The goal of this study was to see if adding rice bran fermented with the mushroom Lentinus edodes (known as rice bran exo-biopolymer, or RBEP), which contains a substance called arabinoxylan, could boost the activity of natural killer (NK) cells and affect the production of certain immune-related proteins called cytokines in healthy adults. To test this, researchers conducted a randomized, double-blind study, meaning neither the participants nor the researchers knew who was receiving the supplement or the placebo. Eighty healthy people with normal white blood cell counts were chosen to participate. They were randomly divided into two groups: one group took six capsules of RBEP (3 grams) each day, while the other group took six placebo capsules (3 grams) daily, for a period of eight weeks. Three participants in the placebo group dropped out after the study began, but importantly, no severe side effects were reported from taking RBEP.
To measure the effects of RBEP, the researchers looked at how active the NK cells were in the participants’ blood using special testing kits that didn’t involve radiation. They also measured levels of various cytokines in the blood, including interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and interleukins like IL-2, IL-4, IL-10, and IL-12, using a cytokine testing kit.
The results showed that taking RBEP significantly increased the production of IFN-γ compared to the placebo group, with a statistical significance of P = 0.012. However, RBEP did not have any noticeable effect on the overall activity of NK cells or on the levels of other cytokines measured in the study.
These findings suggest that supplementing with RBEP can increase IFN-γ levels without causing significant side effects, making it potentially beneficial for healthy individuals. Because of this, RBEP might be a useful ingredient in the development of foods or supplements aimed at improving immune responses and helping prevent or manage conditions related to poor immune function.
Choi JY, Paik DJ, Kwon DY, and Park Y. Dietary supplementation with rice bran fermented with Lentinus edodes increases interferon-γ activity without causing adverse effects: a randomized, double-blind, placebo-controlled, parallel-group study. Nutr J. England; 2014;13:35
