Reported May 04, 2010
Brown or half-milled rice may reduce the risk of heart
disease and high blood pressure by interfering with a protein linked to
those conditions, suggests a new study by researchers at the Cardiovascular
Research Center and Department of Physiology at Temple University School of
The research by Satoru Eguchi, Associate Professor of Physiology, suggests
that a component in a layer of tissue surrounding grains of brown rice may
work against angiotensin II. Angiotensin II is an endocrine protein and a
known culprit in the development of high blood pressure and atherosclerosis.
The findings are contained in a study conducted by Dr. Eguchi and his
colleague at the Temple lab, Akira Takaguri.
Dr. Takaguri will present the team's findings at the annual 2010
Experimental Biology conference in Anaheim, CA on April 24-28.
The subaleurone layer of Japanese rice, which is located between the white
center of the grain and the brown fibrous outer layer, is rich in
oligosaccharides and dietary fibers, making it particularly nutritious.
However, when brown rice is polished to make white rice, the subaleurone
layer is stripped away and the rice loses some of its nutrients. The
subaleurone layer can be preserved in half-milled (Haigamai) rice or
incompletely-milled (Kinmemai) rice. These types of rice are popular in
Japan because many people there believe they are healthier than white rice.
The Temple team and their colleagues at the Wakayama
Medical University Department of Pathology and the Nagaoka National College
of Technology Department of Materials Engineering in Japan sought to delve
into the mysteries of the subaleurone layer and perhaps make a case for
leaving it intact when rice is processed. Because angiotensin II is a
perpetrator in such lethal cardiovascular diseases, the team chose to focus
on learning whether the subaleurone layer could somehow inhibit the wayward
protein before it wreaks havoc.
First, the team removed the subaleurone tissue from Kinmemai rice. Then they
separated the tissue's components by exposing the tissue to extractions of
various chemicals such as ethanol, methanol and ethyl acetate. The team then
observed how the tissue affected cultures of vascular smooth muscle cells.
Vascular smooth muscle cells are an integral part of blood vessel walls and
are direct victims of high blood pressure and atherosclerosis.
During their analysis, the team found that subaleurone components that were
selected by an ethyl acetate extraction inhibited angiotensin II activity in
the cultured vascular smooth muscle cells. This suggests that the
subaleurone layer of rice offers protection against high blood pressure and
atherosclerosis. It could also help explain why fewer people die of
cardiovascular disease in Japan.
"Our research suggests that there is a potential ingredient in rice that may
be a good starting point for looking into preventive medicine for
cardiovascular diseases," said Dr. Eguchi. "We hope to present an additional
health benefit of consuming half-milled or brown rice [as opposed to white
rice] as part of a regular diet."
Source : timesofindia.indiatimes.com