Our knowledge of dietary factors affecting manganese absorption in man is very limited. In this study we used a recently developed radionuclide technique to measure manganese absorption in human adults. Using paired observations, we explored the effects of adding calcium and manganese to human milk on manganese absorption. Furthermore, the effects of adding phytate, phosphate, and ascorbic acid to infant formula as well as iron and magnesium to wheat bread were evaluated. Addition of calcium to human milk resulted in a significant decrease in manganese absorption whereas no significant differences in manganese absorption were observed as a result of the other test meals administered with and without the evaluated dietary component, respectively. Thus, manganese absorption was not significantly affected by most dietary factors evaluated in this study, except for the addition of calcium to human milk.