Fruit juice lives in a confusing place in nutrition advice. Some people see 100% juice as a simple way to get more fruit. Others see it as little more than sugar in a glass.
A new study from Newcastle University adds a little nuance to that debate, but not a final answer. In a small randomized controlled trial, adults with low fruit and vegetable intake were given support to eat more produce. One group also included a daily glass of 100% fruit juice or a smoothie. After four weeks, that group reported lower depression scores compared with the control group.
The study, published in the British Journal of Nutrition, was funded by the Fruit Juice Science Centre, which says it is supported by donations from orange producers, juice manufacturers and packaging companies in Europe and Brazil. That funding does not invalidate the findings, but it does make context especially important.
The trial included 42 adults who were eating two or fewer portions of fruits and vegetables per day at the start of the study. Participants were divided into three groups of 14. One group was asked to maintain its usual diet. A second group received support to increase fruit and vegetable intake using whole fruits and vegetables only. A third group received similar support but was also asked to include one daily glass of 100% fruit juice or a smoothie.
All participants received £10 per week, which is equivalent to about $10-$15 per week. The two groups working toward the UK’s “5-a-day” target, which encourages people to eat at least five portions of fruits and vegetables daily, also received educational materials intended to help them overcome common barriers to eating more fruits and vegetables.
“While most people know eating 5-a-day can be good for your health, many people struggle to,” said Courtney Neal, who completed the study while at Newcastle University and is now at the University of Liverpool.
In U.S. terms, that roughly aligns with familiar advice to fill more of the plate with fruits and vegetables, though American guidance is usually described in cups rather than “portions.”
The researchers measured mood using validated questionnaires for anxiety and depression. After four weeks, the juice and smoothie group had lower depression scores than the control group. The difference was 2.52 points on a 27-point scale, with an adjusted mean score of 5.45 in the control group and 2.93 in the group that included juice or smoothies.
That finding is interesting, but it should be read carefully. The study does not show that fruit juice treats depression or that adding juice alone improves mental health. It was small, short and focused on adults with low fruit and vegetable intake who were also receiving support to improve their overall diet.
The study also does not clearly show that juice or smoothies were better than whole fruits and vegetables. The findings reported the lower depression scores in the juice and smoothie group compared with the control group, not as a proven advantage over the whole-produce group.
The more useful takeaway may be that a small serving of 100% juice or a smoothie did not appear to prevent people from improving the rest of their diet. According to dietary recalls completed during the study, both intervention groups increased their fiber intake by an estimated 8 to 10 grams per day. That suggests the juice and smoothie group was still adding fiber-rich foods, rather than simply replacing whole produce with a drink.
That matters because one common concern about juice is what it leaves out. Whole fruits contain fiber and usually take longer to eat, which can help with fullness and blood sugar response. Juice contains vitamins and plant compounds from fruit, but it is easier to consume quickly and usually contains little to no fiber unless it is part of a smoothie or blended product.
The study also found no adverse effects on metabolic health markers over the four-week period among participants consuming juice or smoothies as part of the intervention. But the short timeline and small sample mean the findings should not be used to draw broad conclusions about long-term blood sugar, weight or metabolic health.
“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,” said Oliver Shannon, lecturer in nutrition and ageing at Newcastle University and one of the senior authors of the study. “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.”
That “part of the solution” framing is probably the safest way to understand the findings. For people who struggle to eat enough fruits and vegetables, a small glass of 100% juice or a smoothie may be one practical tool, especially when used alongside whole fruits and vegetables. It is not the same as drinking soda, but it is also not a substitute for an overall healthy diet.
Shannon said the mood finding deserves more study.
“The finding that fruit juice drinkers had reduced depression scores is promising and worthy of further exploration, particularly in individuals experiencing poor mental wellbeing,” he said. “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 wellbeing.”
For now, the study is best understood as a small, early piece of a larger conversation. It suggests that 100% fruit juice or smoothies may be able to fit into a broader strategy for increasing fruit and vegetable intake. But it does not prove that juice improves mental health, and it should not be read as a reason to prioritize juice over whole fruit.