For the first time, scientists report a link between eating nuts and higher levels of serotonin in the bodies of patients with metabolic syndrome (MetS), who are at high risk for heart disease. Serotonin is a substance that helps transmit nerve signals and decreases feelings of hunger, makes people feel happier and improves heart health. It took only one ounce of mixed nuts (raw unpeeled walnuts, almonds and hazelnuts) a day to produce the good effects. The report appears in ACS’ Journal of Proteome Research.  Symptoms of MetS include excess abdominal fat, high blood sugar and high blood pressure, which increase the risk of developing type 2 diabetes and heart disease. Dietary changes may help patients shed the excess weight and become healthier, among the changes, the regular consumption of nuts — which are jam-packed with healthful nutrients, such as healthy fats (unsaturated fatty acids) and antioxidants (polyphenols) — have been recommended to fight the metabolic abnormalities associated with MetS.