Orange, lemon, mandarin, the pulp of these citrus fruits is a rich source of vitamin C, folate, fiber and antioxidant substances. And what about the peel? We often do not think about how important the peel is because we are used to throw it away, but various scientific researches testify that the peel of citrus fruits is a powerful anticancer, antioxidant, anti-inflammatory and capable of promoting the apoptosis of sick cells. This is also what emerges from a very recent review published in the journal Current Developments in nutrition by an Australian team that tried to take stock of the situation (Koolaji et al, Curr Dev Nutr, May 2020).
The peel of citrus fruits provides carotenes, essential oils, pectin and flavonoids, which are powerful antioxidant substances. In particular, among the different types of flavonoids, the peel of mandarins, lemon and oranges contains quercetin, rutin, naringenin, hesperidin but also kaempferol and catechins. It is precisely these substances that give the peel of citrus fruits anticancer and antimetastatic properties thanks to different mechanisms of action, such as the ability to counteract the formation of new blood vessels, which can bring nourishment to the tumor, or to promote the apoptosis, namely the programmed death, of cancer cells, but also thanks to a powerful anti-inflammatory or antioxidant action. In fact, it emerged that the peel of the mandarin has reduced the number of cancer cells in case of leukemia, the peel of the orange has shown to be protective at the level of the liver, where a reduced growth of cells with degeneration was observed, while the peel of the bitter orange was able to reduce metastases and to act in the lungs by counteracting degeneration.
Other studies will have to follow to investigate the action of citrus peel extracts, especially in view of a possible development of future anticancer treatments. In the meantime, a grated lemon or orange peel, of organic origin, on the fruit salad or some strips of mandarin peel added to the morning yogurt are very healthy choices to combat cell degeneration. However, a clarification is required. We are not talking about foods capable by themselves of healing cellular degeneration, maybe in the future medicine will be able to develop effective treatments starting from these substances but at the moment this is not the case. Citrus peels should be seen as one more piece of the extraordinary puzzle of prevention that also passes through diet.