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With approximately 45 million Google results for “hyaluronic acid skin care,” even the most casual beauty enthusiasts consider themselves experts on the ingredient. They can pronounce it (“HY-uh-luh-RON-ic AS-id"). They can rattle off its basic benefits: It plumps! It fills fine lines! It’s bouncy! They’re aware that hyaluronic acid occurs naturally in the skin (it’s safe!) and attracts 1,000 times its weight in water (it’s hydrating!).