Foraminiferal neodymium (Nd) isotopes are powerful proxies for reconstructing past deep-water currents. Nd isotopes were differentially enriched in foraminiferal calcite and associated authigenic phases (i.e., Fe-Mn oxides). The Nd concentration in the authigenic phases was higher than that in foraminiferal calcite, indicating that authigenic phases are the main carriers of foraminiferal Nd. Authigenic phases associated with foraminifera are generally formed at the seawater-sediment interface, from where they begin to adsorb Nd from the bottom water. During the diagenesis of sediments, the redox state of the sedimentary environment can be changed, resulting in the release and re-adsorption cycling of Nd isotopes in authigenic phases and the exchange with pore fluids, which further impacts the bottom water Nd isotope record in foraminiferal authigenic phases. Therefore, when using foraminiferal Nd isotopes to trace past bottom-water mixing, it is necessary to analyze the evolution of parallel rare earth elements and Nd isotopes extracted from foraminifera and detrital fractions to eliminate the influence of diagenesis on foraminiferal Nd isotopes.