November 3/London/Daily Mail -- A handful of nuts a day can keep hunger at bay and beat belly fat, according to scientists.

This is the first time a link between eating nuts and higher levels of serotonin -- a substance that decreases appetite, boosts happiness and improves heart health -- has been detected.

Researchers from the University of Barcelona say that it only took one ounce of raw and unpeeled walnuts, almonds and hazelnuts a day to produce the positive health effects.

It is hoped the findings, published in the Journal of Proteome Research, will benefit patients with metabolic syndrome (MetS) which is characterized by excess abdominal fat, high blood sugar and high blood pressure.

Dietary changes along with the regular consumption of nuts, which contain healthy fats and antioxidants, may help patients shed excess weight, decreasing the risk of developing type 2 diabetes and heart disease.

The team led by Cristina Andris-Lacueva in collaboration with the Human Nutrition Unit of the Rovira i Virgili University said, “An increased excretion of serotonin metabolites was associated for the first time with nut consumption.”

During the study, scientists put 22 MetS patients on a nut-enriched diet for 12 weeks and compared them to another group of 20 patients who were following a nut-free diet.

Compounds excreted in the patients' urine were then examined.

Those consuming 30g of mixed nuts a day displayed higher serotonin levels.

Approximately 90% of the body's serotonin is located in the gut, while the remainder is found in the central nervous system where it regulates mood and appetite.

Most prescribed drugs used to treat conditions such as depression, anxiety disorder and social phobia treat are designed to alter serotonin levels.

Meanwhile, a study by the United States Department of Agriculture (USDA), published in the British Journal of Nutrition earlier this year also found that pistachios can help weight loss and support a healthy heart.

Lead researcher David Baer said, “Pistachios convey a variety of health benefits, including weight management support and cardiovascular support.”

He added that the findings contradict the “common misperception to exclude nuts from the diet to reduce caloric intake.”

 From the November 4, 2011, Prepared Foods' Daily News.