VIP and constipation disorder: The correlation between the apparent indicators of constipation in the gastrointestinal tract and each related test index was established based on the results above, as shown in Figure 9A. The indicators that were positively correlated with stool water content were AA, PA, and SP, while the indicators that were negatively correlated were VIP, IL-1, IL-6, and IL-8, among which PA showed a significant correlation (p < 0.05).