Phytoestrogens: Friend or foe?
Phytoestrogens: Friend or foe?
Year: 1996
Authors: J Barrett.
Publication Name: Environ. Health Perspect.
Publication Details: Volume 104; Number 5; 478.
Abstract:
In this review paper, the author describes the role of phytoestrogens in the prevention of diseases common in populations consuming a Western style diet with particular focus upon breast, colon and prostate cancer. The article focuses upon lignans found in flaxseed and isoflavonoids found in soy products. The author interviews a number of scientists who have been involved in various research activities related to the health effects of phytoestrogens. Plasma levels of phytoestrogens have been reported to be high in populations living in areas with low rates of several diseases including coronary heart disease and cancer. The metabolism of these compounds is described in this article. Plant lignans and isoflavonoids are converted in the lower gut in humans into hormone-like compounds that influence sex hormone production, metabolism and biological activity. In vitro studies have shown that phytoestrogens can elicit both estrogenic and anti-estrogenic effects and may inhibit cell cancer growth. Research has also demonstrated anti-carcinogenic effects of phytoestrogens that are not associated with estrogenicity including inhibition of enzymes such as aromatase and stimulation of sex hormone binding globulin, both of which affect the levels of free steroidal hormones in the body. In vivo studies have shown that genistein and secoisolariciresinol diglycoside are cytotoxic to some forms of cancer. In human studies, isoflavones and lignans have been demonstrated to induce changes in the menstrual cycle. Many studies conducted in humans for phytoestrogenic effects, however, have been confounded by uncontrollable variables including genetics, types and levels of intestinal flora, diet, health and hormonal status. Researchers have indicated that longer term prospective studies on the health effects of phytoestrogens are required. In addition, more information is necessary regarding possible interactions of phytoestrogens with traditional estrogen replacement therapy or cancer therapies.
