Mango and banana derived resistant starch: Narrative review of biochemical mechanisms, human clinical evidence, and metabolic health

The global rise of obesity, type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD) now more commonly termed “metabolic (dysfunction)-associated fatty liver disease” (MAFLD) underscores the need for dietary carbohydrates that mitigate postprandial hyperglycaemia and insulin resistance. Tropical fruits mango (Mangifera indica L.) and banana (Musa spp.) emerge as sustainable sources of resistant starch (RS) types RS2 and RS3 alongside bioactive polyphenols. This review synthesizes biochemical, preclinical and human evidence on mango/banana-derived RS mechanisms within the gut-pancreas-liver axis, highlighting fruit-specific pathways, food matrix interactions and South Asian translational potential. Narrative synthesis of studies on RS classification, structural characterization, phytochemical profiles, glycaemic mechanisms (SCFA production, incretin secretion, epigenetic modulation), gut microbiota remodelling and human intervention trials was conducted. Evidence from mango kernel RS3, green banana RS2 and general RS meta-analyses were integrated with emphasis on Sri Lankan public health relevance. Mango yields retrograded RS3 via processing while green bananas provide native RS2 with B-type crystallinity. Both resist small intestinal digestion, promoting colonic fermentation to short-chain fatty acids (SCFAs) that activate G protein-coupled receptor 41/43 (GPR41/43), stimulate glucagon-like peptide-1 (GLP-1) and enhance insulin sensitivity via AMP-activated protein kinase (AMPK). Human trials demonstrate 15-40 g/day RS reduces fasting glucose, HbA1c and HOMA-IR, particularly in prediabetes/T2DM. However, evidence for mango- and banana-derived RS is predominantly indirect, based on whole fruit consumption studies and general RS meta-analyses rather than trials using isolated mango or banana RS. Nonetheless, mango and banana-derived RS exemplify sustainable functional food ingredients for glycaemic control through complementary structural forms (RS2 and RS3) and phytochemical synergies. Well-powered randomized controlled trials using standardized fruit RS with continuous glucose monitoring endpoints are needed, alongside sustainable byproduct utilization strategies for South Asian metabolic disease prevention.