Food–gut continuum of biofortified micronutrients: Influence of breadmaking processes on iodine, selenium, and zinc bioaccessibility and epithelial responses in an in vitro intestinal model

Abstract

Micronutrient malnutrition affects over 3 billion people worldwide. This study evaluated biofortified wheat breads with iodine, selenium, and zinc, applied individually or in combination, and examined mineral retention, bioaccessibility, and intestinal epithelial responses. Mineral concentrations in wheat and their changes after baking unfermented flatbread and fermented sourdough were quantified, while intestinal bioaccessibility and epithelial effects were assessed using in-vitro digestion and cell culture models. Biofortification significantly increased mineral concentrations in wheat; however, retention during baking varied by mineral and product. Flour composition and baking method influenced iodine and zinc levels, whereas selenium retention was primarily affected by wheat cultivar and fermentation. In biofortified Bezostaja-1, Se bioaccessibility reached 68% in flatbread, while iodine and zinc reached 49% and 12% in sourdough. Selenium enhanced mitochondrial activity in intestinal cells in both bread types, and zinc-enriched sourdough increased epithelial integrity by 15% and reduced cellular permeability by 30%. • Bread Se concentration was primarily affected by wheat cultivar and fermentation. • Flour composition and baking method influenced I and Zn levels in bread. • I and Zn were more bioaccessible in white sourdough breads than in whole wheat flatbreads. • Zn-enriched sourdough improved epithelial barrier resistance. • Se-biofortified breads enhanced mitochondrial activity in gastrointestinal cells.