Fiber from plant-based foods has been shown in scientific research to reduce the risk of post-traumatic stress disorder, also known as PTSD. There are two forms of fiber, soluble fiber and insoluble fiber. Research on more than 27,000 Canadians found that eating more fiber significantly reduces the risk of PTSD.
You can find references for this research at: https://plantmedicines.org/fiber-fruits-and-veggies-reduce-ptsd-anxiety-depression/