Centrifugal juicers destroy the enzymes in the foods.
There is no scientific evidence available that is able to back this claim up. In fact scientific research shows that the centrifugal juicer has a lot of enzyme activity in it. The claim that centrifugal juicers destroy the enzymes because the heat caused by the friction due to the high speeds at which it runs simply aren't true. Heat caused through friction requires more than just fast speeds in order for the enzymes to be destroyed the juice itself would need to be heated well above blood temperature. Currently there are no juicers available which heat juice to this level.