A Combination of Inulin and Long-Chain Fructooligosaccharides Enhances in Vitro Iron Bioavailability and Supports a Favorable Infant Gut Microbiome.

Iron deficiency is common during early life. Prebiotics may enhance iron bioavailability (IB) in the small intestine and in the colon. To study this, IMF was supplemented with inulin, lcFOS, their combinations (1:1 or 2:1), or scGOS:lcFOS (9:1). IMFs were digested in vitro, or fermented ex vivo yielding short-chain fatty acids (SCFA) and altering microbiota composition. Digested IMF containing either prebiotics or SCFA were incubated on Caco-2 cells to assess IB under simulated small-intestinal or colonic conditions respectively. Fermentation of inulin:lcFOS and scGOS:lcFOS increased Bifidobacteriaceae, reduced Enterobacteriaceae, and enhanced acetic acid (AA) production. Inulin:lcFOS increased small-intestinal IB (1.2-fold). SCFA from Inulin:lcFOS and scGOS:lcFOS increased colonic IB by 3.7- and 5.0-fold, respectively. When combining small-intestinal and colonic IB, overall IB increased ∼1.5-fold versus the control. Prebiotic-induced AA production played a key role in enhancing IB. Combining inulin or scGOS with lcFOS in IMF may improve iron absorption and support beneficial infant gut microbiota.