Foods and Nutrients as Adjuvants in Cancer Chemo-prevention and Treatment

Foods and nutrients may be useful sources in preventing and treating cancer. Substances like resveratrol, curcumin, pomegranate and honey have turned out to be much promising agents for combating tumor cells, especially for overcoming chemoresistance. Compounds like resveratrol, which is abundant in red wine, red grapes, blueberries, peanuts and pistachios seem to induce p53-dependent apoptosis. Identification of a receptor of resveratrol in tumor cells, supports the potential of this substance as an anti-cancer agent. This receptor could serve in studies of future resveratrol analogues. Resveratrol is documented to surpass chemo-resistance through inhibition of NF- κB as well as the STAT3 pathway. Resveratrol has shown much promise in preclinical trials and because of its good safety profile it may be an ideal chemo-preventive and chemotherapeutic agent. Curcumin, a yellow component which belongs to the superfamily of polyphenols, is the most potent substance of turmeric, an Indian spice derived from the Curcuma longa plant. Curcumin and its analogues deploy their anti-tumor effects by inhibiting the STAT3 and the NF-κB, which play pivotalroles in the evolution of tumor cells. Furthermore, it has been demonstrated to inhibit focal adhesion kinase (FAK) phosphorylation and enhance the expressions of several extracellular matrix components, which play a pivotal role in invasion and metastasis. Curcumin has been shown to enhance cell adhesion ability, through induction of extracellular matrix substance collagen, fibronectin, and laminin. Taken together, it is suggested that curcumin suppresses FAK activity by means of inhibition of its phosphorylation sites and also induces extra-cellular matrix components to enhance cell adhesion ability, thus, preventing detachment of cancer cells and cell migration. Honey comprises of vitamins, including ascorbic acid, pantothenic acid, niacin and riboflavin and minerals like calcium, copper, iron, magnesium, manganese, and phosphorus. Also, honey is suggested to exhibit anti-cancerous features, while its antiproliferative and apoptotic effects vary according to the “floral origin and the phenolic content”. Finally, the role of pomegranate juice and/or pomegranate extracts in preventing and treating various tumors, especially prostate cancer will be discussed in this review. The pomegranate fruit is derived from the tree Punica granatum and is cultivated in Mediterranean countries, Russia, India, China, Japan, and the United States. The anti-oxidant properties of pomegranates have been demonstrated to be better compared to red wine or green tea, two dietary compounds which have been promising in preclinical prostate cancer cell lines for reducing metastasis, mainly through inhibiting matrix substances. The roles of resveratrol, pomegranate, honey as well as curcumin as weapons in our battle against cancer will be further elucidated in this review. Many more studies are needed in order to determine the exact dosage of each of the above-mentioned compounds for the prevention and treatment of various types of cancers, respectively. In this view, bioavailability of those substances has to be improved, whilst the maximum dosage that does not cause any serious adverse effects in humans has to be established. In particular, future studies should focus on ameliorating formulas of the above-mentioned compounds, by improving their absorption and kinetics as well as by minimizing adverse side effects, which are estimated to be often in doses that are really helpful for humans in the clinical setting.

Keywords: Apoptosis, Cancer, Curcumin, Honey, Molecular pathways, Pomegranate, Resveratrol.