Daily Fruit Juice Linked to Lower Depression Scores

Four-Week Trial Reports Mood Improvement

Researchers at Newcastle University in the UK found that adults who added a daily glass of 100% fruit juice or a smoothie while increasing their fruit and vegetable intake recorded lower depression scores after four weeks.

The randomized controlled trial involved 42 adults who initially consumed two or fewer portions of fruit and vegetables each day. Researchers divided them into three groups to examine whether different approaches to reaching the UK's five-a-day target affected dietary intake, mood and health markers.

The group combining whole fruits and vegetables with a daily glass of juice or smoothie recorded depression scores 2.52 points lower than the control group on the 27-point Patient Health Questionnaire-9 scale.

The researchers described the difference as modest but statistically significant. The study did not find a statistically significant difference in anxiety scores between the groups.

Participants Increased Fruit and Vegetable Intake

Fourteen participants served as controls and were asked to maintain their usual diets. Another 14 received financial and educational support to increase their consumption to five portions a day using whole fruits and vegetables.

The remaining 14 participants received similar support but also consumed one glass of fruit juice or a smoothie daily. All participants received £10 a week during the trial, while the two intervention groups received additional educational materials.

Both intervention groups increased their fruit and vegetable consumption. Dietary records also indicated that participants in both groups increased their daily fiber intake by an estimated 8 to 10 grams.

Researchers said the findings suggested that adding juice did not prevent participants from consuming other fiber-rich fruits and vegetables.

"Simple, cost-effective solutions" could help people reach five-a-day targets and potentially support mental well-being, said Courtney Neal, who completed the research at Newcastle University and is now at the University of Liverpool.

Researchers Call for Further Study

The study measured mood using validated questionnaires, including the PHQ-9 for depression symptoms and the GAD-7 for generalized anxiety symptoms.

Among the participants consuming juice or smoothies, the adjusted mean depression score was 2.93, compared with 5.45 in the control group. Researchers reported the difference as statistically significant after four weeks.

The study also examined metabolic health markers because fruit juice contains naturally occurring sugars. Researchers reported no adverse effects on the measured metabolic markers during the four-week intervention.

Oliver Shannon, a lecturer in nutrition and ageing at Newcastle University and a senior author of the study, said the results were promising and deserved further investigation, particularly among people experiencing poor mental well-being.

"The finding that fruit juice drinkers had reduced depression scores is promising and worthy of further exploration," Shannon said.

The study was published in the British Journal of Nutrition and was funded by the Fruit Juice Science Centre.

Evidence Does Not Establish a Treatment

The findings add to research examining possible links between fruit consumption, diet and mental well-being, but the trial has important limitations. Only 42 people participated, and researchers followed them for just four weeks.

The design also makes it difficult to determine whether juice itself caused the lower depression scores. Participants in the juice group simultaneously increased their overall fruit and vegetable intake and received financial and educational support.

The study therefore does not establish that drinking fruit juice prevents or treats depression. It also does not demonstrate that juice provides greater mental-health benefits than eating additional whole fruit.

A Dietary Lead for Future Research

The researchers said the findings could be relevant in efforts to help people overcome practical barriers to meeting dietary recommendations. In the UK, only 17% of adults and about 10% of teenagers reportedly meet the five-a-day recommendation.

Neal said targeted support helped participants with initially low fruit and vegetable consumption make meaningful dietary changes. She said a small serving of 100% fruit juice or a smoothie could offer a practical way to increase fruit intake.

For now, the evidence points to a possible relationship between improved dietary habits and mental well-being rather than a proven effect of fruit juice itself. Larger, longer-term studies will be needed to determine whether the reduction in depression scores can be replicated and whether juice independently contributes to the effect.