Plantains are related to bananas. They look similar, but plantains tend to have less sugar and more starch. This is good news because the kind of starch contained in plantains is resistant starch, a potent prebiotic.
What Are Prebiotics
Prebiotics feed the beneficial bacteria in our guts. Those little guys prevent the unwanted bacteria from taking over, which in turn keeps us healthier by boosting our immune system and our digestion, among other things.
Uses for Plantain Flour
Plantain flour can be used to make Paleo baked goods, but it has a pretty gritty texture. Most people use plantain flour as a supplemental form of resistant starch. You can mix it in some sparkling water or add a spoonful to your Paleo smoothie to make sure you get enough resistant starch in your diet.
Mark Sisson has more information on the benefits of resistant starch and how to include it in your diet.