Tunnelling allows a particle to cross an energy barrier in a way that is difficult to describe classically. Studies in biological systems normally combine temperature dependence, reaction rates, isotope substitution and structural changes rather than relying on a single measurement.
Work on photosynthetic electron transfer in 1966 and enzyme-catalysed hydrogen transfer in 1997 provides two representative lines of evidence, but each concerns a specific experimental system and does not show that every enzyme reaction is controlled by the same quantum mechanism.
The scientific value lies in mechanisms that can be challenged and replicated, not in using tunnelling as a promotional label for product effectiveness.
Studies of Photosynthesis Using a Pulsed Laser: Evidence for Tunneling ↗
A link between protein structure and enzyme catalyzed hydrogen tunneling ↗