Soy diet worsens heart disease in mice

GM WATCH daily
http://www.gmwatch.org
---
As this research was undertaken in the US, it seems highly
probable 
that the soya used was, in fact, GM.
---
Soy diet worsens heart disease in mice
By University of Colorado at Boulder
Jan 4, 2006
http://www.foodconsumer.org/777/8
/Soy_diet_worsens_heart_disease_in_mice_.shtml

Editor's note: We do not know what type of soy the
researchers used for 
their study. Conventional soy and genetically modified soy
may lead to 
different conclusions. Previous studies have found that GM
soy 
increases the death risk in mice.

A University of Colorado at Boulder study has shown the
health of mice 
carrying a genetic mutation for a disease that is the
leading cause of 
sudden cardiac death in people under 30 worsened
considerably when the 
animals were fed a soy-based diet.

Male mice carrying the mutation for hypertrophic
cardiomyopathy, or 
HCM, were severely affected by the soy diet, exhibiting
progressively 
enlarged heart muscles and eventual heart failure, said
CU-Boulder 
Professor Leslie Leinwand. When the mice in the study were
switched to
a diet 
of the milk protein, casein, the condition of the males
improved 
markedly, said Leinwand, chief author of the study.

Female mice carrying the mutation for HCM, which is
characterized by 
the thickening of heart muscle that can obstruct blood flow,
were 
relatively unaffected, she said. The research team
hypothesized that
heart 
deterioration in male mice was due at least in part to
plant-based 
estrogens in the soy food diet that triggered a cascade of
biochemical 
reactions and ultimately increased apoptosis, or programmed
cell
death, in the 
heart.

"We were shocked by the results," said Leinwand,
chair of the 
molecular, cellular and developmental biology department and
chief
study author. 
"This study shows that at least in mice, diet can have
a more profound 
effect on heart disease than any drug that we could
imagine."

A paper on the subject by Leinwand, Dr. Brian Stauffer, a
cardiologist 
at Denver Health Medical Center and the University of
Colorado Health 
Sciences Center, CU-Boulder research associate John Konhilas
and 
doctoral student Elizabeth Luczak appears in the January
issue of the
Journal 
of Clinical Investigation, one of the nation's leading
medical 
journals.

"To our knowledge this is the first report of
significant differences 
in cardiac muscle adaptation due to dietary
manipulation," the 
researchers wrote in JCI.

The CU research team speculated the soy diet affected male
mice more 
severely because the females already had large amounts of
estrogen 
naturally circulating through their bodies, making the
proportional
increase 
in estrogen compounds from the soy diet significantly less,
said 
Leinwand. In addition, male mammals, from mice to humans,
are more
severely 
affected by the symptoms of HCM than females, she said.

The study mice were bred over generations to carry HCM, a
disease which 
causes the heart's lower chambers, or ventricles, to thicken
and 
prevents the heart from fully relaxing between heartbeats,
said
Leinwand. In 
the latter stages of the disease, the heart's ventricle
chamber 
enlarges, the heart wall thins and the pumping contractions
of the
heart are 
impaired, leading to heart failure, she said.

HCM is the leading cause of death in young athletes and
affects about 
one in 500 people, although milder forms of the disease
often go 
undiagnosed, said Leinwand. To date, 18 genes associated
with HCM have
been 
identified and several more are being investigated, she
said.

Soy foods and diet supplements are perceived to be a huge
health 
benefit to humans, as evidenced by the estimated $4.7
billion spent by 
consumers on them in 2005, said Leinwand. "I don't
think normal, healthy 
people should be alarmed by the results of this study,"
said Leinwand.
"But 
we are seeing more cautionary reactions from the medical
community in 
recent years regarding the ingestion of huge quantities of
dietary 
supplements, including soy phytoestrogens."

Leinwand said plant estrogens have been shown to have a
potent effect 
on living organisms. While they are sometimes suggested by
doctors to 
treat menopausal symptoms in women, studies have shown that
common plant 
estrogens like genistein and daidzein can contribute to
reduced 
fertility in farm animals.

"There are some very complex issues in this study that
we don't yet 
fully understand from a biochemical standpoint," she
said. "But the study 
should help lead to a better understanding of how genes and
diet 
interact."

Currently, the main treatment for end-stage HCM is a heart
transplant, 
she said.


The CU-Boulder study was funded by a grant from the Heart,
Lung and 
Blood Institute of the National Institutes of Health and the
American 
Heart Association.

Contact: Leslie Leinwand
leslie.leinwandcolorado.edu
303-492-7606
University of Colorado at Boulder