The marketing for freshly pressed and blended juices promises instant energy, weight loss, a flood of vitamins and minerals - all in a single, portable, gulpable serving.
But according to dietitians and nutrition scientists, juice is far from the healthiest way to consume fruit, and one expert went so far as to call its popularity a dangerous trend.
"The fruit juice industry has essentially taken the 'apple-a-day' mentality and used it to sell fruit juices as healthy," said Barry Popkin, a professor in the department of nutrition at the University of North Carolina at Chapel Hill's Gillings School of Public Health.
Popkin and other experts would rather see people eating whole fruit. Because most juicing methods remove the produce's fiber, drinking juice omits one of the key benefits of eating fruit, while delivering huge amounts of sugar and calories.
"Every one of the long-term studies of the health effects of fruit juices shows that you increase your risk of diabetes and weight gain" with regular juice consumption, Popkin said.
Smoothies do provide fiber, as the entire fruit often goes into the blender, skins and all, but they still contain a lot of calories. Choosing a vegetable-based juice or smoothie is one way to reduce the sugar content, health advocates say.
The issue is not so simple, others say.
Epidemiological studies on juice consumption show correlations, not cause and effect, said Elizabeth Ward, a registered dietitian on Jamba Juice's Healthy Living Council. Ward said she does not consider juices miraculous but, because of the vitamins and minerals, they are a good alternative to beverages that only have calories.
But Lara Field, a pediatric dietitian at the University of Chicago Medical Center and founder of a nutrition counseling practice called Forming Early Eating Decisions, or FEED, said the sugar in fruit juice far outweighs any possible benefit from the concentrated vitamins and minerals. "Eating too much fruit can make us gain weight, just like eating too much candy," Field said.
Plus, the fiber in fruit complements the vitamins and minerals, so juice drinkers miss out on the optimal health benefits, said Bethany Doerfler, clinical research dietitian in the division of gastroenterology at Northwestern Medicine.
Diets higher in fiber are associated with lower risk of cardiovascular disease and lower body weight, yet most American adults only achieve half the recommended daily fiber intake, 25 to 38 grams.
Eating fiber also contributes to a feeling of fullness, or satiety, that helps prevent people from overeating. In one study, published in the journal Appetite in 2009, people who ate apple slices before lunch felt more full and subsequently consumed 15 percent fewer calories than those who drank apple juice.
Chewing might affect satiety as well.
In the same study, a third group of participants ate applesauce containing fiber comparable to that in the apple slices. That group still consumed more calories at lunch than those who ate raw apples - though not as many as the juice drinkers.
Research suggests chewing helps signal the body that it's eaten enough calories for the moment, Field said.
Some nutrition experts acknowledge that drinking produce is better than consuming none at all.
"Considering the fact that more than 90 percent of Americans are not meeting their recommendations of daily fruit, 100 percent fruit juice is an easy and convenient way to meet these goals," Diane Welland, a registered dietitian for the Juice Products Association, wrote via email.
"Americans do not eat enough fruits and vegetables, so any step (toward eating more produce) is better than none," said Cornell University nutritionist Christina Stark.
But Stark cautioned eaters not to choose the same fruit in the same form over and over again, as the goal should be "variety in all aspects" of the consumption of vegetables and fruits, from texture to type.