Worcestershire sauce typically contains anchovies, which can pose a kosher issue. In Jewish dietary law, certain fish, including shellfish and some types of fish that are not considered kosher, are prohibited. Anchovies, being a type of fish, must come from a kosher source and be prepared according to kosher regulations to be considered acceptable.
In the production of Worcestershire sauce, if the anchovies are not sourced from a kosher supplier or if they are not processed in accordance with kosher guidelines, then the entire sauce may not be deemed kosher. This makes anchovies a significant concern for those adhering to kosher practices. Other ingredients like salt, vinegar, and garlic do not typically present the same level of concern regarding kosher status as they can usually be found in kosher formulations.