Substituting other protein in the diet with soy protein may help to improve symptoms of inflammatory bowel disease, find researchers.
Researchers Zachary Bitzer and Amy Wopperer, former graduate students in the Department of Food Science at Pennsylvania State University (Penn State), conducted the research alongside Joshua Lambert, associate professor of food science in the College of Agricultural Sciences, and colleagues.
The team's findings were published in The Journal of Nutritional Biochemistry.
Finding ways to mitigate symptoms of IBD is of importance because the chronic inflammation that characterizes the disease is a major risk factor for colon cancer. Colonic inflammation is also responsible for the loss of gut barrier function and increased gut permeability.
Previous studies have explored the preventive effects that soybeans may have on cancer. While some studies have shown that consuming soy may reduce the risk of cancer, other studies have yielded mixed results.
Recent studies have uncovered that soy protein has promising outcomes in animal models of IBD. However, many questions about the underlying mechanisms behind the anti-inflammatory effect remain.
Soy protein concentrate triggered inflammation-moderating effects
The Penn State team examined the impact of soy protein concentrate on inflammation and gut barrier function in mice in the new study. They replaced 12 percent of other sources of proteins in the diets of the mice with soy protein concentrate. The doses of soy protein concentrate substituted were equivalent to the amount that could potentially be used in humans.
"We didn't want to get carried away with using doses that were really high and would crowd out all the other protein that was there," explains Bitzer. "Instead, we wanted to find a scenario that was going to fit into a more human-relevant situation."
The researchers found that soy protein concentrate has an antioxidant and cytoprotective effect in human bowel cells cultured in a laboratory. Furthermore, in the mice with induced IBD, substituting just 12 percent of other protein with soy protein concentrate was enough to stop body weight loss in its tracks and improve spleen swelling, reveals Lambert. This evidence indicates that soy protein concentrate might be able to moderate the severity of inflammation.
"Soy protein concentrate mitigates markers of colonic inflammation and loss of gut barrier function in the mice with induced IBD," says Wopperer.
Future studies by the investigators will try to determine whether their findings could be replicated in humans. Soy protein is a readily available food ingredient that is already used as a substitute for meat. Lambert believes that because of this, human studies could be just around the corner.
"Since it is already out there commercially, that makes it more straightforward. But practically speaking, the actual clinical studies are a little bit out of our area of expertise. I think the most likely thing to happen will be for us to try to identify a collaborator either through the Clinical Translational Science Institute on campus or with someone at the Penn State College of Medicine Inflammatory Bowel Disease Center."
Lambert and collaborators are currently evaluating whether the inflammatory-moderating effects they have observed in mouse colons are due to the soy protein or whether soy fiber may play a part. While soy protein concentrate contains around 70 percent protein by weight, it is also comprised of soybean fiber, Lambert concludes.