Evidence to Support the Anti-Cancer Effect of Olive Leaf Extract and Future Directions

Abstract

The traditional Mediterranean diet (MD) is associated with long life and lower prevalence of cardiovascular disease and cancers. The main components of this diet include high intake of fruit, vegetables, red wine, extra virgin olive oil (EVOO) and fish, low intake of dairy and red meat. Olive oil has gained support as a key effector of health benefits and there is evidence that this relates to the polyphenol content. Olive leaf extract (OLE) contains a higher quantity and variety of polyphenols than those found in EVOO. There are also important structural differences between polyphenols from olive leaf and those from olive fruit that may improve the capacity of OLE to enhance health outcomes. Olive polyphenols have been claimed to play an important protective role in cancer and other inflammation-related diseases. Both inflammatory and cancer cell models have shown that olive leaf polyphenols are anti-inflammatory and protect against DNA damage initiated by free radicals. The various bioactive properties of olive leaf polyphenols are a plausible explanation for the inhibition of progression and development of cancers. The pathways and signaling cascades manipulated include the NF-κB inflammatory response and the oxidative stress response, but the effects of these bioactive components may also result from their action as a phytoestrogen. Due to the similar structure of the olive polyphenols to oestrogens, these have been hypothesized to interact with oestrogen receptors, thereby reducing the prevalence and progression of hormone related cancers. Evidence for the protective effect of olive polyphenols for cancer in humans remains anecdotal and clinical trials are required to substantiate these claims idea. This review aims to amalgamate the current literature regarding bioavailability and mechanisms involved in the potential anti-cancer action of olive leaf polyphenols.

Chemopreventive role of olive oil in colon carcinogenesis by targeting noncoding RNAs and methylation machinery

“…Recently, Boss et al . have provided shreds of evidence that olive oil and its polyphenols have an anti‐inflammatory role in various diseases via inhibiting NF‐κB activation . Therefore, our data further validate the above findings in context with colon carcinogenesis wherein olive oil administration prevents inflammatory cascade via inhibiting NF‐κB activation in a chronic inflammatory disease like colorectal cancer.…”

Oleuropein Decreases Cyclooxygenase-2 and Interleukin-17 Expression and Attenuates Inflammatory Damage in Colonic Samples from Ulcerative Colitis Patients

“…Since data have been produced to show that OLE may significantly inhibit the activation of NF-κB along with the production of TNF-α and IL-1β [30,31], it may be argued that, in our setting, the OLE-induced inhibition of COX-2 activity may be mediated through the suppression of these factors.…”

Effect of drying method on oleuropein, total phenolic content, flavonoid content, and antioxidant activity of olive (Olea europaea ) leaf

“…Several studies have evaluated the effect of olive leaf extracts in treatment of various diseases such as cardiovascular diseases (Lockyer, Rowland, Spencer, Yaqoob, & Stonehouse, ), cancer (Boss, Bishop, Marlow, Barnett, & Ferguson, ), and myocardial oxidative damage and atherosclerosis (Efentakis et al, ). Moreover, anti‐HIV activity of olive leaf extract was proved by modulation of host cell gene expression by HIV‐1 infection (Lee‐Huang, Zhang, Huang, Chang, & Huang, ).…”