Nutrikinetics of Isoflavone Metabolites After Fermented Soybean Product (Cheonggukjang) Ingestion in Ovariectomized Mice

Abstract

ScopeCheonggukjang (CGJ) is a soybean‐based quick‐fermented food popular in Korea that contains a variety of biologically active compounds including isoflavones and saponins. Isoflavone bioavailability may be important for the bone health of postmenopausal women; therefore, the aim of this study is to evaluate the influence of fermentation on the isoflavone metabolite nutrikinetic profile after single dose CGJ or unfermented soybean administration in ovariectomized (OVX) and sham mice.Methods and resultsWe identify 34 isoflavone metabolites using UPLC–QTOF‐MS and analyze their nutrikinetics at different time points (0.25, 0.5, 1, 2, 4, 8, 16, and 24 h) to understand their fermentation‐ and OVX‐mediated time‐dependent concentration changes. Nutrikinetics analysis shows that genistein, daidzein, genistein 4′‐sulfate, dihydrodaidzein sulfate, equol 4′‐sulfate, and equol‐7‐glucuronide are present at high concentrations in all groups based on area‐under‐the‐curve analysis. OVX mice appear to show lower isoflavone bioavailability than mice in the sham group. CGJ enhances various isoflavone metabolite bioavailability including genistein, 3‐hydroxygenistein, and equol 7‐glucuronide, compared to the unfermented soybean‐treated group. Among these metabolites, intact isoflavones, 3‐hydroxygenistein, genistein 4′‐sulfate, and equol 7‐glucuronide promote osteoblastogenesis and inhibit osteoclast formation.ConclusionsCGJ has good isoflavone bioavailability and may be beneficial for the bone health of postmenopausal women.

Bioavailability of Isoflavone Metabolites After Korean Fermented Soybean Paste (Doenjang) Ingestion in Estrogen‐Deficient Rats

“…An imbalance of estrogen may be triggered by the bioavailability of nutrients (Lee et al., ; O'Loughlin, & Morris, ). Our previous study confirmed that the bioavailability of isoflavones differed significantly between sham‐operated and ovariectomized (OVX) rats administered the CGJ, which suggested that OVX affected the bioavailability of isoflavones (Lee et al., ). It is also necessary to compare the bioavailability of isoflavones in long‐term fermented soybean foods such as DJ with the results from short‐term fermented soybean foods (CGJ).…”

“…Previous studies confirmed that isoflavones, which are the functional components of soybeans, are converted to aglycones after fermentation, and that such structural changes improve the bioavailability of isoflavones (Chun et al., ; Lee et al., ). This study investigated the bioavailability of isoflavones upon ingesting it in a representative Korean fermented soybean paste produced by long‐term fermentation in OVX rats.…”

“…Although the isoflavone aglycones daidzein, genistein, and glycitein tended to be rapidly absorbed, predicting the t 1/2 value was difficult. In our previous study, isoflavone aglycones after CGJ ingestion were rapidly absorbed and removed (Lee et al., ). These results suggest that the changes in the physical and chemical properties of food such as the food matrix or chemical composition by long‐term fermentation may influence the bioavailability of isoflavones.…”

“…It is well known that fermentation causes a structural change of the isoflavone of soybean, which changes their bioavailability (Lee et al., ). Fermented soybean products, such as Korean doenjang (DJ) and cheonggukjang (CGJ), Japanese natto , Chinese douche , Thai to‐anao , Indian sujache , and Indonesian tempe , are well known throughout the world.…”

“…Natto and CGJ have been linked to reduced bone loss in postmenopausal women; this may be attributable to the high content and variety of isoflavones (Ikeda et al., ; Wu, Lee, Lee, Chae, & Ahn, ). During the soybean fermentation process, isoflavone glycosides are mostly converted to aglycones, which have a higher bioavailability than isoflavone glycosides (Lee et al., ). However, in an experiment with pure isoflavones, a controversial study reported that glycosides had better bioavailability than aglycones (Rufer et al., ).…”