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11 May 2022

3 min read

Mediterranean diet linked to better kidney function

The results published this month of a study led by the URV-IISPV-CIBERobn Nutrition Unit research group suggest that closely following the Mediterranean diet is associated with better kidney function.

The key seems to lie in achieving higher values for the body’s glomerular filtration rate, reports Spanish website Mercacei.com.

Deteriorating kidney function is a common problem among older people and can trigger chronic kidney disease, which is characterised by decreased glomerular filtration by the kidney and/or high levels of albumin in the urine, a protein found in the blood.

Other risk factors include obesity, hypertension, diabetes and cardiovascular disease. Interest in chronic kidney disease has increased in recent years, as it has a major impact worldwide and affects some 700 million people.

Among modifiable and lifestyle-related risk factors, diet appears to play a crucial role in maintaining kidney function and controlling the progression of CKD. However, most of the previous research related to this topic has focused only on specific nutrients or food groups and not on dietary patterns.

Moreover, the few studies evaluating specific dietary patterns, such as the Mediterranean diet or the DASH (Dietary Approach to Stop Hypertension) diet, showed some discrepancies in their results.

The researchers of the URV-IISPV-CIBERobn and PREDIMED-Plus study focused instead on the association between adherence to the Mediterranean diet – assessed by two different indices – and the DASH diet, and changes in renal function after one year of follow-up.

They also assessed the association between adherence to a protein pattern, using the Protein Diet Score, and kidney function. The Protein Diet Score is an index ranging from 0 to 20 points, depending on total protein intake and plant/animal protein ratio.

After analysing data from 5,675 participants, only a shift towards greater adherence to the Mediterranean diet, as assessed by a 17-item questionnaire, was associated with less deterioration in kidney function, based on glomerular filtration rate.

People with greater adherence to this dietary pattern had a 38% lower risk of a decline in filtration rate greater than or equal to 10%. Conversely, greater adherence to a protein pattern was associated with a worsening glomerular filtration rate.

The researchers further examined the association between each of the different items or questions cited in the 17-item “Mediterranean energy-reduced diet” questionnaire. They found that consumption of vegetables, legumes and wine, as well as traditional Mediterranean tomato sauce and olive oil (sofrito) were associated with better kidney function.

The authors, building on previous scientific evidence, suggest that these foods are rich in beneficial nutrients such as fibre, antioxidants and some anti-inflammatory compounds, which may play a protective role for the kidneys by reducing systemic inflammation, improving endothelial function, lipid profile, insulin resistance, preserving blood pressure and modulating glycaemic index and load, all recognised risk factors for kidney dysfunction.

This work, published this month in the European Journal of Nutrition, was carried out by the predoctoral researcher Cristina Valle-Hita and led by Nerea Becerra-Tomás, postdoctoral researcher at Imperial College London and collaborator at the Human Nutrition Unit (URV); Nancy Babio, researcher and associate professor at the URV; and Andrés Díaz-López, Serra Hunter researcher at the URV. The entire team is part of the Pere Virgili Health Research Institute (IISPV) and the CIBERobn.

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