Researchers at Newcastle University asked adults who ate few fruits and vegetables to try a simple change: drink one glass of 100 % fruit juice or a smoothie every day while they worked toward the UK’s 5‑a‑day goal.
What the Study Found
After four weeks, both groups ate more produce, but the group that added juice reported feeling less depressed. Their depression score was about 2.5 points lower on a 27‑point questionnaire, a small but real improvement.
Why It Matters
Eating enough fruit and veg is linked to lower risk of long‑term diseases, yet only about 1 in 5 adults in the UK meet the recommendation. This trial shows that a tiny daily habit – a glass of juice – can help people reach the target and may also lift mood.
More Than Just Juice
Both groups also increased their fiber intake by roughly 8–10 g per day, showing that drinking juice did not replace whole fruits and vegetables. No negative effects on blood sugar or other health markers were seen after the month‑long trial.
How the Experiment Was Set Up
Forty‑two participants who ate two or fewer portions of fruit and veg each day were randomly placed into three groups:
- Control group – kept their usual diet.
- Whole‑food group – received £10 weekly plus guidance to reach 5‑a‑day using only fresh produce.
- Juice group – got the same support plus a daily glass of juice or a smoothie.
All participants completed mood questionnaires for anxiety (GAD‑7) and depression (PHQ‑9) and recorded what they ate for four separate 24‑hour periods.
Takeaway
The findings suggest that a modest, affordable change—adding a glass of real fruit juice or a smoothie each day—can help people meet fruit‑and‑veg goals and may improve mental well‑being. More research is needed, but the result is promising for anyone looking for a simple mood‑boosting habit.