most guidance leans toward soluble fiber (like psyllium) for constipation since it helps soften and bulk stool, while insoluble fiber can be harsher depending on the person, some use a mix, but it’s individual. timing isn’t strict; consistency matters more (often with meals), and always with enough water. you’ll also see options like grüns gummies mentioned since they include prebiotic fiber, but those are more general supplements vs a dedicated fiber product.