Daily fruit juice linked to lower depression scores in Newcastle trial
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- Newcastle University researchers reported in a four-week randomized controlled trial that the group adding one daily glass of 100% fruit juice or a smoothie to their diet scored 2.52 points lower on the 27-point PHQ-9 depression scale than controls (adjusted means of 5.45 vs. 2.93), a difference the team called modest but statistically significant.
- Dr. Courtney Neal, who led the study while at Newcastle and is now at the University of Liverpool, framed the result as evidence that "simple, cost-effective solutions, like drinking a small glass of 100% fruit juice or a smoothie daily, could help people reach their 5-a-day, with potential benefits for mental well-being."
- The trial, published in the British Journal of Nutrition and funded by the Fruit Juice Science Centre, split 42 adults eating two or fewer portions of fruit and veg per day into three groups of 14 — control, whole-foods-only, and whole-foods plus juice — with all groups receiving £10 a week and intervention groups also getting educational materials.
- Both intervention groups increased their daily fiber intake by an estimated 8–10 grams, suggesting that adding juice did not displace whole fruits and vegetables from the diet.
- Researchers found no adverse effects on metabolic health markers after four weeks among juice consumers despite concerns about the sugar content of fruit juice.
- Dr. Oliver Shannon, senior author and Lecturer in Nutrition and Ageing at Newcastle, said the depression finding backs prior studies reporting improved brain blood flow and cognitive function after citrus juice consumption and is "worthy of further exploration, particularly in individuals experiencing poor mental well-being."
- The context: fewer than 1 in 5 (17%) UK adults and only 1 in 10 teenagers currently meet the 5-a-day recommendation, with the cost of fresh produce cited by the authors as a key barrier.
Why it matters: The 42-person, four-week Newcastle trial offers preliminary evidence that adding a daily glass of fruit juice to a healthier diet modestly lowers depression scores, but the researchers themselves called the 2.52-point PHQ-9 gap "modest" and urged larger, longer studies — and the work was funded by the Fruit Juice Science Centre, an industry-backed body whose involvement is worth weighing against the headline-friendly finding.
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