The writer of that phrase was not just referring to apple per se, but to all kinds of fruits because these are beneficial to the body, especially when eaten raw.
Fruits help our bodies flush out toxins. This is why vitamins have a fruit base.
Best Eaten Raw
Doctors specializing in end-stage cancer and other terminal diseases recommend eating raw food over cooked food, as the former will help the body resist cancer cells. In fact, they would classify food cooked at high temperature