Metabolic syndrome is a cluster of risk factors (including glucose intolerance, obesity, hypertension, high triglycerides and low HDL cholesterol) that greatly increases one's risk of developing heart disease.
In summary, this recent study adds more credence to the idea that the longstanding controversy regarding "low-fat vs. low-carb" is finally resolving into the conclusion that neither extreme is completely right or completely wrong. Rather, a diet that incorporates good fats and good carbs (and avoids bad fats and bad carbs) actually appears to be optimal for heart health. And of all the popular diets being advanced these days, the Mediterranean diet appears to come the closest to embodying those healthful elements.
Kastorini CM, Milionis HJ, Esposito K, et al. The effect of Mediterranean diet on metabolic syndrome and its components. J Am Coll Cardiol 2011; 57:1299-313.