E627 is a food additive meant to enhance flavor, and while it’s similar to sodium in use it’s sourcing is often not as innocent. While it’s not always the case E627 is often sourced from fish, making it non-vegan.
If you’re vegetarian or vegan I’d recommend avoiding products with it unless they market their self as vegetarian or vegan, as E627 is commonly sourced from fish. It can also be sourced from seaweed or yeast, so E627 isn’t always non-vegan, it’s just generally non-vegan as fish is a cheaper source.
What products contain E627?
Many packaged foods ranging from soups, canned “meats,” potato chips, rice snacks, and some canned vegetables (rare). Generally the foods that contain it are already non-vegan for other reasons, however sometimes it slips into an otherwise vegan food and spoils it.
I’d recommend searching for if the product you’re interested in that contains E627 is vegan, as odds are someone else has already asked the manufacturer if the E627 used in the product is vegan or not.