Soy isoflavones in nutritionally relevant amounts have varied nutrigenomic effects on adipose tissue

Abstract

Soy consumption has been suggested to afford protection from cardiovascular disease (CVD). Indeed, accumulated albeit controversial evidence suggests that daily consumption of ≥25 g of soy protein with its associated phytochemicals intact can improve lipid profiles in hypercholesterolemic humans. However, the belief that soy foods and supplements positively impact human health has become increasingly controversial among the general public because of the reported estrogenic activities of soy isoflavones. In this study, we investigated the nutrigenomic actions of soy isoflavones (in nutritionally-relevant amounts) with a specific focus on the adipose tissue, due to its pivotal role in cardiometabolism. Young C57BL/6 mice were maintained for eight weeks under two different diet regimes: (1) purified control diet; or (2) purified control diet supplemented with 0.45 g% soybean dry purified extract (a genistein/daidzein mix). Soy isoflavones increased plasma total cholesterol concentrations and decreased triglyceride ones. Circulating leptin levels was also increased by soy consumption. Differentially expressed genes in adipose tissue were classified according to their role(s) in cellular or metabolic pathways. Our data show that soy isoflavones, administered in nutritionally-relevant amounts, have diverse nutrigenomic effects on adipose tissue. Taking into account the moderate average exposure to such molecules, their impact on cardiovascular health needs to be further investigated to resolve the issue of whether soy consumption does indeed increase or decrease cardiovascular risk.

Figure 1

Leptin circulating concentrations in mice receiving either chow diet (control) or 0.45% Soyselect^® during eight weeks (n = 7 per group). * p < 0.05 as compared with controls.

Figure 2

Venn diagram of selected pathway analyses. Pathway analyses of Soyselect^®-modulated genes were performed and MAPK, TGFβ, and chemokine signaling were included as examples.

Figure 3

RT-qPCR validation of selected genes related to MAPK, TGFβ, chemokine signaling, and others related to lipid metabolism. Mice received either chow diet (ctrl) or 0.45% Soyselect^® during eight weeks. mRNA is given as relative expression (n = 6 per group). * p < 0.05 as compared with controls.