Additional Analysis of Effects of Young Barley Leaf Powder on Immune Function —A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study

Abstract

Background: The health benefits of young barley leaves, known for their high dietary fiber content, have been explored over several decades. In a previous study on healthy adults, we found that intake of young barley leaf powder for 8 weeks notably reduced the number of cumulative days in which participants experienced cold-like symptoms compared to a placebo. This improvement was accompanied by increased expression of HLA-DR on a specific subset of conventional dendritic cells (cDCs), namely cDC1 cells characterized by CD11c, CD4, and CD141 expression. However, it remains unclear whether these findings extend to total cDCs and whether they are associated with T cell activation. Here, we conducted an additional analysis using samples from previous research to assess the impact of young barley leaf powder on the activation of total cDCs and T cells in healthy participants. Methods: We performed a randomized, double-blind, placebo-controlled, parallel-group study with healthy participants. Fifty-six individuals were enrolled and randomly assigned to groups receiving either young barley leaf powder or a placebo for 8 weeks. We assessed their immune functions by measuring the expression levels of HLA-DR, CD86, and CD40 on CD11c + cDCs, and CD69 on T cells at baseline and after 8 weeks of intake. Results: After 8 weeks, the expression levels of HLA-DR, CD86, and CD40 on CD11c + cDCs, as well as CD69 on T cells, were significantly higher in the group consuming young barley leaf powder compared to the placebo group ( P < 0.05). Conclusions: Intake of young barley leaf powder enhanced the activity of cDCs and T cells, and improved the physical condition of healthy adults.