Formulas have traditionally been based on the milk of some other mammal. In the United States, the milk most commonly use is that of the cow. Empirically, formulas were developed using whole or evaporated milk, sugar,and water. Even affter sterility, e.g. boiling, evaporated, condense ,or acidified, was achieved problems became obvious. The high phosphorus content of such formulas led to seizures (4). Factors in the milk,including is low iron content, led to anemia. The high protein content was associated with azotemia (5). The high electrolyte content led to dehydration or hyperelectrolytemia. Its butterfat was rather poorly absorbed (6), and frequently led to diarrhea. The carbohydrate that was added was usually not lactose, and this led to decreases in absorption of some nutrients (7). In order to preserve sterility, excess sugar was added in condensed milk, and led to protein deficiency, or lactic acid (8) was added and was associated with infantile acidosis.
At the same time that these changes were occurring, the importance of vitamins was recognized and vitamins C and D were added, resulting in elimination of rickets and scurvy. More recenty, the importance of iron and zinc were recognized, and the addition of these has led to a decrease in incidence of deficiency of these elements.
In the past 30 years, formulas which more closely approximate the composition of human milk. The protein content has been decreased to about 1.5g/dl. The butterfat has been removed and vegetable oils added. These not only supply essential fatty acids, but also improve fat absorption. Casein, Which is low in sulfur- containing amino acids, has been reduced and whey proteins increased in ratio similar to that in human milk. Lactose has been added as the only supplemental carbohydrate. Formulas are fortified with iron, zinc, and multiple vitamins.
Futher changes in formulas can be expected as analyses of breast milk and breast fed infants continue. Recent studies indicate that the caloric consumption of many breastfed infants is considerable less than previously documented (9). The factors responsible for the metabolic efficiency of the breastfed infants if found should lead to applicability not only to infants but to others.
Supplemental food
With the wider use of formulas in past, supplemental foods were introduced at younger and younger ages. Part of this practice was due to the recognition formulas then available were probably deficient in trace nutrients. Part was akso due to a developing fad. The early introduction of supplemental foods is frequently associated with discontinuance of breast or formula feeding. Whole cow’s milk is then substituted. Because of its ease of administion, it may be offered as a beverage without realization that it is a food. It then is consumed in excessive amounts leading to deficiencies of certain nutrients like iron and zinc, and in some children anemias may be responsible for learning difficulties and irritbility (10).
With better studies of neurophysiological development,(Table 1) the trend at present is to withold supplements in either the breast- or bottle-fed infant until 4-6 months (11). Not only is the swallowing mechanism better developed, but in the allergic reactions infant, breastfeeding benefits are prolonged