PSVIII-12 Phytate and mineral accessibility in commercial vegetarian and vegan extruded dog foods.

Abstract The vegetarian and vegan pet foods are on the rise due to societal concerns towards environmental sustainability and livestock welfare. The nutritional properties of these pet foods with plant-based (PB) protein sources may be different from conventional foods with animal-based (AB) protein sources. For example, plant protein sources can contain fibers and anti-nutrients like phytate and polyphenols that can bind with mineral ions and form insoluble complexes, which reduces the availability of minerals for intestinal absorption. and prevent their availability. Our objective was therefore to advance our understanding of mineral bioavailability in vegetarian and vegan pet foods. An inventory was made of commercial vegetarian and vegan dry extruded dog foods using Google as search engine. The form (entire or processed into concentrate or isolate) of the first protein source(s) to be listed were noted. Based on product availability in the web shops, fifteen vegetarian and vegan dry extruded foods were purchased. Seven popular conventional dog foods were selected as reference products. Foods were analyzed for phytate (myo-inositol hexaphosphate) contents. Foods were subjected to in vitro simulation of gastric and small intestinal digestion. Foods and their insoluble residues collected after digestion were analyzed for dry matter and mineral contents (Ca, K, Mg, Zn, Mn, Fe, Cu, S, Se) to allow calculation of mineral (in)accessibility. Differences in mineral accessibility (%) between AB and PB foods were evaluated by one-way ANOVA and, for Ca and Mg, with a Mann-Whitney U test. Correlations between phytate content (g/g) and mineral accessibility (%) and phytate content and inaccessible minerals (g/g) were evaluated. PB dog foods contained more phytate (average 0.61, range 0.21-1.31 g/100 g) than in AB foods (0.28, 0.11-0.50 g/100 g) (P=0.014). Foods differed in in vitro mineral accessibility with PB foods having lower Mn, Fe, Ca, K, Mg accessibility (P< 0.05) but higher Cu accessibility (P< 0.05) and similar accessibility values for Zn, S and Se (P >0.10) compared to AB foods. No significant correlations were observed between phytate content and mineral accessibility (P >0.05). Phytate content correlated only with inaccessible Mg content. The total Mg content in the food was, however, also significantly correlated with phytate content. In conclusion, mineral accessibility of commercial PB extruded dog foods is generally lower than those in conventional AB foods. Mineral contents in these foods require more attention when industry guidelines are to be followed. Phytate contents did not explain variation in mineral accessibility of foods, which suggests that other factors like mineral source, fibers and polyphenols may play a role.