Matrix effects of lupine (Lupinus luteus L.) and rapeseed (Brassica napus L.) products on in vitro non-haem iron availability from pork meat

Limited iron bioavailability is regarded as one of the most confounding factors responsible for low iron absorption and utilisation. In the gastrointestinal lumen of humans and monogastric animals, iron absorption is highly affected by dietary components that decrease or enhance iron availability. This study aims at investigating the matrix effects of lupine and rapeseed products on in vitro non-haem iron availability when included in meat-based diets. In vitro iron availability is measured as Fe(II) dialysability obtained by a method combining in vitro protein digestion and dialysis (IVPD dialysis). Aliquots were collected following digestion with pepsin or pepsin/pancreatin and investigated for their effects on Fe(II) dialysability. Thus, the IVPD imitates the conditions in the duodenum and the proximal jejunum. The method confirms that the major effects on in vitro non-haem iron availability are achieved during duodenal conditions. The results showed a significant enhancing effect of pepsin-digested pork meat on Fe(II) dialysability and a pronounced effect of the plant components on Fe(II) dialysability from meat proteins. Lupine enhances Fe(II) dialysability after pepsin/pancreatin digestion in contrast to rapeseed. Moreover, lupine may constitute a valuable vegetable food component in enhancing iron availability and solubility more distally in the intestine than observed for other enhancers of iron absorption.