Babies under a year old should not be drinking juice at all, while older kids should drink very little of it, the American Academy of Pediatrics says in a new guidance statement.

According to the new advice released on Monday, children younger than 12 months of age should not drink juice unless a doctor recommends it to manage constipation.

Toddlers and preschoolers up to three years of age should not have more than four ounces, or 125 millilitres of juice per day.

Kids aged four to six years of age should have no more than four to six ounces, while older kids should have no more than 8 ounces or 250 ml a day.

The doctors’ group has long advised against offering juice to babies younger than six months of age, but in this first update of its juice-drinking recommendations since 2001, they now advise the age limit be raised to 12 months of age.

Fresh fruit is always preferable to juice, which “may contribute to excessive weight gain,” the group notes, adding whole fruit provides dietary fibre and has less sugar and calories than juice.

“Parents may perceive fruit juice as healthy, but it is not a good substitute for fresh fruit and just packs in more sugar and calories,” said Dr. Melvin B. Heyman, the co-author of the statement.

“Small amounts in moderation are fine for older kids, but are absolutely unnecessary for children under one.”

The authors of the guidance paper say fruit juice might be marketed as a healthy, natural source of vitamins and children prefer it because juice tastes good. But they say juice also has a high sugar content that contributes to increased calorie consumption and tooth decay.

The new guidance paper also notes that children of all ages should not consume unpasteurized juice products.

And it warns that grapefruit juice can interfere with the effectiveness of certain medications.

The full statement appears in the journal, Pediatrics.