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Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment.

ABSTRACT: 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.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.Median plasma total isoflavone concentrations after the soy food and supplement interventions were respectively 2.16 and 3.47??mol/l for equol producers and 1.30 and 2.39??mol/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%.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.

SUBMITTER: van der Velpen V

PROVIDER: S-EPMC4197455 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment.

van der Velpen V V Hollman P C PC van Nielen M M Schouten E G EG Mensink M M Van't Veer P P Geelen A A

European journal of clinical nutrition 20140618 10

<h4>Background/objectives</h4>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.<h4>Subjects/methods</h4>Plasma samples were collected from ...[more]

PMID: 24939433

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Project description:High-throughput sequencing of the B cell receptor (BCR) repertoire can provide rapid characterization of the B cell response in a wide variety of applications in health, after vaccination and in infectious, inflammatory and immune-driven disease, and is starting to yield clinical applications. However, the interpretation of repertoire data is compromised by a lack of studies to assess the intra and inter-individual variation in the BCR repertoire over time in healthy individuals. We applied a standardized isotype-specific BCR repertoire deep sequencing protocol to a single highly sampled participant, and then evaluated the method in 9 further participants to comprehensively describe such variation. We assessed total repertoire metrics of mutation, diversity, VJ gene usage and isotype subclass usage as well as tracking specific BCR sequence clusters. There was good assay reproducibility (both in PCR amplification and biological replicates), but we detected striking fluctuations in the repertoire over time that we hypothesize may be due to subclinical immune activation. Repertoire properties were unique for each individual, which could partly be explained by a decrease in IgG2 with age, and genetic differences at the immunoglobulin locus. There was a small repertoire of public clusters (0.5, 0.3, and 1.4% of total IgA, IgG, and IgM clusters, respectively), which was enriched for expanded clusters containing sequences with suspected specificity toward antigens that should have been historically encountered by all participants through prior immunization or infection. We thus provide baseline BCR repertoire information that can be used to inform future study design, and aid in interpretation of results from these studies. Furthermore, our results indicate that BCR repertoire studies could be used to track changes in the public repertoire in and between populations that might relate to population immunity against infectious diseases, and identify the characteristics of inflammatory and immunological diseases.

Dataset Information

Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment.

Publications

Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment.

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