Invited commentary Functional foods or functionally marketed foods? A critique of, and alternatives to, the category of ‘functional foods’

The term ‘functional foods’ is a relatively new food category or concept, originating in the 1980s and becoming more widely used over the past decade. The ‘functional foods’ concept has been notoriously hard to define. Discussions of functional foods often begin by acknowledging that there are no generally accepted definitions of ‘functional foods’ and note the ‘ambiguity of definition and interpretation’. But the term continues to be used as if it does have a clear meaning. The term ‘functional foods’ is generally understood to refer to foods with especially healthful qualities, but there is little clarity as to what types of foods they are, what types of healthful qualities they possess and how they differ from other foods. While there is much debate over the nutritional or public health merits of ‘functional foods’, there has been little rigorous interrogation of the definitions of ‘functional foods’ nor of the usefulness and accuracy of the term itself, even from critics of ‘functional foods’. This commentary proposes that most definitions of ‘functional foods’ are inadequate – indeed that the term itself is inappropriate and misleading – and instead suggests alterative ways of categorising these foods. The examples of ‘functional foods’ commonly put forward include relatively novel food products (e.g. cholesterol-lowering margarines), whole foods that have been nutritionally modified (e.g. reduced-fat milk and genetically engineered ‘Golden Rice’), unmodified whole foods (e.g. nuts and fruit), and nutrient-fortified highly processed foods (e.g. sugar-laden breakfast cereals and ‘energy’ drinks). The diverse range of foods included in the ‘functional foods’ category is reflected in the diverse, confused and often self-contradictory definitions that are commonly espoused. Most definitions of ‘functional foods’ – and even the very term itself – suggest that these foods contain some intrinsic, health-giving, ‘functional’ components and qualities that distinguish them from other, ‘non-functional’ foods. However, I argue that there are no credible definitions of ‘functional foods’ that establish criteria for distinguishing between these and other foods (i.e. ‘non-functional foods’) in terms of any intrinsic, health-enhancing characteristics. Instead, the main distinguishing features of foods defined as ‘functional foods’ appear to be either that they have been ‘nutritionally engineered’ and/or that they are promoted with nutrient-content claims or health claims. The heavily loaded term ‘functional foods’ should therefore be rejected, in favour of other categories that more accurately describe the types of foods being referred to. The three more precise and appropriate terms I suggest are ‘functionally marketed foods’, ‘nutritionally marketed foods’ and ‘nutritionally engineered foods’. Nutritionally engineered foods are defined as foods that have had their nutrient profiles deliberately modified. Nutritionally marketed foods are defined as foods that are marketed with nutrient-content claims, and which therefore only imply particular health benefits. Functionally marketed foods are defined as foods that are explicitly promoted with health claims or as having a beneficial effect on particular bodily functions. Some foods may of course be represented in all three food categories. Other food categories that will be introduced here are transnutric foods and nutrigenomically marketed foods.