Juice is a delicious source of carbohydrates and vitamins, and can be part of a healthy diet, but a new report from the American Academy of Pediatrics clarifies infants (under one year old) should not drink fruit juice, and children of all ages should be consuming a lot less of the sweet stuff.

In a new policy statement from the Committee on Nutrition of the American Academy of Pediatrics details how little juice children of different ages should drink and why.

Infants under 1 year old can eat fruit, but shouldn’t have juice. If a doctor recommends it for constipation or other reasons, the child should drink it from a cup and not a bottle or sippy cup.

Toddlers ages 1 to 6 can have 4 fluid ounces of juice per day at most, but should get the rest of their fruit intake from actual fruit. They should not take juice to bed or carry it around with them.

Children ages 5 to 18 can have up to 8 ounces of juice per day, but should also be eating fruit more than drinking fruit juices. (That goes for adults over 18, too.)

One problem is that the “juice” products sold at the supermarket usually contain between 10% and 99% juice, with added vitamins. Even when kids are served 100% juice, what pediatricians are concerned about is what isn’t in a glass of juice. That includes the fiber and protein that a child would get from eating a whole piece of fruit.

When toddlers (ages 1 to 4) drink too much juice from certain fruits, they aren’t able to absorb all of the carbohydrates, and that can lead to diarrhea. Caregivers may employ this fact on purpose when toddlers are constipated, and pediatricians recommend it, but it’s also something to keep in mind when serving juices like prune, pear, or apple to kids.

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