Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Soy intake associated with reduced risk of breast cancer

05.04.2006
But meta-analysis does not uncover enough benefits to recommend use of soy supplements

Because some studies have suggested that soy contains chemicals that may help ward off breast cancer, increasing numbers of women are using soy supplements as a potential tumor preventive. But although a new meta-analysis of all available published data finds that while soy intake may be associated with a small reduction in the risk of breast cancer, there is no evidence to recommend the use of supplements, say scientists at Georgetown University Medical Center and Johns Hopkins School of Medicine. The research team will publish its findings in the April 5 issue of the Journal of the National Cancer Institute.

This conclusion may come as a surprise to many women who have come to depend on soy supplements to limit their risk of either developing breast cancer, or reducing breast cancer recurrence, says Robert Clarke, Ph.D., D.Sc., a professor at Georgetown’s Lombardi Comprehensive Cancer Center.

"Soy supplements contain high levels of isoflavones, such as genistein, that have estrogenic properties, while in soy foods isoflavones are just a part of the package. "Estrogens make the breast tumor cells grow," says co-author Leena Hilakivi-Clarke, PhD, a professor of Oncology whose laboratory at Lombardi has long studied the role of food-based estrogens in cancer prevention. "We found that soy food intake was associated with a reduced breast cancer risk. However, we have no idea what soy supplements might do," she adds

After research more than a decade ago showed that soy could play a role in decreasing LDL (known as the "bad" cholesterol) levels in humans, U.S. sales of soy-based food, drinks and supplements increased. But although U.S. sales of soy-based food and drinks were $3.9 billion in 2003, sales have slowed in recent years, according to the Soyfoods Association of North America, an association funded by the soy industry.

"Because soy foods and soy supplements are widely used, we conducted this first true meta-analysis to understand what role soy foods might have on breast cancer risk," said Clarke. "This objective examination of all of the studies tells us that currently, the data are not adequate to provide a clear answer to recommend soy foods to prevent breast cancer."

Although the study did not address the link between soy use and breast cancer recurrence, Clarke and Hilakivi-Clarke again cautioned against overuse of soy supplements, particularly by women at high risk for breast cancer or breast cancer survivors.

In the same way that estrogen-based hormone replacement therapy may be contraindicated for some women at high risk to develop breast cancer, soy isoflavone supplementation may not be a good idea for these women either, the researchers said. Co-author Bruce Trock, PhD, of the Johns Hopkins School of Medicine added, "High-dose soy or isoflavone supplements have biological effects that are different from normal soy foods, and no one has studied the effect of long-term consumption of such supplements."

"Soy foods like tofu and soy milk are readily available now if women want to add them to their diet," Trock said.

Because soy has recently become a widely used food additive in the United States, many Americans get some soy that they are not aware of, said Hilakivi-Clarke. "Our data suggests that women do not need to consume very much soy to possibly benefit from it. Higher soy intake does not provide additional risk reduction," she said.

To conduct the meta-analysis, Clarke, Hilakivi-Clarke, and Trock looked at 18 epidemiologic studies published between 1978 and 2004 that examined the association between soy intake and breast cancer risk. Some of these studies were based on the hypothesis that Asian women have reduced incidence of breast cancer, compared to American women, because they have traditionally eaten a diet rich in soy foods, such as tofu. In some studies, soy foods were just one of the food items studied in connection to breast cancer risk.

The results of the meta-analysis indicated a small association between soy intake and a reduced risk of breast cancer. Risk appeared to be reduced to a somewhat greater extent in premenopausal than postmenopausal women, however only 10 of 18 studies evaluated the effect separately by menopausal status. Studies that did not address menopausal status provided less evidence for the risk reducing effect.

While the data were too inconsistent to recommend soy as a breast cancer preventive, the authors say there is no evidence to suggest that consumption of soy foods in amounts consistent with an Asian diet is detrimental to breast health. Any overall health benefits offered by traditional soy foods in the diet, modest though they may be, likely outweigh any risks for the population as a whole, the authors said.

Liz McDonald | EurekAlert!
Further information:
http://lombardi.georgetown.edu
http://www.georgetown.edu

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Targeting headaches and tumors with nano-submarines

20.07.2018 | Health and Medicine

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>