Adding a daily glass of 100% fruit juice or a smoothie to a 5-a-day diet helped adults increase fruit and vegetable intake and was associated with lower depression scores after four weeks, with no adverse health effects observed. Credit: Shutterstock

Researchers found that a simple addition to a 5-a-day diet was associated with improved mental well-being in adults with low fruit and vegetable intake.

New research from Newcastle University suggests that drinking a daily glass of 100% fruit juice or a smoothie as part of the country’s 5-a-day nutrition recommendation may help improve mental well-being.

In a randomized controlled trial, adults who typically ate very few fruits and vegetables received support to increase their intake to the recommended five daily portions. Some participants followed the plan using only whole fruits and vegetables, while others included a daily serving of fruit juice or a smoothie.

After four weeks, both groups successfully increased their fruit and vegetable consumption. However, participants who added fruit juice reported lower depression scores than those who did not.

The findings, published in the peer-reviewed British Journal of Nutrition and funded by the Fruit Juice Science Centre, add to a growing body of evidence suggesting that practical dietary changes may benefit mental health.

Simple Dietary Changes Help People Reach 5-a-Day

Dr. Courtney Neal, who conducted the research at Newcastle University and now works at the University of Liverpool, said, “While most people know eating 5-a-day can be good for your health, many people struggle to.

“Our trial showed that when people with low fruit and vegetable intake were provided with targeted financial and educational support to address common barriers to eating 5-a-day, they were able to make meaningful changes to their diet. We found 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 wellbeing.”

Consuming the recommended amount of fruits and vegetables has been linked to a lower risk of chronic disease and better long-term health. Even so, only about 17% of adults in the UK and 10% of teenagers currently meet the 5-a-day recommendation.

Trial Results Show Lower Depression Scores

The four-week study involved participants who were eating two or fewer portions of fruits and vegetables per day at the start of the trial. All received support to reach five daily portions. One group ate only whole fruits and vegetables, while the other combined whole produce with one daily glass of fruit juice or a smoothie.

Researchers assessed mood using validated questionnaires that measured anxiety and depression. Participants who consumed fruit juice and smoothies alongside whole fruits and vegetables scored lower on measures of depression than the control group. Their scores were 2.52 points lower on a 27-point scale, a modest but statistically significant difference.

Dietary records indicated that both groups increased their fiber intake by an estimated 8 to 10 grams per day (0.28 to 0.35 ounces per day). This suggests that adding fruit juice did not discourage participants from eating other fiber-rich fruits and vegetables.

No Negative Health Effects Observed

The study included 42 participants and found no negative effects on metabolic health markers among those who consumed fruit juice and smoothies during the four-week intervention, despite ongoing concerns about sugar intake.

Dr. Oliver Shannon, Lecturer in Nutrition and Ageing at Newcastle University and one of the senior authors of the study, said: “Given the ongoing cost of living pressures in the UK, the price of fresh produce is often a barrier for people trying to eat more fruit and vegetables. Our study shows that drinking a daily glass of fruit juice or a smoothie could be part of the solution and help people reach 5-a-day fruit and vegetable targets.

“The finding that fruit juice drinkers had reduced depression scores is promising and worthy of further exploration, particularly in individuals experiencing poor mental well-being. It backs up studies which report improved brain blood flow and cognitive function after people drink citrus juices. Simple dietary changes—like increasing fruit intake, including through a daily glass of juice—could play a role in supporting mental well-being.”

Reference: “Including fruit juice and smoothies within 5-a-day fruit and vegetable intake recommendations: A randomised controlled trial investigating impact on levels of intake, mood, and markers of health” by Courtney Neal, Georg Lietz, Kirsten Brandt, Anthony W Watson and Oliver M Shannon, 22 May 2026, British Journal of Nutrition.
DOI: 10.1017/S0007114526107569

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