Mushrooms are considered to be functional foods with high nutritional, culinary, and pharmacological values, and there has been an increase in their consumption, both through the diet and in the form of dietary supplements. The present study aimed to briefly review the nutritional composition and biological properties of sixteen mushroom species, as well as to compare the mushrooms’ proximate composition to the analyses conducted at the University of Thessaly, Greece, in cooperation with the Natural History Museum of Meteora and Mushroom Museum. The macronutrient profile of each mushroom was analyzed according to the methods described in the Association of Official Analytical Chemists International, at the School of Agricultural Sciences of the University of Thessaly. The protein content of the mushrooms was found to range between 13.8 g/100 g and 38.5 g/100 g, carbohydrate content ranged between 32 g/100 g and 61.4 g/100 g, and fat content ranged between 0.4 g/100 g and 5.9 g/100 g. Additionally, a serving of 100 g of most species of mushrooms covers 15 to 30% of the daily recommendation of vitamins and trace elements. Based on their compositions, mushrooms were shown to constitute excellent food sources from a nutritional point of view, containing high amounts of dietary fiber and protein, low fat, and reasonable sources of phosphorus, although they were shown to be poor in vitamin C.

Background: Recent research indicates that both endocannabinoids (eCB) and heart rate variability (HRV) are associated with stress-induced experiences. However, these underlying mechanisms are not elucidated. The present study aims to investigate whether exposure to acute and chronic stress conditions can give rise to measurable changes, both to the peripheral eCB ligands and HRV. Methods: Thirteen candidates under intense preparation for their enlistment in the Hellenic Navy SEALs (HNS) participated in the study. All subjects underwent mental state examination, while HRV variables in time and frequency domain recordings were acquired. Furthermore, at baseline and 30 days after prolonged and intensive physical exercise, hair was collected to measure eCB ligands, such as anandamide (AEA), 2-arachidonoylglycerol (2-AG), and the N-acyl ethanolamine (NAE) molecules: palmitoylethanolamide (PEA) and oleoylethanolamide (OEA). Results: Comparing basal hair concentrations of eCB ligands before and after intense physical exercise, we found that AEA, PEA, and OEA were notably increased, whereas no differences were observed regarding the ligand 2-AG. Furthermore, there were observed associations between the concentrations of peripheral eCB ligands, both at baseline and after the prolonged physical exercise and the time and frequency domains of HRV. Conclusions: These findings suggest that endocannabinoid–HRV interrelations might share a short-term, and long-term adaptability of the changes in self-regulation associated with stress. Further studies will be required to determine the validity of peripheral eCB signaling and HRV as a biomarker for different aspects of the stress response.