FDA Logo link U.S. Food and Drug AdministrationNational Center for Toxicological Research
U.S. Department of Health and Human Services
horizonal rule
Image of the NCTR Regulatory Research Perspectives page banner

Subscribe to the Regulatory Research Perspectives e-mail list.

Current Issue:

July 2007, Volume 7, Issue 1: "Studies on the Influence of Dietary Isoflavones, Daidzein and Genistein, in Chemical Mutagenesis and Tumor Development in Female Rats"

Text Version, PDF Version, Past Issues

Issue 1 of Volume 7 of the Regulatory Research Perspectives: Impact on Public Health.

Introduction Paragraph for current issue:

Hormone replacement therapy (HRT) in women has been shown to confer several benefits, including a reduction of hot flashes during menopause. However, HRT has also been linked to increased risks for heart attack, stroke, and breast cancer. To avoid the potentially harmful side effects of HRT, many women are switching to alternative sources of estrogens, such as the isoflavone phytoestrogens, in the belief that naturally occurring substances may be safer than HRT. There is a large body of compelling evidence showing the health benefits of isoflavones. Our Western lifestyle does not normally permit the consumption of soy foods adequate to meet health needs. Thus, many women ingest dietary supplements of phytoestrogens on a regular basis to forestall the complications of menopause. Two of the most commonly ingested isoflavones are daidzein (DZ) and genistein (GE). Both are major components of soy isoflavones and are presumed to be responsible for their health-promoting effects.

It is possible that these compounds may also be toxic. In theory, the naturally occurring isoflavones can alter the metabolism of endogenous hormones and, thus, influence the pathogenesis of hormone-dependent cancers. Early studies have shown that both DZ and GE are mutagenic, indicating that isoflavones may play some role in tumor mutagenesis. The present study examines the mutagenic activity in the whole animal of the carcinogen 7, 12-dimethylbenz(α)anthracene (DMBA). The sensitive Big Blue (BB) mice and rats were used to detect mutations in several organs. In addition, the BB rats were ovariectomized to model menopause. The effects of feeding DZ, GE, and 17β-estradiol on the genotoxicity and tumorigenicity of DMBA in estrogen-responsive tissues were determined. The results help provide a basis for future risk assessment strategies for phytoestrogens.

The objective of the Regulatory Research Perspectives journal is to provide a vehicle for FDA scientists to communicate important scientific information to each other with the hope of generating collaborations and to communicate to the global community science that is important to the Agency. It is hoped that each center will submit manuscripts for publication through their respective editorial board members. See the "Instructions to Authors" provided on this site.

Some of these documents are in Portable Document Format to retain the original format.  To view or print these documents, you must use the Adobe Acrobat viewer.  Acrobat is free and available directly from Adobe's website with full installation instructions.

Get Adobe Acrobat

Past Issues

Date Title Text
March 2006 Technical Issues Involved in Obtaining Reliable Data from Microarray Experiments text version pdf version
March 2005 Application of a Systems Biology/Systems Toxicology Approach to Developmental Neurotoxicology text version pdf version
April 2004 Influence of Body Weight, Diet, and Stress on Aging, Survival and Pathological Endpoints in Rodents: Implications for Toxicity Testing and Risk Assessment text version pdf version
January 2003 On the Chemical Causation of Methyl Deficiency and its Attendant Pathologies text version pdf version
May 2002 Development of Quantitative Structure-Activity Relationships (QSARs) and Their Use for Priority Setting in the Testing Strategy of Endocrine Disruptors text version pdf version
November 2001 Developing Methods of Genetic Analysis to Improve Cancer Risk Assessment text version pdf version
July 2001 Human Health Impact and Regulatory Issues Involving Antimicrobial Resistance in the Food Animal Production Environment text version pdf version


horizonal rule