There are several synonyms for the phrase "sustained by" that can be used depending on the context. Some possible substitutes include "supported by," "maintained by," "nurtured by," "upheld by," and "fostered by." All these phrases convey the idea that something or someone is being upheld or maintained by something or someone else. For instance, a business can be sustained by its loyal customers, a charity can be supported by its donors, and a person can be nurtured by their family. Choosing the right synonym for "sustained by" depends on the appropriate word choice for the surrounding context.