Effect of exogenous phytase added to small-quantity lipid-based nutrient supplements (SQ-LNS) on the fractional and total absorption of zinc from a millet-based porridge consumed with SQ-LNS in young Gambian children: a randomized controlled trial

Background: Dietary phytate inhibits zinc absorption from composite meals in adults. Objective: The objective of this study was to investigate the effect of adding exogenous phytase to a small-quantity lipid-based nutrient supplement (SQ-LNS) on zinc absorption among young children. Methods: In a double-blind randomized controlled trial, intraindividual differences in fractional and total absorption of zinc (FAZ and TAZ, respectively) from a millet-based porridge containing SQ-LNS with and without phytase were measured in 30 asymptomatic children 18-23 mo of age in the Kiang West district of The Gambia. Using a crossover design, children received for 1 d each porridge test meals with 20 g SQ-LNS containing 8 mg zinc and either 1) exogenous phytase or 2) no exogenous phytase. The test meals were provided on consecutive days in randomized order. FAZ was measured using a triple stable isotope tracer ratio technique with Zn-67 and Zn-70 as oral tracers and Zn-68 as the intravenous tracer. Results: Twenty-six participants completed the study. The prevalence of stunting and wasting were 20% and 13%, respectively; no children had low plasma zinc concentrations (<65 mu g/dL). Total mean +/- SD dietary zinc intake from the test meals was 7.3 +/- 2.2 mg (phytate:zinc molar ratio = 3.1 +/- 0.3, not accounting for phytase activity). Mean FAZ increased from 8.6% +/- 1.3% to 16.0% +/- 1.3% when exogenous phytase was added to the SQ-LNS product (P < 0.001). Mean TAZ from test meals containing SQ-LNS with phytase was more than double that from test meals containing SQ-LNS without phytase (1.1 +/- 0.1 mg and 0.5 +/- 0.1 mg, respectively; P < 0.001). Conclusions: The addition of exogenous phytase to SQ-LNS increased both FAZ and TAZ. These results suggest that phytate reduction may be an important strategy to increase zinc absorption among young children.