Estimation of the iron bioavailability in green vegetables using an in vitro digestion/Caco-2 cell model

It is estimated that over 30% of the global population is anaemic, half of which is due to iron deficiency. The bioavailability of iron from vegetables is low and variable, and influenced by food composition and matrix. We have therefore determined the relative bioavailability of iron in five types of green vegetable, spinach, broccoli, savoy cabbage, curly kale and green pepper, by measuring the ferritin response in a simulated digestion/Caco-2 cell model. Savoy cabbage gave the highest ferritin response and analysis of the digest showed that the iron was present in low molecular weight fractions which contained glucose, fructose, organic acids and amino acids. The addition of fructose 1,6-biphosphate to the Caco-2 cells increased iron uptake 2-fold. These results demonstrate that cabbage was the best source of bioavailable iron out of the vegetables studied and suggest that the formation of complexes with fructose derivatives contribute to increase the iron bioavailability.