Urinary isoflavonoid phytoestrogen and lignan Excretion After Consumption of Fermented and Unfermented Soy Products

Urinary isoflavonoid excretion is inversely associated with the ratio of protein to dietary fibre intake in young women

“…The mean recovery of total isoflavonoids, expressed as a percentage of supplement dose excreted during 24 h, was 2279%, which is similar to values of 19 and 30% reported in previous studies using supplements derived from red clover (Hodgson et al, 1998;Nestel et al, 1999). Greater recovery was observed with daidzein and related compounds (55723%) compared to those of genistein (7.876.0%), and is consistent with previous findings with isoflavones derived from soy (Kelly al, 1993;Hutchins et al, 1995;Xu et al, 1995;Lu et al, 1996;Tew et al, 1996).…”

“…Equol excretion in women has been associated with a hormonal profile of reduced risk for breast cancer (Duncan et al, 2000). The relatively low prevalence for equol excretors observed in this study is comparable to rates seen in studies with isoflavones derived from soy, where 20-36% of subjects were reported to excrete equol (Kelly et al, 1993;Cassidy et al, 1994;Hutchins et al, 1995;Kirkman et al, 1995;Lampe et al, 1998;Duncan et al, 2000;Rowland et al, 2000).…”

“…Some previous studies have reported a reciprocal relationship between excretion of equol and O-dma (Hutchins et al, 1995;Kelly et al, 1995;Arai et al, 2000) although this was not confirmed in the current study or other studies (Karr et al, 1997;Lampe et al, 1998;Rowland et al, 2000). Interest is focused on equol since this metabolite has greater oestrogenic potency than either daidzein or O-dma and therefore excretor status could have physiological implications.…”

“…A dose-dependent relationship has been reported between intake and mean excretion of isoflavonoids after 9-day treatments with four levels of soy protein (Karr et al, 1997). However, intervention studies with soy products have reported surprisingly wide, largely unexplained variation in the excretion of isoflavonoids between individuals ingesting the same dose (Kelly et al, 1993;Hutchins et al, 1995;Tew et al, 1996;Lampe et al, 1998;Slavin et al, 1998;Rowland et al, 2000). The degree of metabolic conversion of the original plant isoflavones could vary according to differences in the population of the intestinal bacteria involved in the hydrolysis, demethoxylation and reduction of isoflavones.…”

“…The variation could also arise from differences in dietary macronutrient intake, which in turn could selectively modify the growth of intestinal bacteria involved in isoflavonoid transformations, particularly in the production of equol Rowland et al, 2000) where only 20-36% of subjects can produce and excrete this metabolite (Kelly et al, 1993;Cassidy et al, 1994;Hutchins et al, 1995;Kirkman et al, 1995;Lu et al, 1996;Lampe et al, 1998;Lu & Anderson 1998;Duncan et al, 2000;Rowland et al, 2000). Macronutrient composition of the diet could affect bacterial activity by changing the intestinal pH, redox potential or transit time, or influencing the availability of substrates for the bacteria to utilise (Cummings & Macfarlane, 1991).…”