This study examined the influence of milk casein-derived peptides on cerebral activity after mental stress loading. In a crossover study, 16 male students were given a drink containing peptides (peptide group), or water (control group) before stress loading. The oxyhaemoglobin (HbO 2 ) concentration in the prefrontal area of the brain and work efficiency were measured as indicators of cerebral activity and differences in these parameters were examined according to type A or type B personality. Type A behaviour was defined as: aggression-hostility, hard-drivingtime-urgency and speed-power, whereas type B behaviour did not have these characteristics. Peptide intake resulted in a significant increase in both HbO 2 concentration and work efficiency, whilst a similar increase was not seen in the control group. When divided into type A or type B personality, the changes in HbO 2 concentration for the control group differed significantly in the right prefrontal area. Moreover, in type A subjects the HbO 2 concentration in the right prefrontal area following intake was significantly different between the peptide and control groups.

This study was conducted to clarify the effect of eucalyptus essential oil mixed with milk casein peptide food for human physiological relaxation. Fifteen male university students (21.2 ± 0.9 yr) participated in study as subjects. The subjects were given one of two types of experimental drink (peptide + eucalyptus flavor (Pep + EF), and peptide + grapefruit·orange flavor (Pep + G·O), each flavor contains natural essential oil). We measured the change in salivary cortisol concentration and POMS scores before and two hours after taking experimental drink. The results of a Type A behavior pattern test were used to classify subjects. The concentration of salivary cortisol decreased significantly two hours after taking Pep + EF. And Type B showed bigger change than Type A. In conclusion, the results show that eucalyptus essential oil has the effect of relaxation, and that the effects on Type A and Type B are different.

This study examined the influences of the oral ingestion of casein hydrolysate from bovine milk at rest physiologically and psychologically. Eleven male university students were given a casein hydrolysate drink (H) or a maltitol drink as a control (C) in a crossover study. Just before and one hour after ingestion of each drink, the total-hemoglobin (tHb) concentrations at ten points of the prefrontal cortex to evaluate cerebral activity, and heart rate variability (HRV) to evaluate autonomic nerve activity through spectral analysis were measured as physiological indicators. The Japanese version of the State-Trait Anxiety Inventory-state anxiety (STAI-s) score was also used, as a psychological indicator. In comparison between H and C ingestion, a significant difference is observed only in tHb concentrations at one of ten points. At this point, the change in tHb concentration was lower after H ingestion compared to C ingestion. And in comparison between before and after ingestion of each drink, a significant increase in tHb concentration at two points after C ingestion, a significant increase in parasympathetic activity and decrease in sympathetic activity after H ingestion, and a significant decrease in STAI-s score in H ingestion were observed. These results suggest that ingestion of the casein hydrolysate may keep prefrontal cortex activity stable while maltitol ingestion partially increases the activity. Moreover, there is a possibility that casein hydrolysate might decrease sympathetic activity, increase parasympathetic activity, and lower anxiety. We conclude that the bovine milk casein hydrolysate may have more relaxing effects than maltitol.