To investigate the effects of flavanol-rich cacao extract on healthy middle-aged women’s fatigue and mood conditions, we conducted a randomized, double-blind, placebo-controlled study in women aged 40–60 years who had reported fatigue and had shown high levels of a serum oxidative stress marker. We randomized the participants (n = 60) into equal groups receiving either a beverage containing cacao flavanols (240 mg/200 mL/day) or a placebo for 8 weeks. Before and after the 8-week treatment, we determined the participants’ Chalder fatigue scale (CFS) scores, various mood states, autonomic nervous system (ANS) activity levels, and their ANS balance. The results demonstrated that among the mood states, the indicators of negative mood (e.g., depression, fatigue, and anger) and the total mood disturbance score were significantly lower in the cacao group compared to the placebo group after the treatment (p < 0.05). The change in the index of positive mood (i.e., vigor) from baseline to 8 weeks was significantly higher in the cacao group versus the placebo group (p < 0.05). There were no significant between-group differences in the changes in the CFS score or ANS activity level. The consumption of flavanol-rich cacao extract both suppressed negative moods and promoted positive moods in healthy middle-aged women. These results suggest that cacao flavanols may be a useful food material that can improve variable mood conditions in middle-aged women and support their active lives.

Few studies have demonstrated the suppressive effects of amino acids (AAs) on the level of cortisol during exercise in humans. We hypothesized that an AA mixture containing arginine, which promotes lipid metabolism, valine, which effectively decreases the level of glucocorticoid, and serine, a substrate in the production of phosphatidylserine that is reported to blunt increases in cortisol, would suppress the exercise-induced cortisol response by combining the positive effects of the AAs synergistically. A randomized, double-blinded, placebo-controlled crossover trial was conducted. Twenty healthy recreationally active males ingested either an AA mixture containing 1.8 g of arginine, 1.1 g of valine, and 0.1 g of serine or a placebo. Thirty minutes after ingestion, subjects performed an exercise trial on a cycle ergometer for 80 min at 50% maximal oxygen consumption. Plasma cortisol and other blood parameters immediately before and after the exercise were evaluated. Plasma cortisol concentrations after exercise were significantly higher than those before exercise in the placebo condition (9.51 ± 0.85 vs 14.39 ± 2.15, p < 0.05), while there was no significant difference in the AA condition (9.71 ± 0.93 vs 9.99 ± 1.23, p = 0.846). In addition, the increase in plasma cortisol before and after exercise was significantly lower in the AA condition than in the placebo condition (0.28 [− 2.75, 3.31] vs 4.87 [0.89, 8.86], p < 0.05). For the level of adrenocorticotropin, there was a significant difference between before and after exercise only in the placebo condition (24.21 ± 2.91 vs 53.17 ± 6.97, p < 0.01) but not in the AA condition (27.33 ± 3.60 vs 46.92 ± 10.41, p = 0.057). Blood glucose, plasma lactate, plasma ammonia, serum creatine phosphokinase, serum total ketone body, and serum free fatty acid were also significantly changed by the exercise load in both conditions, but no significant differences were observed between the two conditions. The present study demonstrated that the AA mixture suppressed the cortisol response during exercise without affecting exercise-related biological parameters such as glucose or lipid metabolism. UMIN Clinical Trials Registry, UMIN000023587 . Registered 19 August 2016.