Food Labeling Modernization Act of 2021 This bill imposes additional labeling requirements for food and addresses related issues. A food intended for human consumption must include on its principal display panel a summary of nutritional information using a system that (1) clearly distinguishes between products of greater or lesser nutritional value; and (2) uses standardized symbols to provide warning about products that are high in certain substances, such as trans fats. The Food and Drug Administration (FDA) must promulgate regulations establishing the requirements for such a system. Labels that use certain terms, such as whole wheat , fruit , or vegetable , must include additional information, such as the amount or quantity of that item in the food. The FDA must promulgate certain regulations relating to the use of the terms natural or healthy on food labels. The bill also imposes labeling requirements for certain foods that contain added coloring, added flavoring, phosphorus, caffeine, gluten, allulose, polydextrose, sugar alcohols, or isolated fibers. The FDA may, by regulation, deem a food ingredient to be a major food allergen. The FDA must also impose certain restrictions on the types of beverages that may be identified as infant formula or formula. The FDA must require food manufacturers to submit all information on the label of a food offered for sale in package form and update such submissions as necessary. The information must be made available in a public database on the FDA's website.