The research, published in the Journal of Proteome Research, reports a link between eating nuts and higher levels of serotonin in the bodies of patients with metabolic syndrome (MetS). The Spanish researchers found that just one ounce of mixed nuts – raw unpeeled walnuts, almonds and hazelnuts – a day resulted in increased excretion of serotonin metabolites in the urine.
“Urinary markers of serotonin metabolism were ... associated, for the first time, to nut consumption, although their endogenous versus exogenous (dietary) origin remains to be elucidated,” said the researchers, led by Cristina Andrés-Lacueva from the Biomarkers & NutriMetabolomics Research Group of the University of Barcelona, Spain.
The researchers pointed out that the study provides the first evidence in humans of the beneficial effects of nut consumption in reducing levels of substances in the body associated with inflammation and other cardiovascular risk factors in patients with metabolic syndrome.
“Because of the important role of serotonin in the regulation of energy balance, metabolism, and glucose homeostasis, attention should also be given in the future to the eventual effects of nut intake on the serotonemic status of subjects with MetS,” they said.
Andrés-Lacueva and her team explained that the rise in obesity around the world means more and more patients are suffering from metabolic syndrome – the symptoms of which include excess abdominal fat, high blood sugar and high blood pressure, all of which increase the risk of developing type 2 diabetes and 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
They added that previous research has suggested that dietary changes – including the regular consumption of nuts – may help patients with MetS shed excess weight, and become healthier. Among the changes nuts have been suggested to correct certain metabolic abnormalities associated with MetS.
To check the biochemical effects of nut consumption, Andrés-Lacueva and her team put 22 MetS patients on a nut-enriched diet for 12 weeks and compared them to another group of 20 patients who were told to avoid nuts.
After analysing a broad spectrum of metabolites excreted in the participants’ urine, the team, found evidence of several healthful changes, including boosted levels of serotonin metabolites in urine – suggesting a role of serotonin in the beneficial effects of nuts.
Increased metabolism and excretion of unsaturated fatty acids were also observed by Andrés-Lacueva and her colleagues. They noted that the finding was “probably attributable to the highly increased intake of PUFA through the consumption of nuts.”
They also reported an increase in urinary microbial and phase II metabolites of nut polyphenols, particularly of urolithins coming from the metabolism of walnut ellagitannins.
“Because of the potential role of urolithins in reducing inflammation and improving cardiovascular health, these microbial metabolites may reasonably contribute to the beneficial effects of nut consumption,” they stated.
Source: Journal of Proteome Research
Volume 10, Issue 11, Pages 5047–5058, doi: 10.1021/pr200514h
“Metabolomics Unveils Urinary Changes in Subjects with Metabolic Syndrome following 12-Week Nut Consumption”
Authors: S. Tulipani, R. Llorach, O. Jáuregui, P. López-Uriarte, M. Garcia-Aloy, M. Bullo, J. Salas-Salvadó, C. Andrés-Lacueva