Table 2.

Summary of nutrients discussed and their potential effects on Agvhd.

Nutrient	Effect on GVHD Outcomes	Study Type	Details	References
Tryptophan	Positive	Pre-clinical	IDO deficiency accelerated GVHD lethality. Exogenous metabolites reduced GVHD. Indoles protect against GVHD.	(30, 31, 35)
Tyrosine	Positive	Pre-clinical	Mice fed a tyrosine-supplemented diet showed prolonged survival and reduced tissue damage in one study. Tyrosine led to changes in gut microbiota composition.	(132)
Glutamine	Unclear	Pre-clinical and clinical	Glutamine improves intestinal barrier function but needs further study in the context of GVHD as current trials are small and limited.	(37–39)
Lipids	Negative/Unclear	Pre-clinical and clinical	Lipid-lowering drugs reduced GVHD. Fatty acid metabolism is implicated in clonal expansion and effector function of donor T cells. Increased risk of grade II-IV acute GVHD is associated with increased body mass index (BMI). Omega-3 fish oil worsened GVHD in one study.	(43, 49–54, 57)
Vitamin D	Unclear	Pre-clinical and clinical	Some studies associated vitamin D insuffiency/deficiency with decreased survival while others found no association. One study found higher incidence of acute GVHD in vitamin sufficient patients.	(61, 64, 65, 68–70, 72–74, 76)
Vitamin A	Unclear	Pre-clinical and clinical	Some clinical studies reported negative impacts of lower serum vitamin A levels on GVHD severity in pediatric patients, but it has also been reported that pre-transplant serum vitamin A levels do not appear to affect the development of aGVHD in adult patients. Preclinical studies regarding the effects of RA on GVHD also yielded mixed results.	(80–89)
Choline	Negative	Pre-clinical	A choline-rich diet accelerated GVHD-associated mortality and increased serum TMAO levels.	(90)
Lactose	Negative	Pre-clinical and clinical	A lactose-free diet reduced the abundance of Enterococcus and mitigated GVHD severity in mice. A lactose-free diet is commonly recommended for patients after HSCT.	(137, 138)
GOS	Positive	Pre-clinical	Mice supplemented with GOS had improved post-transplant survival when also treated with antibiotics.	(127)
FOS	Positive	Clinical	. Fructo-oligosaccharides are well-tolerated when given to HSCT patients and can modify gut microbiota composition and phenotypes of some immune cells.	(125)
Resistant Starch	Positive	Clinical	Resistant starch combined with other prebiotics reduced mucosal damage after transplantation, preserved microbiota diversity, and mitigated GVHD in one study.	(126)