Objective: To measure the stability of pea ferritin iron under simulated gastric conditions and measure iron intake into intestinal cells.
Design: Intestinal caco-2 cells were introduced to two types of pea ferritin iron – one exposed to gastric acid and one not – and absorption was tested. This was in combination with dietary inhibitors of iron absorption. The production of free radicals was also compared between pea ferritin iron and ferrous sulphate.
Results: The pea ferritin exposed to an acidic pH of 2-4 (simulating stomach conditions) was degraded by 50-70% and its iron released for absorption by normal, nonheme iron pathways. The absorption was 26-40% worse than the native pea ferritin not exposed to an acidic pH, which was instead absorbed into intestinal cells with the protein cage intact. Compared to ferrous sulphate, the native, non-degraded pea ferritin iron resulted in 60% fewer free radicals produced than ferrous sulphate. The non-degraded pea ferritin iron absorption was also unaffected by dietary chelators of iron.
Conclusions: Some studies with soybean have shown that native legume ferritin is unaffected/undegraded by gastric acid conditions, but this study found that pea ferritin is. Enteric coating of pea ferritin iron could help ensure its optimal absorption. Intact pea ferritin iron is absorbed into intestinal cells by endocytosis, with its protein cage intact and is less irritating to intestinal cells.