Most foods are considered functional in terms of providing nutrients and/or energy to sustain basic life, but nutraceuticals and functional foods are defined dietary foods that prevent or reverse a diseased state. Nutraceuticals and functional foods are intensively researched for their role in maintaining health and prevention of diseases. Increasing public awareness of the link between diet and health has boosted the consumption of these foods to unparalleled levels, particularly in countries where the population is ageing and health care costs are rising. The science behind these foods is growing rapidly not only because of the increasing number of new substances or type of novel foods, but also the regulatory bodies requiring more and more evidence on efficacy, mode-of-action and safety. The nutraceuticals market is growing rapidly, with a 2016 forecast value of $207 billion, according to a new report available on companiesandmarkets.com. The latest trend in nutraceuticals and functional foods sector has been the recovery of nutraceuticals from discarded fruits and vegetables. For example, a wave of possible new functional ingredients is being developed by the Irish Agriculture and Food Development Authority (Teagasc), some of which are derived from waste products. One of their findings has shown that onion peels, a common by-product of food processing, have a higher antioxidant activity than their flesh. Onions are rich in quercetin, a potent antioxidant, also found in apples, berries and other vegetables. This has opened a completely new research area by deriving the potentially important nutraceuticals and functional foods in much higher concentrations than their principal parts. In fact, this would bring in the verbatim of sustainable nutraceutical and functional food sector by putting the focus on the valuable wastes and their value-addition.