The American Academy of Pediatrics recommends that children should not drink fruit juices in their first year of life (1). Fruit juices contain hardly any fiber and above all too much sugar. In Germany, fruit juice labeled with “100 % fruit content” is not allowed to contain any additional sugar, but the fruit juice itself already contains the natural fruit sugar fructose. The carbohydrate content in juices (11-16 %) is about twice as high as in breast milk.
If breast milk or baby food are proportionally replaced by juice, it may result in low intakes of protein, fats and micronutrients such as iron, calcium and zinc. Infants who get used to an excessive consumption of fruit juices are therefore at high risk of malnutrition. In addition, fruit juices (such as grapefruit) affect the absorption of medicines from the intestine and their breakdown in the liver and can promote chronic diarrhea. Natural juices may contain additional pathogens such as Salmonella. The American pediatricians therefore advise to abstain from fruit juices under the age of one, as these offer no nutritional benefit. Adequate portions of fresh fruits are the better option.
The Commission of Nutrition of the German Society for Pediatrics and Adolescent Medicine recommends exclusive breastfeeding in the first 4 to 6 months of life and the gradual introduction of complementary food between the 4th and 7th month. Vitamin C-containing fruit juices can be added to the vegetable-potato-meat-pulp to increase the iron absorption. An additional intake of fluid is only required if the child consumes three solid meals a day (at about 7 months) and the total water content of the food taken is therefore reduced, except for unusual fluid loss such as fever or diarrhea. The child should drink from a mug or a cup (but not a bottle) and prefer calorie-free beverages such as water or unsweetened teas (2).
 Recommendations: For 1 to 3 year old infants the intake of juice should be limited to a maximum of 4 ounces/day (113 g), 4 to 6 ounces/day (170 g) for children 4 through 6 years and not more than 8 ounces per day for children 7 to 18 years of Age
(1) MB Hyman et al. Fruit Juice in Infants, Children, and Adolescents: Current Recommendations. Pediatrics . Published Online (date) May 22, 2017. Doi: 10.1542/peds.2017-09, available via: http://pediatrics.aappublications.org/content/early/2017/05/18/peds.2017-0967
(2) C. Bührer et al. (2014). (German) Ernährung gesunder Säuglinge Empfehlungen der Ernährungskommission der Deutschen Gesellschaft für Kinder- und Jugendmedizin. Monatsschrift Kinderheilkunde, 6, 527-538.available via: https://www.dgkj.de/uploads/media/1406_EK_Empfehlungen_Erna%CC%88hrunggesunder_Sa%CC%88uglinge.pdf (English summary available via: https://link.springer.com/article/10.1007/s00112-014-3129-2)