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Optimal cut-off value for equol-producing status in women: The Japan Nurses' Health Study urinary isoflavone concentration survey.
PLoS One. 2018; 13(7):e0201318.Plos

Abstract

Equol is one of the most active soy isoflavones. When the association between soy food intake in daily life and health outcomes is examined in epidemiological studies, it is important to define the equol-producing status of each individual. However, few studies have assessed equol-producing status without a soy challenge test. To determine a robust cutoff criterion for equol producer classification in observational studies, we conducted a urinary isoflavone concentration survey in daily life among women. Furthermore, we examined the association between eating habits regarding soy foods and equol-producing status. A total of 4,412 participants were included in the analyses. Urinary isoflavones were analyzed using a high-performance liquid chromatography method. We examined the distribution of the log10 equol/daidzein ratios, finding a mixture of two normal distributions, corresponding to equol producer and non-producer subpopulations. Applying a finite mixture model, we estimated the means, standard deviations, and mixing proportions of these two distributions. The estimation was carried out using the SAS NLIN procedure. The optimal cutoff point for the log10 equol/daidzein ratio in the study population was determined to be -1.42, according to the estimated parameters of the mixture distribution. Based on this criterion, 1,830 (41.5%) of the participants were identified as equol producers. Compared with non-consumers of soy foods, consumers of soy foods had significantly higher odds of being equol producers. Using log10-transformed equol/daidzein ratios ≥ -1.42 to define equol producers among Japanese women is reasonable and suitable for determining equol-producing status in epidemiological studies. We found that soy food eating habits were associated with equol-producing status. Further investigation is required to evaluate associations between equol-producing status in daily life and health outcomes. The results of this study suggest the best cutoff point to use in the definition of equol-producing status in daily life.

Authors+Show Affiliations

Gunma University Initiative for Advanced Research, Maebashi City, Gunma, Japan.Graduate School of Health Science, Gunma University, Maebashi City, Gunma, Japan.Graduate School of Health Science, Gunma University, Maebashi City, Gunma, Japan.Graduate School of Health Science, Gunma University, Maebashi City, Gunma, Japan.Center for Medical Education, Gunma University, Maebashi City, Gunma, Japan.Saga Nutraceuticals Research Institute, Otsuka Pharmaceutical Co., Ltd. Kanzaki-gun, Saga, Japan.Saga Nutraceuticals Research Institute, Otsuka Pharmaceutical Co., Ltd. Kanzaki-gun, Saga, Japan.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

30048499

Citation

Ideno, Yuki, et al. "Optimal Cut-off Value for Equol-producing Status in Women: the Japan Nurses' Health Study Urinary Isoflavone Concentration Survey." PloS One, vol. 13, no. 7, 2018, pp. e0201318.
Ideno Y, Hayashi K, Nakajima-Shimada J, et al. Optimal cut-off value for equol-producing status in women: The Japan Nurses' Health Study urinary isoflavone concentration survey. PLoS One. 2018;13(7):e0201318.
Ideno, Y., Hayashi, K., Nakajima-Shimada, J., Onizuka, Y., Kishi, M., Ueno, T., & Uchiyama, S. (2018). Optimal cut-off value for equol-producing status in women: The Japan Nurses' Health Study urinary isoflavone concentration survey. PloS One, 13(7), e0201318. https://doi.org/10.1371/journal.pone.0201318
Ideno Y, et al. Optimal Cut-off Value for Equol-producing Status in Women: the Japan Nurses' Health Study Urinary Isoflavone Concentration Survey. PLoS One. 2018;13(7):e0201318. PubMed PMID: 30048499.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Optimal cut-off value for equol-producing status in women: The Japan Nurses' Health Study urinary isoflavone concentration survey. AU - Ideno,Yuki, AU - Hayashi,Kunihiko, AU - Nakajima-Shimada,Junko, AU - Onizuka,Yoko, AU - Kishi,Mikiko, AU - Ueno,Tomomi, AU - Uchiyama,Shigeto, Y1 - 2018/07/26/ PY - 2018/04/10/received PY - 2018/07/12/accepted PY - 2018/7/27/entrez PY - 2018/7/27/pubmed PY - 2019/1/18/medline SP - e0201318 EP - e0201318 JF - PloS one JO - PLoS One VL - 13 IS - 7 N2 - Equol is one of the most active soy isoflavones. When the association between soy food intake in daily life and health outcomes is examined in epidemiological studies, it is important to define the equol-producing status of each individual. However, few studies have assessed equol-producing status without a soy challenge test. To determine a robust cutoff criterion for equol producer classification in observational studies, we conducted a urinary isoflavone concentration survey in daily life among women. Furthermore, we examined the association between eating habits regarding soy foods and equol-producing status. A total of 4,412 participants were included in the analyses. Urinary isoflavones were analyzed using a high-performance liquid chromatography method. We examined the distribution of the log10 equol/daidzein ratios, finding a mixture of two normal distributions, corresponding to equol producer and non-producer subpopulations. Applying a finite mixture model, we estimated the means, standard deviations, and mixing proportions of these two distributions. The estimation was carried out using the SAS NLIN procedure. The optimal cutoff point for the log10 equol/daidzein ratio in the study population was determined to be -1.42, according to the estimated parameters of the mixture distribution. Based on this criterion, 1,830 (41.5%) of the participants were identified as equol producers. Compared with non-consumers of soy foods, consumers of soy foods had significantly higher odds of being equol producers. Using log10-transformed equol/daidzein ratios ≥ -1.42 to define equol producers among Japanese women is reasonable and suitable for determining equol-producing status in epidemiological studies. We found that soy food eating habits were associated with equol-producing status. Further investigation is required to evaluate associations between equol-producing status in daily life and health outcomes. The results of this study suggest the best cutoff point to use in the definition of equol-producing status in daily life. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/30048499/Optimal_cut_off_value_for_equol_producing_status_in_women:_The_Japan_Nurses'_Health_Study_urinary_isoflavone_concentration_survey_ L2 - https://dx.plos.org/10.1371/journal.pone.0201318 DB - PRIME DP - Unbound Medicine ER -