Let's break down our two sources of fiber
Soluble fiber dissolves in water forming viscous gels. This precious fiber gel bypasses the digestion in the small intestine and is easily fermented by the microflora of the large intestine. The best sources are fruit, especially high pectin fruit such as apples, pears, plums, lentils, beans, and veggies such as carrots, onions, and artichokes.
Insoluble fibers are not water-soluble. They do not form gels due to their water insolubility but rather act more as a bulking agent in the gut assisting in elimination and the prevention of constipation. Gut conditions such as SIBO often arise from chronic constipation, or sluggish bowels. Insoluble fiber comes largely from whole grains, but also from a variety of fruits, vegetables, nuts, seeds and legumes.