS

Equol production was significantly associated with NAFLD in women in their 50s and 60s.

Frequency of Phytoestrogen Consumption and Symptoms at Midlife among Bangladeshis in Bangladesh and London

There is a longstanding interest in the relationship between diet and hot flash symptoms during midlife, especially in whether phytoestrogens ease menopausal symptoms. The purpose of this study was to examine hot flashes, night sweats, trouble sleeping, and vaginal dryness in relation to the intake of foods rich in phytoestrogens among Bangladeshi women aged 35 to 59 years who were living either in Sylhet, Bangladesh (n = 157) or as migrants in London (n = 174). Consumption ranges for phytoestrogens were constructed from food frequencies. We hypothesized that diets rich in isoflavones, lignans, and coumestrol would be associated with lower symptom frequencies. However, adjusted logistic regression results showed that with each incremental increase in general phytoestrogen consumption (scale of 0 to 10), the likelihood of hot flashes increased by 1.4%. Each incremental increase in lignan consumption raised the likelihood of hot flashes by 1.6%. In contrast, the odds of vaginal dryness decreased by 2%, with each incremental increase in phytoestrogen and lignan consumption, and by 4%, with each incremental increase in isoflavone consumption. Night sweats and trouble sleeping were not associated with phytoestrogen intake in logistic regressions. Our findings add to the conflicting data on relationships between phytoestrogens and symptoms associated with menopause.

Urinary phytoestrogens and the risk of uterine leiomyomata in US women

BACKGROUND

Uterine leiomyomata (UL) is a common gynecological disease in women. Studied on the relationship between single metabolites of urinary phytoestrogens and UL, especially for the combined effects of mixed metabolites on UL still are insufficient.

METHODS

In this cross-sectional study, we included 1,579 participants from the National Health and Nutrition Examination Survey. Urinary phytoestrogens were assessed by measuring urinary excretion of daidzein, genistein, equol, O-desmethylangolensin, enterodiol and enterolactone. The outcome was defined as UL. Weighted logistic regression was used to analyze the association between single metabolites of urinary phytoestrogens and UL. Notably, we adopted the weighted quantile sum (WQS) regression, Bayesian kernel machine regression (BKMR), and quantile g-computation (qgcomp) models, to investigate the combined effects of six mixed metabolites on UL.

RESULTS

The prevalence of UL was approximately 12.92%. After adjusting age, race/ethnicity, marital status, drinking status, body mass index, waist circumference, menopausal status, ovary removed status, use of female hormones, hormones/hormone modifiers, total energy, daidzein, genistein, O-desmethylangolensin, enterodiol, and enterolactone, the association of equol with UL was significant [Odds ratio (OR) = 1.92, 95% confidence interval (CI): 1.09-3.38]. In the WQS model, mixed metabolites of urinary phytoestrogen had a positive association with UL (OR = 1.68, 95%CI: 1.12-2.51), with the highest weighted chemical of equol. In the gpcomp model, equol had the largest positive weight, followed by genistein and enterodiol. In the BKMR model, equol and enterodiol have positive correlation on UL risk, while enterolactone has negative correlation.

CONCLUSION

Our results implied a positive association between the mixed metabolites of urinary phytoestrogen and UL. This study provides evidence that urinary phytoestrogen-metabolite mixture was closely related to the risk of female UL.