The Juice Products Assn. emphasizes the value of the vitamins, minerals and phytonutrients in juice, especially when so many Americans eat so little fresh produce.
But scientists are increasingly questioning whether the benefits outweigh the sugar and calories that come with them. "The upside of juice consumption is so infinitesimal compared to the downside that we shouldn't even be having this discussion," said Dr. Robert Lustig, a pediatric endocrinologist at UC San Francisco.
Researchers haven't published head-to-head comparisons of how juice and soda contribute to weight gain, but there is evidence that high juice consumption increases the risk of becoming overweight or obese, especially among kids.
One of the earliest studies, in 1997, examined 168 preschool-age children in upstate New York. Kids who drank at least 12 ounces of juice a day were 3 1/2 times more likely than other kids to exceed the 90th percentile for body mass index, qualifying them as overweight or obese.
A 2006 study of 971 low-income youngsters found that each extra glass of juice a day caused children who were already overweight or obese to gain an extra pound each year.
The link between juice and weight gain isn't always found, however. In a 2008 review of 21 studies, six supported the connection and 15 did not.
In fact, several researchers have linked juice to healthier diets and lower weights. A 2008 report of 3,618 children ages 2 to 11 found that kids who drank at least 6 ounces of juice a day consumed less fat and more vitamins and minerals than kids who drank no juice at all.
But many experts say the data simply reflect a correlation between juice and healthful diets, not a causal relationship.
"Kids who drink more juice are more likely to be eating breakfast, and kids who eat breakfast tend to weigh less than kids who don't," said Kelly Brownell, director of the Rudd Center for Food Policy and Obesity at Yale University.
There's also concern that children who drink lots of sweet beverages such as juice will develop a lifelong preference for sweeter foods. A 2004 Dutch study found that 8- to 10-year-olds preferred sweeter drinks after consuming a sugary orangeade for eight days. They also drank more of it as they acclimated to its sweet taste.
Doctors and health officials have been persuaded to de-emphasize juice in recent years.
The American Academy of Pediatrics' nutrition committee revised its policy in 2001 to recommend that children ages 1 to 6 drink no more than one 4- to 6-ounce serving of juice a day and older kids have no more than two.
"Because juice is viewed as nutritious, limits on consumption are not usually set by parents," the committee wrote in “The Use and Misuse of Fruit Juice in Pediatrics.”;107/5/1210 "Like soda, it can contribute to energy imbalance," causing the weight gain that leads to obesity.
The government's 2005 dietary guidelines recognize that juices can be good sources of potassium, but recommend whole fruit for the majority of daily fruit servings to ensure adequate intake of fiber.
In October, the federal Special Supplemental Nutrition Program for Women, Infants and Children introduced vouchers for fresh produce and reduced the juice allowance. That's a change Billington and his colleagues in the Minnesota Medical Assn. had been pushing for since 2006.
"Having apple juice and eating an apple are not the same," he said.