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Resistant starch RS2

Resistant starches

A raw starch granule, so dense that enzymes cannot get in. It disappears with cooking.

So it is eaten raw or as an unheated powder: green banana, raw starch, green banana flour.

Effects and benefits

A raw starch granule is so compact that our enzymes slide right off it. Green banana and raw potato starch deliver an untouched feast to the colon. In trials, a few weeks were enough to raise butyrate and make the body more sensitive to insulin.

Under the microscope, raw potato or green banana starch forms tight granules, organized like a crystal. During cooking, water rushes in, they swell and burst: the starch becomes digestible. A banana loses its starch as it ripens, turning it into sugars — which is why a ripe banana is sweet.

Its effects have been measured. In a four-week controlled trial, 30 g a day of high-amylose corn starch improved insulin sensitivity in healthy volunteers (Robertson et al., 2005). In another, raw potato starch raised stool butyrate within two weeks, with big differences from one person to the next depending on the bacteria present (Venkataraman et al., 2016).

The effect on blood sugar applies to all resistant starches: replacing some of the digestible starch in a meal contributes to a reduction in the blood glucose rise that follows (Regulation 432/2012).

A big dose all at once causes gas while the bacteria able to break it down multiply: better to increase gradually over two or three weeks.

Sources: Robertson et al., AJCN, 2005 · Venkataraman et al., Microbiome, 2016 · EU Regulation 432/2012

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Its category
Resistant starch