Dietary phytoestrogens: A possible role in renal disease protection

There is growing evidence that dietary phytoestrogens have a beneficial rol e in chronic renal disease. This review summarizes the recent findings from dietary intervention studies performed in animals and humans suggesting th at consumption of soy-based protein rich in isoflavones and flaxseed rich i n lignans retards the development and progression of chronic renal disease. In several animal models of renal disease, both say protein and flaxseed h ave been shown to limit or reduce proteinuria and renal pathological lesion s associated with progressive renal failure, In studies of human subjects w ith different types of chronic renal disease, soy protein and flaxseed also appear to moderate proteinuria and preserve renal function, However, most of these clinical trials were of relatively short duration and involved a s mall number of patients. Furthermore, it is not clear whether the renal pro tective effects of say protein and flaxseed are caused by the isoflavones ( daidzein and genistein) and lignans (matairesinol and secoisolariciresinol) or some other component. The biochemistry, metabolism, and mechanisms of a ctions of isoflavones and lignans are discussed. Isoflavones and lignans ap pear to act through various mechanisms that modulate cell growth and prolif eration, extracellular matrix synthesis, inflammation, and oxidative stress . Some of these actions have been shown in vitro, but studies of the mechan isms operative in vivo are lacking. The diversity of cellular actions of is oflavones and lignans supports their protective effects in a variety of exp erimental and human types of chronic renal disease. Further investigations are needed to evaluate their long-term effects on renal disease progression in patients with chronic renal failure. (C) 2001 by the National Kidney Fo undation, Inc.