The present invention relates to the manufacture of modified Metroxylon sagu (sago) starch through double modification processes of acetylation and crosslinking. Our invention showed that the resistant starch produced through chemical modification processes, once supplemented and fed into BALB/c mice, caused a shift of gut microbiome composition towards one that would be beneficial to human. Analysis of short chain fatty acid profile in fecal sample also showed an increase of preferred SCFA that could positively contribute to good health.