The Isoflavones Genistein and Daidzein Increase Hepatic Concentration of Thyroid Hormones and Affect Cholesterol Metabolism in Middle-Aged Male Rats.

•We examined whether isoflavones increase hepatic thyroid hormone concentrations and affect cholesterol metabolism in rats.•Serum T3 was not affected while hepatic T3 was almost doubled, which supports increased local T3 availability.•Obtained results are compatible with displacement of TH from TTR, major transport protein in rodent blood and human CSF.•Hepatic increase of T3 correlated with up-regulated expression of the Cyp7a1 gene and elevated 7α-hydroxycholesterol.•If also lowered 24-hydroxycholesterol and desmosterol in liver and serum, while the total cholesterol levels remained unchanged.