A functional food or designer food, also called fortified food,

The term applies to traits purposely bred into existing edible plants, such as purple or gold potatoes having increased anthocyanin or carotenoid contents, respectively. Functional food manufacturing has the intent "to have physiological benefits and/or reduce the risk of chronic disease beyond basic nutritional functions, and may be similar in appearance to conventional food and consumed as part of a regular diet".

The term also applies to food processing practices which include ingredients purposely added with the intent to improve the food health value and for marketing to specific consumer groups.

In the European Union, functional foods are conceptual rather than designated as a specific food category. The European Commission’s initiatives, such as the Concerted Action on Functional Food Science in Europe (FUFOSE) and the European Food Safety Authority (EFSA), define functional foods as those that beneficially impact body functions beyond nutrition, contributing to improved health or disease risk reduction

Definition

In 1998, the European Commission’s Concerted Action on Functional Food Science in Europe proposed in a European consensus document a working definition of functional food:

The concept includes the following unique features of a functional food:

  • being a conventional or everyday food,
  • being consumed as part of the normal/usual diet,
  • composed of naturally occurring (as opposed to synthetic) components, perhaps in unnatural concentration or present in foods that would not normally supply them,
  • having a positive effect on target function(s) beyond nutritive value/basic nutrition,
  • may enhance well-being and health and/or reduce the risk of disease or provide health benefit so as to improve the quality of life, including physical, psychologic, and behavioral performances,
  • having authorized and scientifically based claims.

A functional food can be:

Common ingredients intended to be functional when added to foods include polyunsaturated fatty acids, probiotics, prebiotics, vitamins with antioxidant properties, and protein.

As of 2025, leading product trends and motivations for choosing functional foods are for energy drinks, healthy aging, active living, and weight loss, among several others. Studies have shown that certain functional foods provide health benefits and prevent diseases. However, safety considerations should be paramount. Safety concerns have been raised on the addition of certain botanicals to food like beverages, cereals and soups some of which pose adverse health risks to consumers.

In 2001, the FDA issued letters warning the food industry concerning the use of certain "novel ingredients" in conventional foods.