Energy requirements
The relative energy requirement, considered per kg of body weight, is maximum in the first month of life, where it reaches values three times higher than those of an adult.
After the first weeks of life the caloric demands tend to decrease; however, by increasing its body weight hand in hand, the newborn needs a higher energy intake in absolute terms. For this reason, if during the first six months the caloric coverage given by breast milk is sufficient, after this period the weaning can and must be started. The World Health Organization recommends not starting it before the fourth month of life and not after the sixth month. An early weaning could in fact lead to allergic problems, while a late weaning could cause nutritional deficiencies.
| 1 month | 2-3 months | 6 months-3 years | 4-6 years | 7-10 years | Adult |
| 115 Kcal / kg | 100 Kcal / kg | 96 Kcal / kg | 90-80 Kcal / kg | 80-60 Kcal / kg | 30-40 Kcal / Kg |
In the first year of life, 85-90% of the caloric intake is used for the maintenance of the basal functions and for growth, while only 10-15% is reserved for the expenses deriving from the physical activity. In the adult, however, this latter percentage rises to 20-30%, while the basal metabolic rate drops to around 65-70%.
Protein requirement
The rapid growth, which goes against the young organism, means that the protein requirements, and in particular of essential amino acids, are much higher than those of an adult, where the nitrogen balance is in balance.
| 0-1 year | 2-4 years | 5-12 years | Adult |
| 2-1.8 g / kg of body weight | 1.4 g / kg of body weight | 1.2 g / kg of body weight | 0.9 g / kg of body weight |
Lipid requirements
Hand in hand with protein requirements, even those of lipids reach their maximum value in the first weeks of life. These nutrients are in fact necessary, among other things, to build adipose reserves, synthesize some regulatory substances, transport fat-soluble vitamins and build plasma membranes. Although it has not been exactly quantified, it is very important to satisfy the need for essential fatty acids (naturally present in breast milk and added to the artificial milk preparation process).
| 0-1 year | From 2 years | From adolescence to adulthood |
| 45-50% Kcal. tot | 30% Kcal. tot | 25-28% Kcal. tot |
Needs for carbohydrates
In the first years of life the energy requirement is largely spent for the maintenance of the basal metabolism, since the movements are limited and the maximum body growth. Therefore more proteins and lipids are needed to synthesize the new body structures, but less carbohydrates (which represent the classic fuel for muscular work, scarce in the newborn).
| 0-1 year | From 2 years to adulthood |
| 45-50% Kcal.tot | 60-65% Kcal.tot (Of which 12-15% simple sugars) |
Fiber requirements
In the first year of life, the supply of fiber is limited by the need not to hinder the intestinal absorption of nutrients and the inability of the newborn to consume other foods outside of milk and few baby products.
In pediatric age the recommended daily amount of fiber, expressed in grams, can be easily calculated with the "age plus five" rule (age in years + 5), introduced by Williams ( Child Health Center of the American Health Foundation, 1995 ).
For a child of one year, 5 + 1 = 6 grams of fiber per day are therefore required, which will be provided mainly by fruit and vegetables in baby food or in the first baby food.
Vitamin and mineral requirements
During the first months of life there is a progressive depletion of iron stocks accumulated by the child during fetal life. To avoid deficiencies of this mineral, the pediatrician may suggest different strategies, such as the introduction of foods enriched with vitamins, iron and other minerals or the prolongation of breastfeeding. This last hypothesis, if feasible, also prevents the risk of the child going against calcium deficiencies caused by the brusque from a milky diet, and therefore rich in this mineral, to a non-milk one. Alternatively, foods rich in calcium (milk and derivatives) or specific supplements can be introduced.
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