Researchers led by academics from Tohoku University in Japan used a unique form of modified rice bran, which was fermented by both Aspergillus kawachii and Lactobacillus sp, enriched with free tryptophan and tryptamine.
To evaluate its potential protective effect, they determined the serum pro-inflammatory cytokines and colonocyte pro-inflammatory gene expression.
“Our results indicate a protective effect of dietary fermented rice bran on ulcerative colitis in the mouse model, linked to modulation of colonic short chain fatty acids and pro-inflammatory gene expression,” they wrote in the journal Nutrients.
The study divided mice into a control group, a group supplemented with rice bran, and a group supplemented with fermented rice bran.
After being subjected to induced ulcerative colitis, the results showed higher acute inflammation in the colonic tissues of the control and rice bran groups.
Serum levels of the pro-inflammatory cytokines TNF-α and IL-6 were also higher in the control and rice bran groups.
Furthermore, the high tryptophan and tryptamine content in the fermented rice bran increased the production of colonic SCFAs after the illness was induced.
The researchers hypothesised that the anti-inflammatory benefits of fermented rice bran may be caused by its high level of tryptamine.
“Although the fermentation process may enrich the protein and dietary fibre content in fermented rice bran, it is not known which specific component contributes to the reduction of colitis. Here, during fermentation, it became enriched by almost 10 times in tryptamine, which may act as an Ahr ligan. Ahr has been highlighted as an immunological regulator in inflammation.”
They added that although high levels of dietary fibre and prebiotics increase intestinal SCFA concentration, few studies had investigated their production during ulcerative colitis by fermented rice bran. In the current study, faecal and colonic SCFA levels were significantly higher in the fermented group than in control and rice bran groups.
“Prebiotic substrates that selectively promote the growth of beneficial microbiota also induce changes in SCFA production in patients with irritable bowel syndrome. Thus, fermented rice bran supplementation may alter the gut microbiota,” they wrote.
They concluded that dual fermentation of rice bran enriches its functional value.
“The current study demonstrates the potential of fermented rice bran consumption as a dietary supplement for preventing intestinal inflammatory disorders,” they added.
“Dietary Supplementation of Fermented Rice Bran Effectively Alleviates Dextran Sodium Sulfate-Induced Colitis in Mice”
Authors: Hitoshi Shirakawa, et al.