“The word “superfood” is a marketing term that has no rigorous scientific meaning. It is generally applied to foods that are unusually high in some nutrient that is considered particularly important to health. Examples include blueberries, which are rich in vitamin C; chia seeds, which contain a lot of omega-3 fatty acids that help your heart; and kale, which has lots of glucosinolates, pungent chemicals tentatively proposed to offer some protection against cancer.” (Marshall, p.38).

Reference

Marshall, M. (2020) Kelp is on the Way. New Scientist. 16 May 2020, pp.36-39.