Much of the research on health-promoting activities of soy products has been conducted focusing on the role of isoflavones. However, other soy constituents including dietary fiber, oligosaccharides, proteins, trace minerals and vitamins can also influence well-being and influence the efficacy of isoflavones. As a culture system for gut microflora, a Simulator of the Human Intestinal Microbial Ecosystem (SHIME) was used to evaluate the capacity of SoyLife COMPLEX (standardized on 2% isoflavones) to modulate colonic fermentation. In addition, it was studied to what extent the microbiota metabolized the conjugated isoflavones present in the soy germ powder into aglycone isoflavones. The microbiota was subjected to a 2-week treatment by adding 2.5 gram per day of SoyLife COMPLEX to the culture medium
Other soy constituents including dietary fiber, oligosaccharides, proteins, trace minerals and vitamins can influence wellbeing and impact the efficacy of isoflavones. Studies indicate the ability of soy germ powder to positively influence the composition of the gut microflora. This suggests that SoyLife has a prebiotic activity.
Addition of SoyLife isoflavone-rich soy germ concentrate resulted in an overall increase of bacterial marker populations,with a significant increase of the Lactobacillus sp. population.
Gas analysis revealed a significant increase of methane concentration. The use of an electronic nose apparatus indicated that odor concentrations after passage through the intestinal tract decreased significantly during the treatment period. A third observation from this study concerns the estrogenic activity of isoflavones. To enable this activity, glucosides are hydrolysed into aglycones by cleaving the β-glycosidic bonds. This study showed that a change in microflora increased the hydrolysis rate of the isoflavone glucoside, thus resulting in more aglycones. Using a yeast estrogen screen, the estrogenic activity was demonstrated in the crude SHIME-fermented extracts.
This was the first study showing the ability of soy germ powder to positively influence the composition of the gut microflora, suggesting a prebiotic activity. The estrogenic activity of SoyLife was also confirmed.
- De Boever et al 2000 Fermentation by gut microbiota cultured in a simulator of the human intestinal microbial ecosystem is improved by supplementing a soy germ powder, J. Nutr. 130 (2000), 2599-2606.
- De Boever et al 2001 Combined use of Lactobacillus reuteri and soy germ powder as food supplement, Letters in Applied Microbiology 33 (2001), 420-424.