Background: The correlation between obesity and depression is well established. Tryptophan (Trp) is an essential amino acid that acts as substrate for serotonin and melatonin biosynthesis, both know to play a role in satiety, anxiety, and depression. Furthermore, low plasma Trp levels have been associated with obesity.
Objective: To investigate the effects of Trp supplementation as a conjunctive therapy to conventional life-style intervention on weight loss and psychological wellbeing.
Methods: Randomised double-blind placebo-controlled clinical trial with parallel groups. Obese children (BMI 24 SDS) ages 1217 were assigned to either Trp supplementation (3.5 mg/kg per day) or placebo as a conjunctive therapy to the conventional life-style intervention. Both groups received nutritional education, behavioral counseling and exercise recommendations of equal intensity throughout the 6 months intervention. The study was conducted at a university hospital and was approved by the Institutional Review Board.
Results: 43 patients were enrolled and 40 completed the study (19 assigned to Trp group and 21 to placebo). There were no significant differences on the baseline characteristics between study groups. After a 6 months intervention both groups showed a significant reduction in BMI z-score and total caloric intake (P<0.01). BMI reduction tended to be greater in the tryptophan group (ΔBMI z-score −0.33±0.05 in Trp vs −0.20±0.05 in placebo, P=0.078). Trp supplementation improved depression and anxiety scores, based on IDER and CMAS-R scale (P<0.05), suggesting an impact on psychological wellbeing. No significant differences between groups were found for other variables.
Conclusion: In our study Trp supplementation in obese adolescents in conjunction with life-style intervention improved some aspects of psychological wellbeing and showed a tendency to greater weight loss with no significant effect on caloric intake. Given our results and the lack of successful treatments, further studies are needed.
Funding: Fondo Investigaciones Sanitarias del Instituto de Salud Carlos III (EC10-148).
01 Oct 2015 - 03 Oct 2015