Left panel: helium abundance plot for three models with different implementations of turbulent diffusion. For the red curve, a constant mixing coefficient was applied throughout the structure and the evolution of the model. For the blue curve, we used an exponential decay starting from the base of the convective envelope of the model. For the green curve, we used an exponential decay starting from the surface of the model. For the magenta curve, we used a model including only microscopic diffusion. Right panel: the metallicity profiles of the three models described above.