'Super soy' could help fight against breast cancer
The researchers, led by Prof Stephen Boue from the US Agricultural Research Service, New Orleans, have identified a group of compounds called glyceollins that have been shown to stop the growth of hormone-dependent breast cancer cells in the laboratory.
Population studies have shown that a diet rich in soy is associated with fewer cases of breast cancer, linked to the presence of soy isoflavones. China has the world's lowest incidence and mortality from breast cancer - a disease that has over one million new cases every year worldwide.
The concentration of glyceollins in commercial soybeans is very low since the compounds are only produced by soy as a defence mechanism from disease or infection, which Boue says is not common in today's clean, disease-free soy fields.
The research suggests possibilities for both the health food and pharmaceutical sectors, with talk of glyceollin-rich soy protein bars.
Talking to NutraIngredients.com, co-researcher Ed Cleveland said: "We are hoping to set up an industrial partnership, but because this research is very cutting edge there has been limited interest so far."
"We haven't reached the point where it's a manufacturing process yet. We are still talking lab-scale," added Stephen Boue. "It's very difficult to produce the glyceollins from seed."
Boue explained that the methodology used to produce the glyceollin-rich soybeans involves challenging just-germinated soybeans with the food-safe fungus Aspergillus sojae. The soybean believes it is under attack and starts producing the glyceollins as a defence mechanism.
There is a growing body of research that supports the cancer-protecting properties of soy.
A recent animal study published in the journal Cancer Research (Vol. 66, Issue 2) reported that high dietary intake of soy protected against breast cancer in postmenopausal monkeys.
This supports another study from the University of Ulster that focussed on the inverse link between soy and breast cancer. In this study, funded by the EU's "Quality of Life and Management of Living Resources" project, soy isoflavones were reported to inhibit breast cancer cell invasion in vitro.
The safety of the isoflavones was questioned however by a conflicting study that reported breast cancer cells in mice were stimulated by the compounds.
Toxicology studies involving primates for glyceollins are ongoing with no negative effects reported to date, but all aspects of the research have suffered setbacks due to Hurricane Katrina.
A US patent is pending, while several research articles have been submitted to peer-review journals concerning toxicology tests. NutraIngredients.com has not seen these results.
More support for soy's protection against prostate cancer
A diet rich in soy, sunflower seeds, berries and peanuts can reduce the risk of prostate cancer by 26 per cent, claims new research from Sweden.
Soy, beans and nuts contain phytoestrogens, oestrogen-like compounds found in plants. The phytoestrogens in soy are mostly isoflavones, while beans and berries contain lignans.
The new study, published in the journal Cancer Causes and Control (Vol. 17, pp.169-180), claims to be the largest such study in the western world. The diet of 1499 volunteers with recently diagnosed prostate cancer was compared with the diets of 1130 healthy control volunteers using dietary questionnaires.
A smaller group containing 209 cases and 214 controls underwent blood tests to measure the amount of the phytoestrogen enterolactone.
"High intake of food items rich in phytoestrogens was associated with a decreased risk of prostate cancer. The odds ratio (OR) [the risk compared to a standard of 1.00] comparing the highest to the lowest quartile of intake was 0.74," wrote lead author Maria Hedelin from Department of Medical Epidemiology and Biostatistics, Karolinska Institutet.
The case-control blood test group also showed that those with increased blood levels of enterolactone had a 70 per cent lower risk of prostate cancer.
"Our results support the hypothesis that certain foods high in phytoestrogens are associated with a lower risk of prostate cancer," said Hedelin.
The researchers could not conclude if the protection from prostate cancer was due to the phytoestrogens alone or a combination with other substances. They also recommended against taking supplements with high concentrations of artificial phytoestrogens, stressing that no clinical trials had been performed and such high doses could have side effects.
An animal study published in Biology of Reproduction (2004, Vol. 70, pp. 1188-1195) claimed that the metabolite of the soy isoflavone daidzein stopped the effect of the male hormone dihydrotestosterone (DHT), which has been linked to prostate growth and male baldness.
More study if required to identify which phytoestrogens are active, and further work is needed to identify the mechanism of protection.
Over half a million news cases of prostate cancer are diagnosed every year world wide, and the cancer is the direct cause of over 200,000 deaths. More worryingly, the incidence of the disease is increasing with a rise of 1.7 per cent over 15 years.
The lowest incidences of the cancer are found in China, Japan and India, with experts linking this to a high dietary intake of soy products. A recent meta-analysis from the International Journal of Cancer (2005, Vol. 117, pp. 667 - 669) reported that men who regularly consumed soy-containing products had a 30 per cent lower risk of the cancer.
By Stephen Daniells
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