They blurred the distinction between foods and drugs. Although there is no universally accepted definition for these, the term & concept functional foods came from Japan in early 1980s in response to their growing health care costs. The functional foods may also include conventional foods such as grains or modified foods such as yogurt.
Here nature is also playing its part and provided us the clues to identify the foods what they are good for such as walnuts having two hemispheres tells us these are good for brain. Sliced tomatoes resemble the heart chambers, so are helpful in reducing cardiovascular risk. Carrots are good for eyes and sliced carrots mimics the picture of an iris and pupil to indicate they are good for eyes. This list goes on such as celery for bones or avocados for uterus.
There are also foods that can make us slimmer, smarter, whitens our teeth or decrease our stress. The modern concept of different teas such as peppermint tea, chamomile tea is nothing less than functional foods where these can help in homeostasis of ayurvedic body pillars such as ‘vata’, ‘pitta’ or ‘kapha’. In this, the coolness of chamomile can help to cool the aggravating pitta or peppermint tea can refresh the kapha.
Therefore, functional foods always exist. These are not just invented.
References
Hasler, C. M. (2002). Functional foods: benefits, concerns and challenges—a position paper from the American Council on Science and Health. The Journal of nutrition, 132(12), 3772-3781. https://doi.org/10.1093/jn/132.12.3772
Devine, C., & Jensen, W. K. (2004). Functional Foods. Encyclopaedia of meat sciences, 1, 492-499. https://doi.org/10.1016/B978-0-12-384731-7.00172-0
Vainio, H., & Mutanen, M. (2000). Functional foods—blurring the distinction between food and medicine. Scandinavian Journal of Work, Environment & Health, 178-180. https://doi.org/10.5271/sjweh.528