Abstract
[Purpose] High amylose wheat flour (HAW) contains various fermentable dietary fibers, including resistant starch (RS). Previous culture tests have confirmed that the occupancy of beneficial bacteria increased and the occupancy of harmful bacteria decreased when HAW was used as the substrates. This study aimed to elucidate the immunomodulatory effects of HAW through improvements in intestinal environment via a human pilot trial. [Methods] 36 healthy adults, who were aware of their susceptibility to colds, had a stool frequency of 5 times per week or less, and experienced fatigue, were randomly assigned to one of three groups (HAW high-mix bread (RS 5.9 g/d) intake group, HAW low-mix bread (RS 3.7 g/d) intake group, and placebo group), and they consumed the respective foods for 12 weeks. Immune indices (e.g., secretary immunoglobulin A (s-IgA), plasmacytoid dendritic cells (pDC) activity) and intestinal environmental indices (e.g., intestinal bacterial prevalence) were evaluated. [Results] The efficacy analysis subjects were 33 participants. No significant changes in fecal s-IgA were observed. The HAW high-mix bread intake group demonstrated significantly higher pDC activity (CD80) than the placebo group. The group also showed increased occupancy of Faecalibacterium genus (butyrate-producing bacteria), and a tendency toward decreased occupancy of Bilophila genus (harmful bacteria), compared with the placebo group. The HAW low-mix bread intake group had significantly lower scores related to body conditions (sneezing, sore throat, cough, arthralgia, sweating, chill), compared to the placebo group. This study suggests that HAW consumption may lead to immune modulation through enhancement of the intestinal environment.
