Probiotic supplementation for reducing psychological symptoms in cancer patients on chemotherapy: A pilot trial

Psychological disorders, including depression, anxiety, and stress, are prevalent among cancer patients undergoing chemotherapy. Probiotics have been investigated as a potential supplement to modulate the gut–brain axis and improve psychological symptoms, possibly through mechanisms such as serotonin regulation. However, studies on the effects of probiotics on psychological symptoms in chemotherapy patients are limited. This randomised, double-blinded, placebo-controlled pilot trial was conducted at the outpatient clinic of dr. Kariadi Hospital, Semarang, in 2023. Sixty-one cancer patients undergoing chemotherapy were enrolled and randomised into an intervention ( n = 30) and control ( n = 31) group. The intervention group received probiotics ( Lactobacillus rhamnosus Rosell-11 and Lactobacillus helveticus Rosell-52) twice daily for eight weeks. The primary outcomes were changes in depression, anxiety, and stress levels measured by the Depression, Anxiety, and Stress Scale 42 (DASS-42). The secondary outcome was serum serotonin levels. The intervention group showed a significant decrease in total DASS-42 scores ( p = 0.001), indicating an overall reduction in psychological distress. However, changes in the scores of the subscales (depression, anxiety, and stress) were not statistically significant ( p > 0.05). Serum serotonin levels increased in the intervention group, but this was not statistically significant ( p = 0.38). The findings should be interpreted cautiously due to small sample size and potential confounding factors. This pilot study suggests that eight weeks of probiotic supplementation may reduce overall psychological symptoms in cancer patients undergoing chemotherapy. Larger trials with rigorous controls and longer interventions are needed to confirm these preliminary findings.