Can a Daily Glass of Fruit Juice Boost Your Mood?

A four-week trial found lower depression scores in adults adding 100% fruit juice or smoothies to a diet richer in fruits and vegetables. But does juice boost mood, too?

Could something as simple as adding a glass of fruit juice to your diet have an effect on your mood? A new randomized controlled trial suggests it might, but the finding needs to be understood carefully (1^✔ ✔Trusted Source
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

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Researchers from Newcastle University, UK, found that adults with very low fruit and vegetable intake who were encouraged to increase their consumption and include a daily serving of 100% fruit juice or a smoothie had significantly lower depression scores after four weeks compared with a control group.

The study was published in the British Journal of Nutrition in 2026.

But there is an important distinction: the study found an improvement in depression symptoms measured by a questionnaire; it did not show that fruit juice can prevent or cure clinical depression.

What Exactly did The Fruit Juice Study Find?

The researchers recruited 42 healthy adults aged 18 to 65 who were eating two or fewer servings of fruits and vegetables per day.

Participants were randomly assigned to three groups:

Both intervention groups successfully increased their fruit and vegetable consumption.

However, the fruit juice/smoothie group had significantly lower depression scores than the control group at the end of the study.

Their average PHQ-9 depression score was 2.93, compared with 5.45 in the control group, a difference of 2.52 points on the 27-point scale. The whole-fruit-and-vegetable group also had a lower average score than controls, but the difference narrowly did not reach statistical significance.

Does this Mean Fruit Juice Treats Depression?

No. This is probably the most important message for readers.

The study measured symptoms using the Patient Health Questionnaire-9 (PHQ-9). A lower score indicates fewer reported depressive symptoms, but this is not the same as diagnosing or treating major depressive disorder.

The researchers themselves describe the finding as promising and say it needs further investigation, particularly in people experiencing poor mental well-being.

There was also no significant improvement in anxiety scores between the groups.

So, the evidence supports a more cautious statement: Adding 100% fruit juice or a smoothie as part of a healthier, fruit-and-vegetable-rich diet was associated with lower depression symptoms over four weeks.

It does not support the headline claim that “one glass of juice cures depression.”

Why Might Fruits and Juice Affect Mood?

Scientists are increasingly studying the connection between diet, the gut and the brain. Fruits and vegetables provide vitamin C, carotenoids, flavonoids, folate and other plant compounds. Some of these compounds have antioxidant and anti-inflammatory properties.

The Newcastle researchers also discuss possible involvement of the gut-brain axis, including changes in the gut microbiome and production of compounds such as short-chain fatty acids. Flavonoids may also influence biological pathways involved in brain function.

However, these are possible mechanisms, not mechanisms proven by this particular four-week trial.

That distinction matters.

What About the Sugar in Fruit Juice?

Fruit juice has often been debated because it contains naturally occurring sugars and generally has less fibre than whole fruit.

Interestingly, the Newcastle trial did not find adverse changes in the metabolic health markers measured over the four weeks in the juice/smoothie group. Participants also increased their estimated fibre intake by about 8–10 grams per day, suggesting that adding juice did not replace all the fibre-rich whole fruits and vegetables in their diets.

That does not mean unlimited juice is healthy.

The study specifically examined 100% fruit juice or smoothies as part of an overall effort to increase fruit and vegetable intake. It should not be interpreted as evidence that sugary fruit drinks, fruit-flavoured beverages or large quantities of juice provide the same benefit.

So, Should You Drink Fruit Juice Every Day?

For someone who rarely eats fruits and vegetables, a small serving of 100% fruit juice may be one practical way to increase fruit intake—but whole fruit should not automatically be replaced with juice.

The study is particularly interesting because many people struggle to reach recommended fruit and vegetable targets. The researchers suggest that juice or smoothies could provide a convenient option for people who find fresh produce difficult to buy or consume regularly.

A practical approach is to make whole fruits and vegetables the foundation of the diet, while treating 100% juice as one possible addition rather than a mental-health remedy.

How Strong Is the Evidence?

The results are interesting, but this was a small, short-term trial.

Only 42 healthy adults participated, and the intervention lasted four weeks. Participants were also university staff or students in the UK, which means the findings may not automatically apply to children, older adults, people with diabetes or other chronic illnesses, or people diagnosed with depression.

The study was also open-label, meaning participants knew which dietary intervention they were receiving.

Most importantly, the research was funded by the Fruit Juice Science Centre, an organisation funded by donations from orange producers, juice manufacturers and packaging companies.

That funding does not invalidate the results, but it is an important piece of information when interpreting research about a commercially relevant food product.

The Bottom Line

A small randomized trial has raised an interesting possibility: improving fruit and vegetable intake, with 100% fruit juice or a smoothie included, may be associated with fewer depressive symptoms.

But the study does not show that fruit juice treats depression. Only 42 healthy adults took part, the intervention lasted just four weeks, and participants were not being treated for clinical depression.

The findings are better viewed as an early clue about the potential connection between diet and mental well-being, rather than a reason to start drinking juice as a mood treatment.

For now, the practical message is simple: build a diet rich in fruits and vegetables, and don’t mistake a promising nutrition finding for a proven treatment for depression. If persistent sadness, loss of interest, hopelessness or other symptoms of depression are affecting daily life, professional assessment and evidence-based treatment remain important.

Reference:

1. 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 – (https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/including-fruit-juice-and-smoothies-within-5aday-fruit-and-vegetable-intake-recommendations-a-randomised-controlled-trial-investigating-impact-on-levels-of-intake-mood-and-markers-of-health/7B7C823BCA28C22B9C5D5C64719CB7A4)

Source-Medindia