Supplementation with high fiber bars developed to contain 30 grams of a combination of non-digestible soluble and insoluble carbohydrates of three or more monomeric units given daily over a 30-day period showed increased systemic short-chain fatty acid (SCFA) levels in RA patients, which are known to decrease inflammation by upregulating Treg cells, decreasing T cell proliferation, and decreasing IL-18 concentrations [32]. The gene discussed is IL18; the disease is rheumatoid arthritis.