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. 2015 Apr 1;146(4):920S-927S.
doi: 10.3945/jn.115.218487.

Protective Effects of the Mediterranean Diet on Type 2 Diabetes and Metabolic Syndrome

Jordi Salas-Salvadó  1   2 , Marta Guasch-Ferré  1   2 , Chih-Hao Lee  3 , Ramón Estruch  2   4 , Clary B Clish  5 , Emilio Ros  2   6
Affiliations

Protective Effects of the Mediterranean Diet on Type 2 Diabetes and Metabolic Syndrome

Jordi Salas-Salvadó et al. J Nutr. .

Abstract

Several studies provide evidence supporting a beneficial effect from the traditional Mediterranean diet (MedDiet) on the risk of type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS). This review summarizes the current scientific evidence from epidemiologic studies and clinical trials on the relation between the MedDiet and T2DM and MetS and the possible mechanisms underlying the reported associations. A recent meta-analysis of prospective cohort studies showed that greater adherence to the MedDiet was associated with a significant reduction in the risk of diabetes. The MedDiet has also been found to be beneficial in the prevention of gestational diabetes. Four large prospective studies have observed inverse associations between the MedDiet and MetS or its components. Few randomized controlled trials (RCTs) have evaluated the effect of the MedDiet on T2DM and MetS. Results from the landmark PREvención con DIeta MEDiterránea (PREDIMED) nutrition intervention trial showed that participants assigned to the MedDiet had a significant 30% reduction in the risk of T2DM and that it also promoted the reversion of MetS and its components, hyperglycemia and central obesity. In addition, 5 RCTs showed the beneficial effects of the MedDiet compared with other dietary patterns on glycemic control in patients with T2DM. A recent meta-analysis of RCTs revealed that, compared with a variety of control diets, the MedDiet was associated with beneficial effects on all MetS components. Bioactive components of the MedDiet synergize to affect various metabolic pathways, leading to a reduced cardiometabolic disease risk. The abundance of healthy, nutrient-dense foods that make up the plant-based MedDiet predicts its bioactivity and potential to beneficially influence metabolic pathways that lead to MetS and T2DM, as well as other chronic conditions. Abundant epidemiologic and clinical trial evidence supports the role of the MedDiet on the prevention and management of T2DM and MetS.

Keywords: Mediterranean diet; cardiovascular disease; diabetes; metabolic syndrome; metabolic syndrome components; review.

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Conflict of interest statement

Author disclosures: JS-S has received grants from the International Nut and Dried Fruit Foundation and is a nonpaid member of the scientific advisory board of the International Nut and Dried Fruit Foundation. ER has received grants from the California Walnut Commission and is a nonpaid member of its scientific advisory committee. MG-F, C-HL, RE, and CBC, no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Consumption of Mediterranean foods improves cardiometabolic health because of their rich composition in bioactive nutrients and phytochemicals and their synergizing effects on metabolic pathways. The main nutrients of the MedDiet are shown along with their principal biological targets (arrow connections). The net effects on intermediate markers of cardiometabolic disease risk shown for these nutrients and their parent foods in clinical trials include the lowering of cholesterol and TGs, increased HDL cholesterol, improved glycemic control, decreased blood pressure, reduced adiposity, and antioxidant and anti-inflammatory actions. The overall result is reduced MetS and type 2 diabetes mellitus risk, as suggested for most of the MedDiet in observational cohort studies and the PREvención con DIeta MEDiterránea trial. See text for details. CHO, carbohydrate; EVOO, extra-virgin olive oil; GI, glycemic index; HDL-C, HDL cholesterol; MedDiet, Mediterranean diet; MetS, metabolic syndrome; TC, total cholesterol; Vegs., vegetables. Adapted from reference with permission.
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