The measurement of the plasma isotopic composition is necessary in future burning plasma devices such as ITER and DEMO as a tool for optimizing the DT fusion performance. This letter reports on the results of recent experiments performed on the JET tokamak where the radial profile of the plasma isotopic composition was measured using Toroidal Alfvén Eigenmodes (TAEs) with toroidal mode number (N) in the range up to |N| = 15. These results indicate that an active TAE diagnostic system with the capability of operating at multiple frequencies in ITER could provide measurements of the plasma isotopic composition not only supplemental to the standard neutral particle analyser and charge-exchange spectroscopy techniques, but also with the additional and much beneficial features of providing a radial profile of this quantity in real-time, i.e. on a sub-millisecond time base, with a much lower impact on the diagnostic volume occupied ex-vessel.