Writing in the journal Clinical Cancer Research lead author Virgilo Salvo from Tulane University in New Orleans reports that glyceollin compounds from the soybeans were successful in suppressing the growth of breast and ovarian cancer cell lines.
The study adds to an ever growing body of science linking soy consumption to a range of potential health benefits.
Indeed, 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 is said to be uncommon in today's clean, disease-free soy fields.
Co-author of the study, Stephen Boué from the US Agricultural Research Service, New Orleans spoke to NutraIngredients.com last year about his work on the production of new glyceollin-rich soybeans. Boué explained that the methodology used to produce the 'super' 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.
The new study looked at the effect of three glyceollins (I, II, III) extracted from A. sojae-challenged soybean seeds on the growth of human oestrogen-dependent breast cancer cells (MCF-7) and ovarian cancer cells (BG-1).
The cells were grafted onto female ovariectomised mice. Relatively high doses of the glyceollins were administered (20 mg per kg of mouse per day).
The researchers report that the glyceollins suppressed the tumour growth of MCF-7 cells by 53.4 per cent and the BG-1 cells by 73.1 per cent.
"This study is the first demonstration of ability of the glyceollin mix to significantly suppress oestrogen-stimulated tumour growth of MCF-7 and BG-1 cells in ovariectomised female nude mice," said the researchers.
"These findings identify glyceollins as antiestrogenic agents that may be useful in the prevention… of breast and ovarian carcinoma," they concluded.
Despite the relatively high glyceollin doses used in this study, corresponding author for the study, Dr. Matthew Burow told NutraIngredients.com: "As a dietary factor, the glyceollins would be predicted to reduce breast cancer incidence."
Dr. Burow based this on results of a collaboration with Wake Forest University that studied the short-term effects of the glyceollin-enriched soy protein in a postmenopausal primate model (Nutrition and Cancer, 2006, Volume 56, pp. 74-81).
"Although this study did not examine the effects of glyceollin on breast cancer directly, this study used a primate model to examine the effects of a glyceollin rich diet on measurable biomarkers of oestrogen action and breast cancer risk," he said.
Source: Clinical Cancer Research Volume 12, Pages 7159-7164 "Antiestrogenic Glyceollins Suppress Human Breast and Ovarian Carcinoma Tumorigenesis" Authors: V.A. Salvo, S.M. Boué, J.P. Fonseca, S. Elliott, C. Corbitt, B.M. Collins-Burow, T.J. Curiel, S.K. Srivastav, B.Y. Shih, C. Carter-Wientjes, C.E. Wood, P.W. Erhardt, B.S. Beckman, J.A. McLachlan, T.E. Cleveland and M.E. Burow