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.
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.
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).
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).
A Mediterranean-style diet might be effective in reducing the prevalence
of the metabolic syndrome and its associated cardiovascular risk.