Mediterranean Diet and the Metabolic Syndrome
Condition: Metabolic Syndrome
MeSH terms: Metabolic Syndrome; Syndrome
Study type: Interventional

Summary: 
      The metabolic syndrome has been identified as a target for dietary therapies to reduce risk
      of cardiovascular disease; however, the role of diet in the etiology of the metabolic
      syndrome is poorly understood. To assess the effect of a Mediterranean-style diet on
      endothelial function and vascular inflammatory markers in patients with the metabolic
      syndrome

      Randomized, single-blind trial conducted from June 2001 to January 2004 at a university
      hospital in Italy among 180 patients (99 men and 81 women) with the metabolic syndrome, as
      defined by the Adult Treatment Panel III.

      Patients in the intervention group (n = 90) were instructed to follow a Mediterranean-style
      diet and received detailed advice about how to increase daily consumption of whole grains,
      fruits, vegetables, nuts, and olive oil; patients in the control group (n = 90) followed a
      prudent diet (carbohydrates, 50%-60%; proteins, 15%-20%; total fat, <30%).

      After 2 years, patients following the Mediterranean-style diet consumed more foods rich in
      monounsaturated fat, polyunsaturated fat, and fiber and had a lower ratio of omega-6 to
      omega-3 fatty acids. Total fruit, vegetable, and nuts intake (274 g/d), whole grain intake
      (103 g/d), and olive oil consumption (8 g/d) were also significantly higher in the
      intervention group (P<.001). The level of physical activity increased in both groups by
      approximately 60%, without difference between groups. Mean body weight decreased more in
      patients in the intervention group (-4.0 kg) than in those in the control group (-1.2 kg)
      (P<.001). Compared with patients consuming the control diet, patients consuming the
      intervention diet had significantly reduced serum concentrations of hs-CRP (P = .01), IL-6 (P
      = .04), IL-7 (P = 0.4), and IL-18 (P = 0.3), as well as decreased insulin resistance
      (P<.001). Endothelial function score improved in the intervention group but remained stable
      in the control group. At 2 years of follow-up, 40 patients in the intervention group still
      had features of the metabolic syndrome, compared with 78 patients in the control group
      (P<.001).

      A Mediterranean-style diet might be effective in reducing the prevalence of the metabolic
      syndrome and its associated cardiovascular risk.
    

Detailed description: 
      Patients consuming the intervention diet were given detailed advice about the usefulness of
      the experimental diet. Through a series of monthly small-group sessions, intervention
      patients received education in reducing dietary calories (if needed), personal goal-setting,
      and self-monitoring using food diaries. Behavioral and psychological counseling was also
      offered. The dietary advice was tailored to each patient on the basis of 3-day food records.
      The recommended composition of the dietary regimen was as follows: carbohydrates, 50% to 60%;
      proteins, 15% to 20%; total fat, less than 30%; saturated fat, less than 10%; and cholesterol
      consumption, less than 300 mg per day. Moreover, patients were advised to consume at least
      250 to 300 g of fruits, 125 to 150 g of vegetables, and 25 to 50 g of walnuts per day; in
      addition, they were also encouraged to consume 400 g of whole grains (legumes, rice, maize,
      and wheat) daily and to increase their consumption of olive oil. Patients were in the program
      for 24 months and had monthly sessions with the nutritionist for the first year and bimonthly
      sessions for the second year. Compliance with the program was assessed by attendance at the
      meetings and completion of the diet diaries.
    

Intervention name(s): Mediterranean diet; Control
Intervention type(s): Behavioral; Behavioral
Intervention description(s): The dietary advice was tailored to each patient on the basis of 3-day food records. The recommended composition of the dietary regimen was as follows: carbohydrates, 50% to 60%; proteins, 15% to 20%; total fat, less than 30%; saturated fat, less than 10%; and cholesterol consumption, less than 300 mg per day. Moreover, patients were advised to consume at least 250 to 300 g of fruits, 125 to 150 g of vegetables, and 25 to 50 g of walnuts per day; in addition, they were also encouraged to consume 400 g of whole grains (legumes, rice, maize, and wheat) daily and to increase their consumption of olive oil.; Patients consuming the control diet were given general oral and written information about healthy food choices at baseline and at subsequent visits but were offered no specific individualized program. However, the general recommendation for macronutrient composition of the diet was similar to that for the intervention group (carbohydrates, 50%-60%; proteins, 15%-20%; and total fat, <30%).
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Metabolic syndrome; Mediterranean diet; Inflammatory markers; Endothelial function