In the last century, thanks to scientific advances, life expectancy has increased. However, chronic diseases such as diabetes, CVD and cancer have also increased their incidence in the population. This higher incidence of chronic diseases is largely due to poor lifestyle, especially dietary habits. The Mediterranean diet (MD) and olive oil are known for its beneficial health effects, notably anti-inflammatory, and as a strategy for primary and secondary prevention for these chronic diseases. As this review reflected, despite all the available evidence in support of the MD, its high palatability and good adherence, health practitioners are not routinely prescribing it due to multiple factors such as lack of training and resources as well as lack of evidence in non-Mediterranean populations. This review of the multiple benefits of MD highlighted the need to apply the evidence to clinical practice, a pending issue of vital importance for disease prevention and healthy aging. In the same line, a recent randomized clinical trial studied the anti-inflammatory effect of MD on intestinal permeability. People with chronic diseases, by several mechanisms, have a decreased intestinal barrier integrity, which leads to a sustained state of inflammation that potentiates and aggravates cardiometabolic diseases, diabetes or cancer. In this study, the intervention group adhered to the MD pattern in order to demonstrate the beneficial effect of dietary fiber on the gut barrier. After 3 months of intervention, an increased in short-chain amino acids, produced by bacterial metabolism of dietary fiber, and a decreased in biomarkers related to loss of intestinal permeability were observed. Thus, the article concluded that a MD intervention improved intestinal permeability and provided new solid evidence for the MD recommendation in chronic diseases.