Nuts are rich in many bioactive compounds that can exert beneficial
effects on cardiovascular health. We reviewed the evidence relating
nut consumption and the metabolic syndrome (MetS) and its components.
Nuts reduce the postprandial glycemic response; however,
long-term trials of nuts on insulin resistance and glycemic control in
diabetic individuals are inconsistent. Epidemiologic studies have
shown that nuts may lower the risk of diabetes incidence in women.
Few studies have assessed the association between nuts and abdominal
obesity, although an inverse association with body mass index
and general obesity has been observed. Limited evidence suggests
that nuts have a protective effect on blood pressure and endothelial
function. Nuts have a cholesterol-lowering effect, but the relation between
nuts and hypertriglyceridemia and high-density lipoprotein
cholesterol is not well established. A recent pooled analysis of clinical
trials showed that nuts are inversely related to triglyceride concentrations
only in subjects with hypertriglyceridemia. An inverse association
was found between the frequency of nut consumption and the
prevalence and the incidence of MetS. Several trials evaluated the
effect of nuts on subjects with MetS and found that they may have
benefits in some components. Compared with a low-fat diet, a Mediterranean
diet enriched with nuts could be beneficial for MetS management.
The protective effects on metabolism could be explained by
the modulation of inflammation and oxidation. Further trials are needed
to clarify the role of nuts in MetS prevention and treatment.