Most starch is digested quickly in the small intestine. Resistant starch (RS) is the exception: it travels to the colon intact, where gut bacteria ferment it. That fermentation produces short-chain fatty acids — notably butyrate, the preferred fuel of the cells lining the colon.

Why green banana?

Unripe bananas are among the richest natural sources of type-2 resistant starch. As bananas ripen, that RS converts to sugar — which is why harvest timing and rapid, low-temperature processing decide the quality of a green banana powder. Powder dried too hot is just banana flour; powder dried correctly is a functional fibre ingredient.

What this means for your label

In most markets you can describe a finished product as a source of fibre or high in fibre once regulated thresholds are met, and describe resistant starch factually in the ingredient story. Disease-treatment claims are restricted for foods — keep them out of retail copy and let the science speak through your quality documentation.