2016
Maurizio Gallieni, MD and Adamasco Cupisti, MD
Chronic kidney disease (CKD) and cardiovascular disease (CVD) share similar risk factors, many of which are closely related to lifestyle. Limited physical activity, smoking, and improper dietary habits are well-known risk factors for CVD, and CVD is directly linked to the development and progression of CKD.
The prevalence of CKD stages 3 to 5 varies across and within countries. In the United States, it ranges from 11.8% in the Midwest to 4.8% in the Northeast. In Europe, the overall prevalence is lower, but again, highly variable, ranging from 5.9% in the Northeast German Study of Health in Pomerania (SHIP) Study to as low as 1% in Italy.
Restricting the analysis to the population aged 45 to 74 years of the same countries, the prevalence of CKD stages 3 to 5 increases to 2% in Italy and to 11.5% in Germany.
Although many factors differ by region, lifestyle and diet often have the greatest variation, suggesting that they may have a significant role in the development and progression of CKD and CVD in addition to other environmental and genetic factors.
The Dietary Approaches to Stop Hypertension (DASH) diet is a dietary pattern promoted by the US National Institutes of Health for prevention and control of arterial hypertension. The DASH diet is rich in fruits, vegetables, whole grains, and low-fat dairy foods; it also includes meat, fish, poultry, nuts, and beans, whereas sugar-sweetened foods and beverages, red meat, and added fats are limited.
When the DASH diet was designed, the chosen nutrition pattern had many similarities with the Mediterranean diet. In 2010, UNESCO (United Nations Educational, Scientific and Cultural Organization)
acknowledged the Mediterranean diet as an “Intangible Cultural Heritage of Humanity”.
Rather than a diet, it is considered a lifestyle, adapting to the different nutritional and socioeconomic contexts of the Mediterranean region. The dietary component includes high consumption of olive oil, legumes, unrefined cereals, fruits, and vegetables; moderate to high intake of fish; moderate intake of dairy products and wine; and low consumption of red or processed meat.
Other components include adequate intake of water and/or herbal infusions, small serving sizes, regular physical activity, adequate rest, conviviality, culinary activities, and use of traditional, local, and eco-friendly products, with attention to seasonality and biodiversity.
Randomized controlled trials, observational studies, and meta-analyses demonstrate that the Mediterranean diet is beneficial for both primary and secondary prevention of CVD; however, no association has been found between the specific foods characterizing the Mediterranean diet and clinical outcomes.
In the randomized controlled PREDIMED (Prevención con Dieta Mediterránea) study, in which no energy restriction and no special intervention on physical activity were applied, the Mediterranean diet supplemented with extra virgin olive oil, compared to a standard control diet with advice on low-fat food, was associated with a significant 30% reduction in CVD events and a 40% reduction in the incidence of type 2 diabetes mellitus during a median follow-up of 4.8 years.
In a cross-sectional study of healthy people, higher adherence to the Mediterranean diet was associated with higher estimated creatinine clearance. Although a randomized controlled trial would be needed to draw more firm conclusions on whether the Mediterranean diet has a protective effect on kidney disease, the complexity of the diet makes designing a high-quality randomized controlled trial difficult.
Critically, other factors are at play given that Spain, with its extensive Mediterranean coast, has an adjusted prevalence of CKD stages 3 to 5 of 7.8% among individuals aged 45 to 75 years, exceeding many Northern European countries, such as Finland (4.5%), Norway (3.3%), and the Netherlands (2.7%).
