The science of resistant starch (RS2).
Green banana is naturally rich in type-2 resistant starch — native, granular starch that resists digestion in the small intestine and ferments in the colon as a prebiotic fiber. It is one of the most-researched functional fibers.
How RS2 behaves in the body
Native, granular RS2 resists digestion and travels through largely intact — not absorbed as sugar.
Gut bacteria ferment it as a prebiotic fiber — the basis for fiber and low-GI positioning.
Fermentation yields short-chain fatty acids such as butyrate, supporting a healthy gut microbiome.
The Hungry Microbiome
CSIRO — why resistant starch is good for you.
What makes it RS2
Resistant starch is grouped into four types. Green banana powder is RS2 — native and not chemically modified.
What the research looks at
Resistant starch is fermented in the large intestine, increasing short-chain fatty acids (especially butyrate) that feed colonocytes and beneficial bacteria.
Because it resists digestion, RS2 contributes fewer rapidly available carbohydrates than regular starch — relevant to low-GI formulation.
RS counts toward total dietary fiber and is studied for its effects on fullness and metabolic markers.
Resistant starch (RS) measured by AOAC Method 2002.02 (tested by SGS Vietnam). Information here describes resistant starch generally and is not a claim to diagnose, treat, cure or prevent any disease — formulators are responsible for finished-product claims. A reference list is available on request.
Resistant starch, answered
What is RS2 resistant starch?
RS2 is one of four types of resistant starch. It is native, granular, ungelatinized starch found naturally in raw potato and green (unripe) banana. Because its crystalline structure resists digestive enzymes, it passes through the small intestine largely intact and ferments in the colon as a prebiotic fiber.
How is RS2 different from RS1, RS3 and RS4?
RS1 is physically trapped in whole or partly milled grains and seeds; RS2 is native granular starch (green banana, raw potato); RS3 is retrograded starch formed when cooked starch is cooled; RS4 is chemically modified starch. Green banana powder is RS2 — native and not chemically modified.
Why is resistant starch good for the gut?
When resistant starch ferments in the large intestine it produces short-chain fatty acids, especially butyrate, which feed colonocytes and beneficial gut bacteria. This is the basis for its prebiotic and gut-health positioning.
Does RS2 raise blood sugar?
Because RS2 resists digestion, it contributes fewer rapidly available carbohydrates than regular starch, which is why it is studied in the context of low-glycemic (low-GI) formulation. It is not a medical claim — formulators are responsible for finished-product claims.
How much resistant starch is in green banana powder?
Prebyo's organic green banana powder provides more than 56 g of resistant starch (RS2) and more than 67 g of total dietary fiber per 100 g, tested by AOAC Method 2002.02.