Validation of ELISAs for Isoflavones and Enterolactone for Phytoestrogen Intake Assessment in the French Population

Abstract

Phytoestrogens are dietary compounds with low estrogenic activity. The two main categories in the French diet are isoflavones from pulses and enterolignans metabolized by the gut flora from various lignans found in fruits, vegetables, grains, and beverages. Isoflavones and lignans have different effects on human physiology and can antagonize each other. Comprehensive lists of phytoestrogen sources were constructed based on measurements and literature data. The 24 h and 48 h dietary recalls were proposed to the volunteers of the ISOLED cohort (NCT03421184). Urine and plasma samples from these volunteers were assayed for genistein, daidzein, equol, and enterolactone. A dietary score was constructed considering the pharmacokinetic characteristics of these compounds. Correlation analyses were applied to fluid concentrations associated with dietary scores. Pearson correlations reached 0.921 (p < 0.001) for urineIF, 0.900 (p < 0.001) for plasmaIF, 0.764 (p < 0.001) for urineENL, and 0.723 (p < 0.001) for plasmaENL. ELISAs associated with careful intake assessments proved to be good tools for phytoestrogens’ exposure estimation.

Advances in the Metabolic Mechanism and Functional Characteristics of Equol

“…However, since equol is not sensitive to ultraviolet absorption, the repeatability of the ultraviolet detection method is not high to a certain extent. Immunoassay is a highly sensitive method for equol detection, which can not only be applied to a large number of samples, but can also analyze low concentrations of soy isoflavone metabolites in complex samples [ 130 ]. Among them, fluorescent immunoassay (FIA) has advantages over radioimmunoassay (RIA) for non-radioisotope assays, such as stability, no radiation, and no waste problems, so it can be applied to routine detection work.…”

Traditional and Domestic Cooking Dramatically Reduce Estrogenic Isoflavones in Soy Foods

“…Nevertheless, data obtained using ELISA appeared reliable and comparable to the best chromatographic techniques challenged in this trial when aglycone forms were considered. Additionally, ELISAs have been validated in two studies designed to test food-frequency questionnaires assessing recent [22] and usual soy intakes [21]. To date, there is no legal technique for isoflavones determination in France.…”