Shawn can correct me, but in my limited knowledge of this, my understanding is... Everything is energy - your body, your food, your home, etc - and it all has a vibration. When your energy is in harmony with your surroundings, food, etc it creates an optimal environment for peace, health, etc. to flourish. (I'm taking this class for my environment and Spring Forest QiGong for myself - love them both!)
Shawn mentioned "The Messages in Water" by Emoto... it's fascinating! And you can see where even something as good for you as water could potentially impact you negatively if the energy is "off". What I get from all this is that food/drink has an energy that is not necessarily connected to whether or not the food/drink is considered nutritionally good for you. If you bump up/bless it, it harmonizes the food/water so it doesn't negatively impact your energy... but it doesn't change how nutritional it is. I now bump/bless all my food/drink.
Hope this makes some sense! 🙂