I have just reached 1 Tbs a couple of days ago and it seems to be really helping BMs.
This sounds good.
RS2 is what is in a raw potato, green banana, and raw starches. It is resistant to digestion because of it's shape, size, and physical characteristics.
RS3 is formed when amylose starch (but not amylopectin) cools. It gels together under heat, and when it cools, it forms a crystalline structure known as retrograded starch. This retrograded starch is again in a form that stomach acid and normal digestive processes can't break down.
Both types of RS are fermented primarily by beneficial bacteria and produce SCFA, but each type of RS is fermented by different microbes which is why I think it's important to eat a variety of RS sources--raw starch AND RS-rich foods AND cooked and cooled starches.
So it makes sense to take RS2 from raw PS, and additionally eat cooked and cooled rice (or potatoes) to obtain RS3, and therefore we create more different microbes.
Best regards, jepps