Components of the Mediterranean Diet with chemopreventive activity toward colorectal cancer

Colorectal cancer is one of the leading causes of cancer incidence and death worldwide. For the past 30 years researchers have tried to find drugs suitable for the chemoprevention of the diseases. Epidemiological studies have demonstrated that adherence to the Mediterranean Diet (MD) is protective toward colon cancer development. Key components of this diet are olive oil (OO), fruits and vegetables, legumes and fish. Importantly, many bioactives present in these foods have shown anti-cancer activity in in vitro as well as in animal models of colon carcinogenesis, indicating a possible use as preventive agents. However, when translated to human trials, single bioactives have yielded conflicting results mostly due to irreproducibility of pre-clinical data. Since our preclinical models are usually designed to test single molecules at high concentrations and for very short time in order to provide significant effects, future studies should employ multiple bioactives that would resemble a more natural approach with possible significant synergisms that might be critical for cancer prevention. In this review we will discuss data obtained with components of the MD with a specific focus on OO, omega-3 polyunsaturated fatty acids and apples.