Assessing Iron Bioavailability in Biofortified Vegetables

Iron deficiency is a global problem for public health, even in countries with adequate food supply. According to the latest projections from the Global Burden of Disease Study in 2021, anemia affected more than 1.9 billion people worldwide (~ 24% global prevalence of anemia across all ages), with 1.3 billion cases attributed to dietary iron deficiency [1]. Boosting dietary iron supply through functional iron-biofortified vegetables like spinach and bell pepper could be a healthy and sustainable option to improve people's iron status.

Field trials in the BMBF-funded project EiBiG (“Enhancing the health value of vegetables by increasing the bioavailable iron content”) showed iron levels of non-biofortified spinach of around (0.7±0.1) mg Fe/100 g (wet weight), averaging across nine distinct varieties. A single foliar fertilization with Fe(ll) bisglycinate of these spinach varieties with

0.3 kg (Fe)/ha 7 days before harvest resulted in an average 2.2-fold increase in the iron content of the leaves. The bioavailability of iron in vegetables is investigated using combined systems of in vitro digestion and model intestinal cells Caco-2, with the iron storage protein ferritin as a biomarker [2]. In culture media-based model experiments undergoing a 24-hour incubation period, the bioavailability of Fe(ll) has been demonstrated to be approximately 2-fold greater than that of Fe(lll) sulfate at concentrations of 20 μM and 200 μM, respectively. Additionally, it has been demonstrated that oxalic acid reduces the bioavailability of Fe(ll) sulfate (20 μM) by (23±7)%.