Lactoferrin (LF) is a natural iron-binding protein found in milk. It exists either in an iron-free state (apo-LF) or bound to iron (holo-LF). Whether LF binds iron to facilitate its absorption and/or to sequester iron from potential enteropathogens remains uncertain. However, while LF is a promising tool for treating iron deficiency, it is sensitive to heat during food processing and to the acidic environment of the human stomach. This degradation often causes LF to lose its functional properties before it can promote iron absorption effectively. This study aims to evaluate whether encapsulating apo-LF (either alone or in combination with iron) can protect LF from digestion and enhance iron absorption. Using a randomized, crossover design, different encapsulation methods will be compared to determine which results in the highest iron absorption in women with iron deficiency. All test compounds will be labeled with stable iron isotopes. Participants will consume the labeled compounds with a test meal or water in a randomized order, allowing for within subject comparisons. Fractional iron absorption will be measured 17 days after administration via the incorporation of labeled iron into red blood cells.