Context 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.
Objective To assess the effect of a Mediterranean-style diet on endothelial function
and vascular inflammatory markers in patients with the metabolic syndrome.
Design, Setting, and Patients 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.
Interventions 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%).
Main Outcome Measures Nutrient intake; endothelial function score as a measure of blood pressure
and platelet aggregation response to L-arginine; lipid and
glucose parameters; insulin sensitivity; and circulating levels of high-sensitivity
C-reactive protein (hs-CRP) and interleukins 6 (IL-6), 7 (IL-7), and 18 (IL-18).
Results 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 (P = .22). Mean (SD) body weight decreased more in patients in the intervention
group (−4.0 [1.1] kg) than in those in the control group (−1.2
[0.6] 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 (mean [SD] change, +1.9 [0.6]; P<.001) but remained stable in the control group (+0.2 [0.2]; P = .33). 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).
Conclusion A Mediterranean-style diet might be effective in reducing the prevalence
of the metabolic syndrome and its associated cardiovascular risk.