Urinary Isoflavones Are Increased in Adults, But Decreased in Children, Consuming Soy When on Oral Antibiotic Therapy

Abstract

The goal of this study was to evaluate how oral antibiotics (OABX) change the appearance of isoflavones (IFLs) in adults and children after soy consumption. The urinary IFL excretion rate (UIER) known to reflect circulating IFLs was hypothesized to change due to intestinal microflora changes by OABX. Subjects provided urine collections in pairs of a baseline urine and an overnight urine before and after consuming soy nuts first during OABX treatment and then again when healthy. During OABX versus when healthy, UIER (nmol/h/kg) in adults (n = 12) was increased (P < 0.05) for daidzein (35.2 ± 7.2 vs. 18.9 ± 2.4), daidzein + genistein + glycitein [nonmetabolites (NM); 42.6 ± 8.0 vs. 23.6 ± 2.9), and total isoflavonoids (Total IFLs; daidzein + genistein + glycitein + dihydrodaidzein + dihydrogenistein + equol + O-desmethylangolensin) (51.5 ± 10.3 versus 29.6 ± 4.7). In contrast, children (n = 7) showed reduced UIER (P < 0.05) when on OABX versus when healthy for daidzein (36.3 ± 6.4 vs. 46.8 ± 4.7), dihydrodaidzein (1.2 ± 0.6 vs. 3.0 ±1.1), NM (46.3 ± 8.2 vs. 59.5 ± 6.0), dihydrodaidzein + dihydrogenistein + equol + O-desmethylangolensin (1.0 ± 0.8 vs. 4.3 ± 1.3), and Total IFLs (48.2 ± 8.5 vs. 63.8 ± 6.4).

ACKNOWLEDGMENTS

Supported in part by the Revival Company and the National Cancer Institute CCSG CA71789. We thank Laurie Custer, BS, for performing the chemical analyses. Support from Revival Company, Kernersville, North Carolina, and DrSoy Nutrition, Irvine, California, for this research is acknowledged. Adrian A. Franke, PhD, the principal investigator of this study, was responsible for the design and overall performance of the study; he carried out data interpretation, statistical analyses, and wrote the manuscript. Brunhild M. Halm, MD, PhD, assisted in the design and overall performance of the study, recruited study participants, supervised personnel, conducted data interpretations, and made major contributions in writing the manuscript. Leslie A. Ashburn, MA, was a study coordinator and assisted in manuscript preparation, statistical analyses, as well as matters related to the institutional review board. No authors have a conflict of interest.

Notes

^a Means ± SD are shown. Abbreviations are as follows: BW, body weight; OABX, oral antibiotics; ONU, overnight urine.

^a 12 subjects, oral antibiotics.

^b Repeated treatment of subject 4 in the sequence shown.

^a 7 subjects, oral antibiotics.

^b Repeated treatment of subject 7 in the sequence shown.

^a Abbreviations are as follows: UIER, urinary isoflavone (IFL) excretion rate; DE, daidzein; GE, genistein; GLYE, glycitein; EQ, equol; DMA, desmethylangolensin; DHDE, dihydrodaidzein; DHGE, dihydrogenistein; NM, nonmetabolites; M, metabolites; Total IFLs, sum of all isoflavonoids tested. P = significance of difference between adults and children by unpaired t-test.