Bioavailability of Zinc and Iron From a Whey-based Protein Supplement Consumed With a Habitual Plant-based Diet

Overview

Bioavailability of iron and zinc from habitual plant-based diets consumed by young children in Mexico is low due to the high phytate content. Whey protein has been found to increase zinc absorption, thus, providing a whey based supplement with micronutrients may be an effective strategy to increase iron and zinc bioavailability from plant-based foods and alleviate iron and zinc deficiencies. The investigators compared absorption of zinc and iron in children receiving diets with and without whey protein supplements (WPS).

Study 1: Zinc absorption studies The zinc study employed a 2-day cross-over design, labeling the WPS diet with a different zinc stable isotope (67Zn) than the control diet (70Zn). All meals during the 2-day period were labeled with tracer. The dual isotope ratio technique was used with a 3rd Zn stable isotope (68Zn) given intravenously and urine enrichment of all isotopes measured on Study Days 6-9 to measure fractional absorption of Zn (FAZ). The amount of Zn absorbed for the day was determined by multiplying the Zn intake for the day (determined from lab analyses of duplicate test meals) by the FAZ. Children (n=16) were randomized as to the order in which they consume the test and control meals on Study Day 1 and 2. Study 2: Iron absorption studies The iron study was a cross sectional study with one group receiving control meals and the second group receiving the same control meal plus WPS. Iron absorption was measured using the erythrocyte iron incorporation technique with labeling of all meals over 2 days (58Fe). This was preceded by a reference dose of Fe57 and ascorbate on the previous day. Children (n=32) were randomized to receive the control diet or intervention diet (control diet + WPS).

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