Yes—bananas can provide prebiotic-like substrates, but the amount and effect depend on ripeness. Less ripe (greener) bananas tend to contain more resistant starch, which escapes full digestion in the small intestine and can be fermented by microbes in the colon. As bananas ripen, sugars increase and resistant starch decreases, though fiber and certain oligosaccharides may still support a prebiotic effect. The goal of a prebiotic approach is consistent intake of substrates that beneficial microbes can use, in a dose that is well tolerated. Many people tolerate bananas well, but individual responses vary. Practically, pairing banana with fermented foods (yogurt/kefir) or other fiber sources (oats, nuts) can create a more balanced gut-supportive snack. For diabetes or insulin resistance, portion size and ripeness matter because very ripe bananas have a higher sugar load.