Effect of Allium spices (garlic and onion) on the bioaccessibility of iron from Moringa oleifera leaves.

The aim of this study was to investigate the effect of garlic and onion, two Allium spices rich in sulfur compounds, on the bioaccessibility of iron from Moringa oleifera leaves. We first quantified anti-nutritional factors in various cooked mixtures of Moringa oleifera leaves and spices, with increasing level of incorporation of garlic or onion. We then assessed the iron bioaccessibility of the various mixtures using a simulated in vitro digestion method. Finally, we studied the speciation of bioaccessible iron. Total phenols contents ranging from 801.44 to 903.07 and from 869.78 to 990.72 mg/100 g of dry matter in garlic and onion mixtures, respectively, increased ( p  < .05) with the level of incorporation of spices. Phytates contents followed the same tendency with values ranging from 1.84 to 2.12 and from 1.75 to 2.02 mg/100 g of dry matter in garlic and onion mixtures, respectively. Although the presence of garlic and onion significantly reduced ( p  < .05) the total iron content of the mixtures (11.56-11.96 mg/100 g of dry matter), we noticed that bioaccessible iron was significantly higher ( p  < .05) in spiced mixtures (36.35%-48.40%) compared to the control (23.28%), with the greatest amount found in the mixture containing 10 g of onion. The predominant specie of bioaccessible iron was organic iron, whose amounts in the spiced mixtures (0.59-0.69 mg/L) were all significantly higher ( p  < .05) than in the control (0.32 mg/L). Globally, the presence of spices produced no significant variation ( p  > .05) in amounts of ferrous iron, the major inorganic specie of bioaccessible iron. The use of garlic and onion as ingredients could help improving the iron status of populations consuming iron-rich leafy vegetables.