A north-south gradient, with an increasing trend reported in Northern countries, compared to Southern countries in Europe, could be a global phenomenon. 42 , 43 Environmental factors, such high temperature, latitude, and precipitation, could change microbial compositions and affect the development of IBD. 44 There is a hypothesis that summer temperature could be associated with a protective effect against IBD by affecting the richness of microbiome. 44 In addition to climate, various other factors, such as dietary habits and socioeconomic status, have also been shown to be associated with the incidence and prevalence of IBD.
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