Soy waste compound may protect against inflammation

08-Dec-2009 - Last updated on 08-Dec-2009 at 09:25 GMT

A compound often discarded as waste in soy-processing plants may stop inflammation, and protect against chronic diseases like diabetes and heart disease, says new research.

A soy protein called lunasin was found to significantly reduce levels of the pro-inflammatory compound interleukin-6, according to results from the University of Illinois.

If the study can be repeated in humans it offers promise for preventing chronic inflammation, brought about by an over-expression or lack of control of the normal protective mechanism. Chronic inflammation has been linked to range of conditions linked to heart disease, osteoporosis, cognitive decline and Alzheimer's, type-2 diabetes, and arthritis.

The researchers, led by Professor Elvira de Mejia, have published a raft of papers supporting the benefits of the compound. A study published this year in the Journal of Agricultural and Food Chemistry supported the bioavailability of lunasin.

The bioavailability looked at the effect of consuming 50 grams of soy protein as part of a soy milk shake and a serving of soy chili for five days. “Significant levels of the peptide in the participants' blood give us confidence that lunasin-rich soy foods can be important in providing these health benefits,” said Elvira de Mejia.

The researchers followed this up with a study in Food Chemistry that reported the anti-inflammatory effects of lunasin for the first time. “We can see that daily consumption of lunasin-rich soy protein may help to reduce chronic inflammation. Future studies should help us to make dietary recommendations,” added de Mejia.

“We know that chronic inflammation is associated with an increased risk of malignancies, that it's a critical factor in tumor progression,” she added.

A third paper has just been published in Molecular Nutrition & Food Research, which reports that lunasin contains a specific sequence of amino acids - arginine, glycine, and aspartic acid – known as the RGD motif, which is known to offer cancer protective effects.

“Other scientists have noted the cancer-preventive effects of the RGD sequence of amino acids so it's important to find proteins that have this sequence,” said de Mejia.

Obtaining lunasin

While the results appear very promising for the development of a nutraceutical or lunasin-rich dietary supplement, the researchers note that it is relatively expensive to obtain lunasin from soy waste. On the flip side, soy flour does contain high concentrations of the peptide, said de Mejia.

According to the soybean germplasm collection maintained by the US Department of Agriculture (USDA) and housed at the University of Illinoi, some genotypes contain very high concentrations of lunasin, obviously making these of more interest for the development of lunasin-rich soy foods.

Sources:
1. Journal of Agricultural and Food Chemistry
Volume 57, Issue 4, Pages 1260-1266
“Presence of Lunasin in Plasma of Men after Soy Protein Consumption”
Authors: V.P. Dia, S. Torres, B.O. De Lumen, J.W. Erdman, Jr., E.G. De Mejia

2. Food Chemistry
Volume 114, Issue 1, Pages 108-115
“Isolation, purification and characterisation of lunasin from defatted soybean flour and in vitro evaluation of its anti-inflammatory activity”
Authors: V.P. Dia, W. Wang, V.L. Oh, B.O.de Lumen, E. Gonzalez de Mejia

3. Molecular Nutrition & Food Research
Published online ahead of print, doi: 10.1002/mnfr.200900073
“Lunasin, with an arginine-glycine-aspartic acid motif, causes apoptosis to L1210 leukemia cells by activation of caspase-3”
Authors: E.G. de Mejia, W. Wang, V.P. Dia