Study: A Daily Glass Of Fruit Juice May Help Improve Diet, Mood

Counting Juice Toward Daily Fruit Goals Worked Just as Well as Eating Whole Produce, Study Says

A glass of orange juice at breakfast has long been caught in a tug-of-war between nutrition scientists. Is it a legitimate serving of fruit, or just sugary water with a health halo? A new study out of Newcastle University suggests that, when paired with nutrition guidance and grocery support, allowing one daily serving of fruit juice or a smoothie to count toward produce goals may help adults eat more fruit overall, and may improve their mood in the process.

Published in the British Journal of Nutrition, the research focused on adults already falling short of the UK’s “5-a-day” recommendation, which calls for five servings of fruits and vegetables daily. Only around 17% of UK adults meet that goal. Researchers tested whether allowing one daily serving of juice or a smoothie to count toward the target would help people get there, and whether it would cause any harm.

In this small, four-week trial, it helped people raise their produce intake, and researchers did not detect short-term harm in the health markers they measured.

Study Targeted Adults Eating Fewer Than 2 Servings of Produce a Day

Researchers recruited 42 healthy adults, 21 men and 21 women between the ages of 18 and 65, from the staff and student population at Newcastle University. All participants were eating two or fewer servings of fruits and vegetables per day at the start. Roughly half in each group had a body mass index in the overweight or obese range.

Participants were randomly divided into three groups. The control group was asked to keep eating as usual. A second group was told to increase produce intake to meet the 5-a-day target using only whole fruits and vegetables. A third group had the same goal but could count a 150-milliliter portion of 100% fruit juice or a smoothie, just over half a cup, as one of their five daily servings.

To remove cost as a barrier, all participants received weekly grocery vouchers. Both groups working to eat more produce also received a 16-page educational booklet addressing common obstacles, including cost, preparation time, and unfamiliarity with certain foods.

Participants tracked their diet using an online tool called Intake24, provided blood samples at the start and end of the trial, and completed standard questionnaires measuring depression and anxiety symptoms.

Fruit Juice Helped People Hit Their 5-a-Day Fruit and Vegetable Target

Both groups with financial support and the booklet increased their intake dramatically compared to the control group, which stayed near its baseline of about 2.5 daily servings.

By the end of four weeks, the whole-produce group was averaging about 8.9 servings per day. The juice-included group averaged about 6.6. The gap between them was close enough that researchers could not say one approach worked better than the other for total produce consumption.

Worth noting: the gains came mostly from eating more fruit, not vegetables. Vegetable intake did not increase in either intervention group compared to controls, which matters because vegetables carry their own health benefits and are typically harder to add to a daily routine.

Fruit Juice Drinkers Showed Lower Depression Scores in Produce Study

Mental health was where things got interesting. People in the juice and smoothies group scored notably lower on a standard depression symptom questionnaire than the control group by the end of the study. People in the whole-produce group also had lower depression scores than controls, but that gap was not large enough to rule out chance. Anxiety scores did not meaningfully differ between any of the groups.

Neither intervention produced meaningful changes in the blood-based health markers tested, including measures of blood fats, inflammation, and blood sugar. The juice group did consume more free sugars, a regulatory term for sugars no longer contained within a fruit’s cell structure, putting them in the same official category as sugars added to sodas, but this did not translate into detectable metabolic changes over four weeks. Digestive symptoms did not meaningfully differ between groups either.

One notable pattern was that juice group participants drank about twice the recommended daily portion on average, suggesting people tend to pour more than the official 150-milliliter serving even when shown exactly what that amount looks like.

The Fruit Juice Debate Is Far From Settled

Whether fruit juice belongs in healthy eating guidelines is genuinely contested worldwide. France no longer counts juice toward recommended fruit intake. New Zealand classifies it alongside sugary drinks. Germany recommends consuming it only occasionally. The United States and United Kingdom take more permissive stances, with the UK allowing one daily 150-milliliter portion to count toward the 5-a-day target.

At the center of the debate is sugar. When fruit is juiced, its sugars fall into the same regulatory category as sugars added to sodas. Critics argue this makes juice more like a soft drink than a health food. A growing body of research cited by the study’s authors suggests the picture is more complicated than that comparison allows.

For adults eating far too little produce, adding juice or smoothies alongside education and financial support may be a practical way to close the gap. At least over four weeks, it did not come at a measurable cost to physical health. Longer, larger trials are needed to know whether those effects hold.

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Disclaimer: This article is based on a single small-scale, four-week study conducted at one university. The findings are preliminary and should not be taken as a recommendation to change your diet. Consult a qualified healthcare or nutrition professional before making dietary changes.

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