Comprehensive modulatory effects of whole grain consumption on immune-mediated inflammation in middle-aged and elderly community residents: A real-world randomized controlled trial

Abstract

Whole grain consumption is widely recognized as a vital component of a balanced diet. Dietary fiber has been well-documented to play a crucial role in these health benefits attributed to whole grain intake. However, population-based evidence directly linking whole grain consumption to anti-inflammatory effects, especially in the context of immune-mediated inflammation, remains limited. We hypothesized that whole grain consumption promotes health by modulating immune-mediated inflammation. This study was designed as a real-world, population-based randomized controlled trial. We compared the effects of whole grain versus refined grain consumption on immune-mediated inflammation through staple food substitution, while participants maintained their usual dietary practices. The results demonstrated that whole grain consumption significantly reduced circulating levels of pro-inflammatory cytokines IL-22 and IL-23 compared to refined grain consumption. These reductions were associated with optimized short-chain fatty acid profiles and changes in CD4 + T cell subset distributions. The findings suggest that the anti-inflammatory effects of whole grain consumption in middle-aged and elderly populations are mediated by targeting specific CD4 + T cell subsets, in addition to modulating both upstream short-chain fatty acid composition and downstream expression of the pro-inflammatory cytokines IL-22 and IL-23. • In this investigation, we employed a method of substituting staple foods to examine the impact of varying grain consumption on immune-mediated inflammation and its associated metabolic endpoints. • Whole grains exhibit a comprehensive anti-inflammatory effect mediated by immune-induced inflammatory responses, involving T cell subsets, upstream short-chain fatty acids, and downstream inflammatory cytokines. • Whole grains may exert anti-inflammatory effects by reducing the circulating levels of IL-22 and IL-23. This effect may be linked to improvements in short-chain fatty acid composition and the distribution of CD4+T cells.