Soy Diet Worsens Heart Disease In Mice Carrying A Genetic Mutation

Main Category: Veterinary
Also Included In: Heart Disease
Article Date: 05 Jan 2006 - 17:00 PST

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Researchers from the University of Colorado have shown that mice carrying a genetic mutation that is linked to altered heart growth and function in humans, have significantly worse heart problems if fed a soy diet, when compared to mice fed a soy-free (milk protein-based) diet. This is the first study to provide evidence that an environmental influence - in this case diet - can affect the heart. It will also force researchers to rethink the diets of their laboratory mice. The results appear in the January 4, 2006 issue of the Journal of Clinical Investigation.

Hypertrophic cardiomyopathy (HCM) is a genetic cardiovascular disease occurring in 1 in 500 individuals, and is characterized by shortness of breath, chest discomfort, and palpitations that may be a sign of life-threatening arrhythmias. While mutations in a number of genes have been linked to HCM, the variety of symptoms experienced by sufferers suggests that other genetic or environmental factors affect disease prognosis.

For years, soy-rich diets have been speculated to protect against heart disease. The biological consequences of a soy-diet have been attributed to the presence of phytoestrogens, which are plant-derived estrogen-like compounds that interact with the estrogen receptor. Leslie Leinwand and colleagues examined male and female mice that overexpressed a mutant form of the alpha myosin heavy chain gene, which is one known cause of HCM in humans. The researchers found significant growth (known as hypertrophy) of the heart of male mice fed a soy-based diet, in comparison to male and female mutant mice fed a soy-free diet.

The authors propose that the difference observed between the sexes is based on the fact that the female mice, who are constantly exposed to naturally circulating levels of estrogen compounds, are less sensitive than males to the change in estrogen level as a result of the soy diet. Interestingly, the authors observed a significant improvement in cardiac growth and function when the animals were switched to a soy-free diet. The new data provide a strong link between soy diet and the progression of cardiac disease, in mice.

In an accompanying commentary, Cathy Hatcher and Craig Basson from Weill Medical College of Cornell University discuss the influence of a soy diet on heart disease and highlight how in the future, researchers using animal models for the study of human disease will have to consider the diet fed to their animals and how it may influence the manifestation of a disease in animals of various genetic backgrounds.

View the PDF of this article at:
the-jci.org/article.php?id=24676

Brooke Grindlinger
press_releases@the-jci.org
Journal of Clinical Investigation
http://www.jci.org

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