Previous studies have linked inclusion of nuts in the diet to heart health, weight loss, and reduction in the risk for type 2 diabetes. Now, for the first time, a study documents the metabolic and biochemical changes occurring after eating nuts. Researchers were surprised to find that nut consumption increases levels of serotonin in the body. Substances associated with inflammation and cardiovascular risk were also reduced.
Nutrients in nuts
Nuts contain protein, fiber, omega-3 fatty acids, and good fats such as mono- and poly-unsaturated fatty acids. They contain no cholesterol. Although nuts are high in fat content, the fats are mostly the good kind. Nuts also contain minerals such as magnesium, phosphorus, and manganese. Almonds are rich in vitamin E and peanuts are rich in folate, a B vitamin. Choose unsalted nuts for beneficial health effects.
Serotonin
Serotonin is a neurotransmitter that relays messages within the brain and also affects muscles, the cardiovascular system, and other tissues. It is synthesized from the amino acid tryptophan in the brain and the intestines with more than 90 percent of synthesis occurring in the intestines. Serotonin regulates mood, appetite, obesity, high blood pressure and depression. The serotonin reuptake inhibitors prescribed for depression increase the concentration of serotonin in the brain.
The study
Obesity causes more and more people to develop metabolic syndrome, which is a pre-diabetic disorder. Metabolic syndrome is a risk factor for type 2 diabetes and heart disease and is associated with abdominal fat, high blood pressure and high blood sugar. Researchers at the University of Barcelona and Rovia I Viegili University put 22 individuals with metabolic syndrome on a diet, which included a daily dose of nuts (one ounce). They instructed 20 other patients to avoid nuts. The nuts were a mixture of raw walnuts, hazelnuts, and unpeeled almonds. After 12 weeks, they analyzed the urine for metabolites or degradation products. They found 20 potential metabolites, including antioxidant metabolites, associated with nut intake. They also detected a significant increase in serotonin metabolites, suggesting that nuts increase serotonin concentrations. The researchers write: “The metabolomics approach revealed 20 potential markers of nut intake, including fatty acid conjugated metabolites, phase II and microbial-derived phenolic metabolites, and serotonin metabolites. An increased excretion of serotonin metabolites was associated for the first time with nut consumption” (Tulipani, S. et al.).
Take home message
Eating one ounce (28 grams) of raw nuts, which is equivalent to a handful of nuts, daily, may reduce belly fat, improve mood, and reduce blood pressure and blood sugar in part due to the increase in serotonin. This study provides evidence that diet modification can cause distinct biochemical changes in the body.
Sources
Tulipani,S. et al. Metabolomics Unveils Urinary Changes in Subjects with Metabolic Syndrome following 12-Week Nut Consumption. Journal of Proteome Research (2011) 10: 5047
http://www.sciencedaily.com/releases/2011/11/111102125348.htm
http://nutshealth.com/comparative-table-of-the-nutritive-values-of-nuts.html
http://lancaster.unl.edu/food/ftmar04.htm