LOS ANGELES (January 3, 2000) – Increased blood levels of phytoestrogens -- plant estrogens found in such foods as soybeans, chickpeas and other beans -- are linked to beneficial cholesterol levels and better arterial function in women, according to results of a major, nationwide study presented by Cedars-Sinai Medical Center cardiologist C. Noel Bairey Merz at the American Heart Association's annual meeting in November.
These findings could prove significant in reducing risk factors associated with heart disease in women. Sponsored by the National Institutes of Health’s National Heart, Lung and Blood Institute (NHLBI), the Women’s Ischemia Syndrome Evaluation (WISE) is a multifaceted four-year, four-center study of 1,000 women with the main objective of developing better techniques for diagnosing heart disease in women. Dr. Bairey Merz serves as scientific chair for the $8-10 million study, conducted at Cedars-Sinai, University of Florida, University of Alabama, University of Pittsburgh and Allegheny General Hospital.
"Now in its fourth and final year, the study is filling a big vacuum in information regarding women and heart disease," explains Dr. Bairey Merz, director of the Preventive and Rehabilitative Cardiac Center, Cedar-Sinai, and associate professor of clinical medicine, University of California-Los Angeles. "WISE is the first funded study of its kind to measure the level of phytoestrogens in women’s blood and make a correlation between this data and heart disease."
One phase of the study looked at phytoestrogen levels and their effect on lipoproteins, including total, LDL- and HDL-cholesterol and triglycerides, in women undergoing coronary angiography for suspected ischemia. Baseline evaluation of participants included physical exams along with blood lipoprotein, phytoestrogen and reproductive hormone measurements.
Findings indicate a "very significant relationship," says Dr. Bairey Merz, between increased phytoestrogen levels and lower total cholesterol, LDL-cholesterol and triglycerides and higher HDL-cholesterol -- all established factors in decreased heart disease risk.
Another arm of the study examined phytoestrogen levels and their relationship to brachial artery reactivity -- the ability of arteries to dilate in response to stress brought on by inflating and deflating a blood pressure cuff.
"This is very important, because arteries that lose their ability to dilate typically are or will become diseased," says Dr. Bairey Merz. For this phase of study, women undergoing coronary angiography for suspected ischemia were evaluated through physical exams as well as determinations of blood lipoproteins, phytoestrogen and reproductive hormones. Flow-mediated dilation of the brachial artery was conducted to gauge arterial function. Among the six phytoestrogens measured, only genstein demonstrated a significant association to increased arterial dilation.
"In these studies, results showed positive associations with phytoestrogens that were independent of blood estrogen levels and hormone replacement therapy," Dr. Bairey Merz states. "Additional research will be required to determine the relationship between phytoestrogens and blood estrogen levels in women, though animal studies have indicated a synergy between the two that produces beneficial results."
In January, Dr. Bairey Merz and her colleagues will launch an ancillary study, funded through a $150,000 annual grant from the Cedars-Sinai Women's Guild, to further analyze stored blood samples. "While NHLBI paid for the basic tests for this study, costs associated with expanded analysis of 1,000 samples are naturally very high, though the wealth of information to be gleaned will prove invaluable."
In future research, investigators will need to look at the merits of consuming phytoestrogens in plant form versus capsules, says Dr. Bairey Merz, explaining that previous studies have found artificial forms produce less positive results. "This probably means we should be eating beans as opposed to taking supplements in capsule form," she adds.
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