Study suggests new benefits of eating nuts for patients with metabolic syndrome

The article, published in the Journal of Proteome Research,  is authored by Cristina Andrés-Lacueva, Sara Tulipani (first author), Rafael Llorach and Mar Garcia-Aloy, from the University of Barcelona's Department of Nutrition and Bromatology, Olga Jaúregui, from the Scientific and Technical Services (CCiTUB), and the experts Jordi Salas Salvadó, Patricia López-Uriarte and Mónica Bullo, from Rovira i Virgili University (URV) and the Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (CIBERobn), which is part of the Carlos III Health Institute in Madrid.

The study reports the first application of metabolomic techniques to analyse the effects of diet on metabolic syndrome patients. The disease, estimated by the World Health Organization to affect 20% of the adult population, is related to inflammation and oxidative stress and increases the risk of type-2 diabetes and cardiovascular disease. In Catalonia, as in the United States, the prevalence of metabolic syndrome is close to 25% in adults. In Spain as a whole, in children with moderate obesity the prevalence is 17% (compared to 33% for the same population group in the UK).

The clinical part of the study, carried out by the URV's Human Nutrition research group, used two patient groups: one given a diet rich in nuts (specifically, walnuts, almonds and hazelnuts), the other given a diet containing no nuts at all.

As noted by Cristina Andrés-Lacueva, head of the UB's Biomarkers and Nutritional and Food Metabolomics research group and coordinator of the experimental work for the study, "Metabolomics involves the quantitative, multiparametric measurement of human response to a pathophysiological stimulus. It enables us to take a new approach to biochemical and biomedical research, as it is not tied to restricted hypotheses. Metabolomics allows us to identify small alterations in metabolism and homeostasis and broadens the range of possible results thanks to the capacity to detect new markers that could indicate the risk of certain diseases and overall changes in the patient's state of health." Health benefits of a nut-rich diet The scientists behind the study analysed the wide spectrum of compounds excreted in urine and found evidence of various significant changes following nut consumption.

Patients given the nut-rich diet produced a higher level of metabolites derived from the metabolism of tryptophan and serotonin, fatty acids and polyphenols, giving more weight to the hypothesis that these molecules could be at the root of certain health benefits observed in other studies. "It we look at the results for the two patient groups," says researcher Sara Tulipani, "we find significant differences in the levels of these biomarkers. What we do not yet know is the percentage of the metabolite level detected in urine that is stimulated endogenously or exogenously by the patients' metabolism, and whether these metabolites have a direct or indirect role in the health benefits of nut consumption." Improve dietary habits to prevent disease In the field of food science, many studies focus on the importance of dietary changes in preventing metabolic alterations.

The new article provides the first results outlining the health benefits of nut consumption through the reduction of substances associated with inflammatory processes and other cardiovascular risk factors in patients with metabolic syndrome. This area of research could be extended in future work to include other nut varieties and a broader population sample (for example, subjects with diabetes, obesity, etc). "In food and dietary studies, the focus is always prevention. If we look specifically at this new research, we are not talking about a particular drug or introducing dietary supplements but simply replacing once source of fats with another, in this case nuts," explains Dr. Jordi Salas-Salvadó.

The UB's Biomarkers and Nutritional and Food Metabolomics research group, which contributes to the Fun-C-Food Consolider Project and is a member of the Food-Omics Network, works primarily with metabolomics, a key technique in the area of systems biology. The group, an active participant in international collaborations, focuses its research on the search for new robust, safe and sensitive biomarkers, based on analysis of their bioavailability and activity and the consumption of specific foodstuffs (consumption markers), and the simultaneous examination of different metabolic routes to determine their association with obesity, aging and reduced risk of cardiovascular disease (disease risk markers).