The effect of fortification on in vitro iron and zinc bioavailability in plant-based meat alternatives

Plant-based diets are increasingly popular due to their perceived health benefits and positive environmental impact. However, there are concerns that long-term adherence to plant-based diets could result in nutritional deficiencies, especially for minerals found in abundance in animal foods. Therefore, plant-based meat substitutes may be a vehicle for fortification to provide a source of bioavailable minerals. This study investigated the iron (Fe), zinc (Zn) and calcium (Ca) content and bioavailability from unfortified and Fe and/or Zn fortified plant-based mince (PBM) compared with animal mince. Total and bioaccessible mineral levels in animal mince, and PBM were determined using microwave digestion and in vitro simulated gastrointestinal digestion, respectively. Mineral bioavailability was assessed by exposure of Caco-2 cells to the digested food samples and measuring mineral uptake into the cells using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Total phytate levels were measured to calculate the phytic acid:mineral molar ratio (PA:Fe, PA:Zn, PA:Ca) as indication of the mineral bioavailability. Fe bioavailability from animal mince was significantly greater than from unfortified PBM. Fortification of PBM with Fe reduced the PA:Fe molar ratio to below 10, and increased Fe bioavailability compared with the unfortified PBM. Total Fe uptake from fortified PBM was equivalent to that from animal mince. Following fortification of PBM with Zn, the PA:Zn ratio remained high (>14), and bioavailability was not enhanced compared with the unfortified PBM (P > 0.1). This study highlights that Fe-fortified PBM can improve Fe bioavailability and provide similar amounts of Fe compared to beef mince, whereas more research is needed for Zn fortification of PBM. Fortification can be a promising approach to reduce the phytic acid:mineral molar ratio to mitigate the inhibitory effect of PA on mineral bioavailability.