It is recently proposed by Wang et al. [Phys. Rev. B 61, R5090 (2000)] that dephasing of conduction electrons due to zero-point fluctuation of electromagnetic field in a vacuum can well account for the measured saturation of electron dephasing time at T→0 in various materials. We point out that this calculation is numerically incorrect, while we also provide arguments showing that zero-point fluctuation of electromagnetic field does not cause any dephasing within this theory of Wang et al.