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.
Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München
Second research flight into zero gravity
21.10.2016 | Universität Zürich
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences