CRP and irritable bowel syndrome: A meta-analysis of 12 randomized controlled trials (n = 611) and 4 observational studies (n = 359) noted that vitamin D supplementation in patients with IBD was effective in correcting their vitamin D levels, reducing C-reactive protein levels, and decreasing intestinal inflammatory activity, suggesting a role for vitamin D in the pathogenesis of IBD (Guzman-Prado et al., 2020).