If you *blend* it, not much disappears. However, there are enzymes in your saliva that help break down food as you chew, so drinking a smoothie doesn’t always give you the exact same nutrients as eating whole fruit. You can “chew” your smoothie to mitigate this.
The place you lose the fiber is when you only drink the juice of a fruit, because the “pulp” is where the fiber is. Pure fruit juice is “natural”, but it’s hardly better than soda in many regards.
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