Molecular Insight into the Binding of Heme to β-Lactoglobulin: Effect on the Intestinal Iron Absorption and Microbiota

Heme is widely recognized as an effective iron supplement. In vitro experiments suggested a relatively low bioaccessibility of free heme due to its strong hydrophobicity. The study prepared a β-lactoglobulin-heme nanocomplex (β-Lg-He) to improve the bioaccessibility of heme. The results indicated that heme could spontaneously bind to β-Lg mainly through hydrogen bonds and van der Waals forces to form water-soluble and uniform nanocomplexes. Simulated gastrointestinal digestion experiments showed that bioaccessibility of heme in β-Lg-He was more than 80%, while that of free heme was only about 8.0%, and the serum iron levels of mice in β-Lg-He groups were higher than those in heme groups and control groups. The results of in vivo experiments revealed that β-Lg-He could have a more beneficial effect on the intestinal microbiota of mice than free heme, which was an additional function for the high-efficiency iron supplement.