Phytochemicals in cancer prevention and management

Phytochemicals are compounds found in plants, which are responsible for the colour, taste and aroma of foods. Over and above these pleasant attributes, they protect us from environmental and ingested carcinogens by arming our antioxidant enzymes, enhancing DNA repair pathways and have direct effects on the fundamental hallmarks of cancer progression and metastasis. It is not a surprise then that analysis from the World Cancer Research Fund and other academic bodies, report that individuals eating phytochemical-rich foods have a lower risk of cancer or relapse after treatments. The debate lies in whether concentrating these foods, or elements of these foods, into nutritional supplements may boost their health attributes. One notable randomised controlled trial (RCT) has demonstrated benefits for men with prostate cancer, but other trials of extracted chemicals have shown no benefit or even an increased cancer risk. This article provides a clinical overview, for medical practitioners, of the major classes of phytochemicals with examples of their common food sources. It reviews the international evidence for their anti-cancer mechanisms of action and their clinical benefits, as well as discussing the pros and cons of concentrating them into nutritional supplements.