Dampening gastrointestinal inflammation through nutrition

There are many ways to influence gut microbiota composition and modulate the immune response (prebiotics, probiotics…).³¹ One of the options is dietary interventions that have the potential to alter the activity of the local immune system, thereby dampening the increased inflammatory tone observed with these conditions - this is termed immunonutrition.³² The most widely studied immunonutrients include omega-3 polyunsaturated fatty acids (n-3 PUFA), vitamin D, arginine, nucleotides and glutamine.³²

Vitamin D and its effects on intestinal immune responses 

While the best characterized function of vitamin D is its role in controlling calcium levels and thereby maintain bone health, it is also known to have a significant effect on GI immune responses. Vitamin D regulates several genes that regulate gut barrier function as well as genes that encode antimicrobial peptides, thus helping to maintain intestinal balance (Fig 5).³³ It exerts an immunomodulatory effect, including immune cell differentiation, migration and anti-inflammatory functions,³⁴ and can act directly on Paneth cells to promote defensin-2 secretion.³⁵ Vitamin D also promotes the compositional diversity of the gut microbiota, leading to increased production of butyrate. Butyrate can exert anti-inflammatory effects, increase gut barrier function, and promote Paneth cells to secrete defensins (Fig 5). Interestingly, some probiotic bacteria (e.g. Lactobacillus strains) have been shown to increase vitamin D levels in the blood.³⁶

FIGURE 5: Effects of vitamin D on intestinal cells, gut microbiota and gut barrier.

Adapted from Chen J et al, 2021.³⁷