Back away from the juice, lest you get clocked in the head by some chemically induced misery.

Dramatic, sure, but new findings from Zui Narita and his colleagues at the National Center of Neurology and Psychiatry indicate drinking juice could make it harder to prevent depression.

“Vegetables and fruits are thought to be useful for driving away depressive symptoms, but it turned out that replacing them with juice may just prove counterproductive,” said Narita, who is the chief of the Mental Function Research Section at the center’s National Institute of Mental Health. 

One reason for the study was a limited knowledge of how certain beverages can impact depression among Asians.

“We likewise found that coffee can have totally opposite effects depending on whether it is consumed with sugar or drunk black,” he added.

Sugar is the likely culprit in the expansive study where 94,873 people across seven prefectures were surveyed on their lifestyle habits in 2011.

A questionnaire on depression was sent out to participants five years later in 2016 and 80,497 responded, with 18,172 displaying depressive symptoms.

Subjects were between the ages 40 and 70 and resided in Akita, Iwate, Ibaraki, Nagano, Kochi, Ehime and Nagasaki at the time.

The pool purposefully excluded those already diagnosed with depression as well as those with physical health conditions reported to be associated with it.

Specifically, individuals who suffered from a stroke, heart attack, diabetes or cancer were not polled.

Based on their answers, the researchers estimated how much of certain beverages each participant consumed. These comprised carbonated drinks, vegetable and fruit juice, 100-percent fruit juice, sweetened and black coffee, with green tea rounding out the list.

Subjects were then divided into four categories by drink: zero consumption; those who drink a small amount; those who drink a medium amount; and those who consume a large amount. 

The results showed participants who favor carbonated beverages, fruit and vegetable juice, sweetened coffee and even 100-percent fruit juice had a greater chance of developing depression.

Researchers discovered this by calculating the "risk difference" in points between the group with the highest consumption and the group who abstained entirely.

To get into the nitty-gritty of the data, people who drink large amounts of sweetened beverages in general were 3.6 points more susceptible to depression. People who consume large amounts of carbonated drinks were just behind at 3.5 points.

Participants who chug vegetable and fruit juice also barely placed below 100-percent juice lovers at 2.3 points versus 2.4 points. Those who take their coffee with sugar were in the middle with 2.6 points. 

“Juice squeezed from veggies and fruits using juicers and other appliances can hardly have a negative influence on one’s health,” said Narita. “It should be noted sugar could be added to adjust the sweetness of 100-percent juice drinks easily found in stores, even if they are reconstituted from concentrate.”

This is the process of adding water back to fruit previously drained to create the concentrate.

Sipping on sugary drinks can lead to a decreased volume of proteins necessary for nerve cells’ activity, according to the research team’s accounts. Sugar has inflammatory effects, too.

On the other hand, subjects who prefer black coffee, and a lot of it, were 1.7 points less likely to develop depressive symptoms than those who didn’t drink it at all.

This is attributed to caffeine containing antioxidants and having anti-inflammatory effects, although, adding sugar can negate these benefits.

No statistically significant difference was reported about green tea.

“Overall, refraining from sweet drinks characterized by high amounts of sugar appears to be helpful in protecting people from depression,” Narita said. “One should understand that juice products are totally different from genuine veggies or fruits.”

A helpful reminder as Japan’s seasonal fruit concoctions are a familiar temptation.

The team was also thorough in eliminating other factors that could influence depression that included location, age, gender, body mass index (BMI), smoking habits, frequency of alcohol consumption and time spent walking.

Their findings were published in the specialized journal Clinical Nutrition at: https://doi.org/10.1016/j.clnu.2024.04.017