The effect of whey protein supplementation at breakfast on tryptophan levels, food intake, and mood in postmenopausal women in a 16-week randomized controlled trial

Whey protein isolate supplementation has been recognized as having potential for regulating appetite, thereby potentially improving mood and food intake. The objectives of this project were to 1) analyze the effects of high-quality whey protein intake on overall diet, and 2) identify and examine a correlation between tryptophan levels and mood regulation. This research was conducted using a randomized experimental design. A total of 13 post-menopausal women (12+ months after last reported menstrual cycle) were recruited and allocated to one of two dietary intervention (DI) groups: 1) control (maintain current lifestyle; CON; n = 6), and 2) whey protein isolate (WPI; 25 g; n = 7). Protein was consumed prior to 10:00 am daily. Both interventions were followed daily for 16 weeks. All laboratory visits required participants to arrive fasted with complete 3-day dietary logs. Participants completed the Pittsburgh Sleep Quality Index (PSQI) and Profile of Moods Questionnaire. Height, weight, and waist-to-hip ratio was measured. A blood draw was administered to assess sleep and metabolic blood markers. One-way repeated measures analysis of variance (ANOVA) was used to assess the differences in BMI and POMS. One-way ANOVA was used to calculate the POMS Total Mood Disturbance scores. Clinical biomarker differences were determined through repeated-measures ANOVA (statistically significant: P \u3c 0.05). Prism GraphPad Software Version 9.0 (La Jolla, CA) was used for all analyses. Results were inconclusive. We found no correlation between daily whey protein isolate supplementation and tryptophan levels, overall diet, or mood regulation