Cold-pressed juices are a waste of money. The (lack of) science behind them says so.

Dear Julia: Are there any health benefits from drinking cold-pressed juices? I'm also wondering if it’s actually healthier than just eating normal fruits and veggies.

Every day, I walk by a cold-pressed juice shop. It serves $12 bottles like the ones you describe out of backlit refrigerators that look like they belong in outer space. I'm always tempted to buy one, but have also wondered whether this "healthy convenience in a bottle" is really all that special.

First, let's clear up why cold-pressing advocates say these juices are better. If you've ever made fresh juice at home, you've probably used a centrifugal blender of some kind, squeezing the produce through fast-spinning blades, shredding out the juice, removing pulp, and generating some heat in the process.

Kate Upton juicing. (Alo Ceballos/FilmMagic)

According to the cold-press fans, that gentle heating degrades the juice's flavor and nutritional value. So their alternative method is to apply thousands of pounds of pressure to crush out the juice instead. These drinks are marketed as being extra raw, fresh, and nutritionally superior. Some companies even go so far as to suggest that their products remove toxins (a bunk concept; see here), stave off cancer, and help with weight loss. The claims are appealing enough to have helped spawn a trend, attracting celebrity endorsements and giving rise to cold-pressed juice stands in yoga studios, markets, and even Starbucks stores across the country.

But the truth is there's no sound evidence to support all these claims of superiority. I couldn't find any scientific literature comparing the nutritional value and absorption of cold-pressed versus regular juices, and the researchers I contacted said they weren't surprised.

"You didn't find much because there's almost no evidence out there," said Lydia Bazzano, a professor in nutrition research at Tulane University School of Public Health and Tropical Medicine.

Bazzano noted that the temperatures in regular juice blenders don't get high enough to significantly alter the plants' chemicals and vitamins. And even if temperature differences did change the nutritional value of the juice, they wouldn't be dramatic enough to then affect a person's health.

So what about drinking fresh juices in general versus eating fruits and vegetables? Juicing advocates claim that the juice hits your system in a more beneficial way because you don't need to digest all that pesky fiber found in whole produce.

Bazzano explained that the only way juices hit your system faster is in a rapid sugar load akin to drinking a soft drink. "The actual fruits have fiber, which is indigestible, and slows the glucose and fructose absorption in you body," she said. "It's better to eat your fruits and veggies than juice them."

Jeffrey Blumberg, a nutrition researcher at Tufts University, was a little more generous. "It is possible that the juicing process releases some vitamins and phytochemicals that are bound to fiber or other cellular components," he wrote in an email, explaining that this could allow those vitamins and nutrients to be absorbed into a person's system more easily. But he also noted that he's never seen evidence behind this idea, and that he'd want some before believing it.

All the hype around fresh juice usually overlooks any discussion about calories. Marion Nestle, a New York University professor and author of the new book Soda Politics, flagged her concern that even the freshest juices can deliver a quick hit of calories and sugar without any accompanying satiety.

"It’s one thing to eat an apple. It’s quite another to drink the juice of three apples, which is easy to do with apple juice," she warned. "Juices, like any other source of liquid sugars, are best consumed in small amounts."

In her mind, the only time drinking juice is better than eating fruits and vegetables is when people don’t have teeth.

Welcome to Dear Julia, a weekly column where readers can submit everyday health questions. Which over-the-counter painkillers work best? Is it better to run or walk for exercise? How much harm does frequent flying do to your body? Julia Belluz will sift through the research and consult with experts in the field to figure out how science can help us live happier and healthier lives.

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