Impact of fruit smoothie supplementation on psychological distress in patients undergoing opioid agonist therapy

Background
People with opioid use disorder often have unhealthy diet patterns with a low intake of fruits and vegetables, as reflected in their biochemical indicators. A diet low in fruits and vegetables is associated with an increased risk of several diseases and premature death. Studies centered on diets abundant in fruits and vegetables have indicated a decrease in psychological distress among diverse populations, however there is limited data available for individuals undergoing opioid agonist therapy. This trial evaluates the efficacy of fruit smoothie supplementation to people receiving opioid agonist therapy compared to standard treatment without supplementation.

Methods
This study is a multicenter individually randomized controlled trial with two parallel groups and an allocation ratio of 5:3 between the intervention and control arm. Three hundred and nineteen individuals were included in the study. The follow-up of the main outcomes of the trial was completed in November 2023. The control group received standard treatment and the intervention group additionally received a daily dose of 250 ml fruit smoothie containing apple, pineapple, mango, bananas, orange, berries, passion fruit, and lime for 16 weeks. The main outcome was the level of psychological distress measured by the ten-item version of the Hopkins Symptom Checklist (SCL-10) at baseline and at the end of the intervention. 

Results
At baseline, 184 (95%) in the intervention arm and 115 (93%) in the control arm had an intake of three or less servings of fruits and vegetables per day. In the intervention arm, the mean SCL-10 score at baseline was 2.31(SD 0.73) and was reduced to 2.24 (SD 0.72) at the end of the trial. In the control arm, the mean SCL-10 score was 2.33 at baseline (SD 0.74) and was reduced to 2.24 (SD 0.76) at the end of the trial period. The intention to treat analysis showed no significant difference in change of psychological distress between the intervention and control groups (0.03; -0.10;0.16).  

Conclusions
Our study showed that receiving fruit smoothies as a supplement had no significant effect in reducing psychological distress in people receiving opioid agonist therapy. Whether the intervention may have influenced the other outcomes within the 16-week timeframe is yet to be evaluated.