Vitamin D

Meeker S, Seamons A, Maggio-Price L, Paik J.
Protective links between vitamin D, inflammatory bowel disease and colon cancer.
World J Gastroenterol. 2016 Jan 14;22(2):546-558.
doi:10.3748/wjg.v22.i2.546
PMID: 26811638
PMCID: PMC4716046.

Nerich, V., Jantchou, P., Boutron-Ruault, M.-C., Monnet, E., Weill, A., Vanbockstael, V., Auleley, G.-R., Balaire, C., Dubost, P., Rican, S., Allemand, H., & Carbonnel, F. (2011). Low exposure to sunlight is a risk factor for Crohn's disease. Alimentary Pharmacology & Therapeutics, 33(8), 940–945.

Vernia, P., Burrelli Scotti, G., Dei Giudici, A., Chiappini, A., Cannizzaro, S., Afferri, M. T., & de Carolis, A. (2017). Inadequate sunlight exposure in patients with inflammatory bowel disease. JGH Open: An Open Access Journal of Gastroenterology and Hepatology, 2(1), 33–38. https://doi.org/10.1111/1751-2980.12567