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Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment.
Eur J Clin Nutr 2014; 68(10):1141-7EJ

Abstract

BACKGROUND/OBJECTIVES

Isoflavones are present in soy foods and soy-based supplements. Despite low plasma isoflavone concentrations in the general Western population, concentrations in supplement users exceed those suggested to be beneficial for health in Asian populations, raising concerns for adverse effects. To aid risk assessment, quantification of the relation between isoflavone intake and plasma concentrations is essential.

SUBJECTS/METHODS

Plasma samples were collected from postmenopausal women in three placebo-controlled crossover studies with 8-week periods for supplements (two studies, ~100 mg isoflavones/day, n=88) or 4-week periods for soy foods (one study, ~48 mg isoflavones/day, n=15). Plasma isoflavone concentrations (daidzein, equol, genistein and glycitein) were quantified using high-performance liquid chromatography and electrochemical detection. The association between plasma concentrations and isoflavone intake, equol producer status, intake-producer interaction and background dietary intake was assessed based on the assumption of a log-linear relation.

RESULTS

Median plasma total isoflavone concentrations after the soy food and supplement interventions were respectively 2.16 and 3.47 μmol/l for equol producers and 1.30 and 2.39 μmol/l for non-producers. Regression analysis showed that doubling isoflavone intake increased plasma concentrations by 55-62% (±s.e. 1-2%, R(2)>0.87) for daidzein, genistein, equol (only for producers) and total isoflavones; for glycitein the association was weaker (15±1%, R(2)=0.48). Adjustments for energy, carbohydrate and fat intake did not affect these estimates. Inter-individual variation, estimated based on repeated measures in one of the studies, was 30-96%.

CONCLUSIONS

Although the relation between isoflavone intake and plasma concentrations was adequately quantified, the use of isoflavone intake data for risk assessment needs caution due to large inter-individual variation in plasma concentrations.

Authors+Show Affiliations

Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.1] Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands [2] RIKILT, Wageningen University & Research Centre, Wageningen, The Netherlands.Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.

Pub Type(s)

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

Language

eng

PubMed ID

24939433

Citation

van der Velpen, V, et al. "Large Inter-individual Variation in Isoflavone Plasma Concentration Limits Use of Isoflavone Intake Data for Risk Assessment." European Journal of Clinical Nutrition, vol. 68, no. 10, 2014, pp. 1141-7.
van der Velpen V, Hollman PC, van Nielen M, et al. Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment. Eur J Clin Nutr. 2014;68(10):1141-7.
van der Velpen, V., Hollman, P. C., van Nielen, M., Schouten, E. G., Mensink, M., Van't Veer, P., & Geelen, A. (2014). Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment. European Journal of Clinical Nutrition, 68(10), pp. 1141-7. doi:10.1038/ejcn.2014.108.
van der Velpen V, et al. Large Inter-individual Variation in Isoflavone Plasma Concentration Limits Use of Isoflavone Intake Data for Risk Assessment. Eur J Clin Nutr. 2014;68(10):1141-7. PubMed PMID: 24939433.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment. AU - van der Velpen,V, AU - Hollman,P C, AU - van Nielen,M, AU - Schouten,E G, AU - Mensink,M, AU - Van't Veer,P, AU - Geelen,A, Y1 - 2014/06/18/ PY - 2013/12/17/received PY - 2014/04/04/revised PY - 2014/04/23/accepted PY - 2014/6/19/entrez PY - 2014/6/19/pubmed PY - 2015/7/23/medline SP - 1141 EP - 7 JF - European journal of clinical nutrition JO - Eur J Clin Nutr VL - 68 IS - 10 N2 - BACKGROUND/OBJECTIVES: Isoflavones are present in soy foods and soy-based supplements. Despite low plasma isoflavone concentrations in the general Western population, concentrations in supplement users exceed those suggested to be beneficial for health in Asian populations, raising concerns for adverse effects. To aid risk assessment, quantification of the relation between isoflavone intake and plasma concentrations is essential. SUBJECTS/METHODS: Plasma samples were collected from postmenopausal women in three placebo-controlled crossover studies with 8-week periods for supplements (two studies, ~100 mg isoflavones/day, n=88) or 4-week periods for soy foods (one study, ~48 mg isoflavones/day, n=15). Plasma isoflavone concentrations (daidzein, equol, genistein and glycitein) were quantified using high-performance liquid chromatography and electrochemical detection. The association between plasma concentrations and isoflavone intake, equol producer status, intake-producer interaction and background dietary intake was assessed based on the assumption of a log-linear relation. RESULTS: Median plasma total isoflavone concentrations after the soy food and supplement interventions were respectively 2.16 and 3.47 μmol/l for equol producers and 1.30 and 2.39 μmol/l for non-producers. Regression analysis showed that doubling isoflavone intake increased plasma concentrations by 55-62% (±s.e. 1-2%, R(2)>0.87) for daidzein, genistein, equol (only for producers) and total isoflavones; for glycitein the association was weaker (15±1%, R(2)=0.48). Adjustments for energy, carbohydrate and fat intake did not affect these estimates. Inter-individual variation, estimated based on repeated measures in one of the studies, was 30-96%. CONCLUSIONS: Although the relation between isoflavone intake and plasma concentrations was adequately quantified, the use of isoflavone intake data for risk assessment needs caution due to large inter-individual variation in plasma concentrations. SN - 1476-5640 UR - https://www.unboundmedicine.com/medline/citation/24939433/Large_inter_individual_variation_in_isoflavone_plasma_concentration_limits_use_of_isoflavone_intake_data_for_risk_assessment_ L2 - http://dx.doi.org/10.1038/ejcn.2014.108 DB - PRIME DP - Unbound Medicine ER -