Soy Peptide Reduces Cancerous Tumors

URBANA, Ill.University of Illinois researchers studying the effect of the soy protein peptide lunasin on colon cancer metastatis discovered when administered orally to mice at 20 mg/kg body weight, lunasin reduced the number of metastatic tumors by 94% (Journal of Cancer Therapy 2013; 4(6A2): 34-43).

While a previous study demonstrated soy peptide injections in combination with the chemotherapy drug oxaliptin produced a six-fold reduction in metastic tumors to the liver, this study highlighted the efficacy of lunasin acting on its own and used in oral form. Elvira de Mejia, professor of food chemistry and food toxicology at the University of Illinois, Urbana, IL, said, After all, soy is a food and we wanted the animals to consume it as a food. Because this lunasin would be digested, we needed to figure out how much should be fed to achieve the desired concentration in the bloodstream."

Using mice that had been injected with human colon cancer cells, the scientists began by feeding the animals 8 mg/kg of lunasin daily, which reduced the number of new tumors in the liver by 55%. They increased the dose five times, at last achieving a 94% reduction in tumors at 20 mg/kg of lunasin, reducing the number of tumors from 18 to one.  

Although results were short of statistical significance from the control group, said de Mejia, Its a small study but very promising."

The scientists plan to repeat the study again using 30 mg/kg of lunasin as soon as they can obtain funding. One tumor is still too many. Wed like to see no tumors," said de Mejia.

The scientists said that consuming the equivalent of 20 to 30 mg/kg of lunasin in soy foods would be daunting in terms of number of servings per day. But it would certainly be possible if food companies began to offer lunasin-enriched soy milk or yogurt," she said, noting that lunasin-enriched flour is already on the market.

De Mejia said that chronic daily exposure to lunasin could make an even bigger difference in terms of cancer development and metastasis. These animals were acutely exposed to the peptide for only 28 days, and we still achieved these results.

"There is evidence that lunasin accumulates in the body tissues, most notably the livers, of animals that have experienced chronic exposure to this bioactive component of soy. Consuming soy protein regularly in the diet could be important not only for nutrition but also for cancer prevention," she said. The researchers also plan to begin a year-long study that would model lifetime exposure to lunasin in transgenic mice programmed to develop colon cancer in contrast to a group that did not receive any lunasin.