The term ‘functional foods’ was first used in Japan to refer to foods with added ingredients that claim to provide a health benefit to consumers beyond the benefits provided by ordinary foods themselves. Examples include probiotic yogurts, cholesterol-lowering spreads and foods with added nutrients, such as omega-3 fatty acids. Such products have also been referred to as “nutraceuticals” or “designer foods.” The Japanese government instituted an approval system for functional foods in 1991.

Although functional foods in the original sense were those modified by the addition of specific nutrients, the term is also sometimes applied to conventional foods such as grains, fruits, fish, vegetables and nuts.  However, for these foods, the description has somewhat fallen out of favour in popular parlance, replaced by the term “superfoods”. Over past years these have included blueberries, salmon, kale, acai, goji berries and chia seeds. Scientists tend to reject the “superfood” claim as merely a marketing ploy, although a number of these foods have well-documented health benefits.

The concept of functional foods, when it was first developed in Japan, had a specific purpose. This was to improve the health of an ageing population. Eligible foods carried a special seal, and are now recognised as Foods for Specified Health Use (FOSHU). By early 2019, total FOSHU approvals in Japan numbered 1,063 and a new category known as New Functional Foods had been introduced. Europe has much stricter regulations for foods making health claims.

A paper published in the Journal of Nutrition cited various definitions of functional foods, including that of the  National Academy of Sciences’ Food and Nutrition Board:  “any modified food or food ingredient that may provide a health benefit beyond the traditional nutrients it contains”.  There is evidence for the health benefits of some of these products. For example, margarines with added plant sterols have been shown to reduce total and LDL cholesterol.  However, many of the claims for these foods are not supported by reliable clinical trials. Often, the amount of the additive you need to consume to obtain a benefit is far beyond what’s feasible.

Genetic modification has opened the door to a whole new range of functional foods. One article on the future of food cites potatoes, corn and rice containing more protein; linseed having more omega-3 and omega-6 fats; tomatoes containing antioxidants originally found in snapdragons; and lettuce that carries iron in a form that’s easily digestible by the body.