Baby formula

Human milk is the preferred means for feeding the newborn human infant for the first four to six months of life. It has been considered for a long time by nutritionists that the best food or nutrition supplied to an infant is its own mother’s milk; i.e. fresh human milk. Breastfeeding with human milk has multiple beneficial effects on the infant. First, it is known to be the most suitable diet for infant’s nutritional requirements. The human milk provides the infant with immune protection against a wide range of infection related diseases. Third, as it contains active insulin molecules it protects the infant against the development of Type-1 diabetes (2-3). Fourth, insulin present in breast milk enhances small intestinal growth and development. It is recognized, however, that many situations arise wherein the infant cannot be fed mother’s milk and as a result synthetic infant milk formulas, predominantly based on cow’s milk, have been prepared and used to nourish an infant. The American Academy of Pediatrics recommends that babies be breast fed if possible. Unfortunately, for reasons ranging from illness and exhaustion to the need to immediately return to work after having the baby, many mothers have no option other than to formula feed.

The development of substitutes for maternal milk is an integral part of the history of pediatrics. Baby formulas have been developed to replace or to supplement human milk when breast-feeding is inadequate, unsuccessful, or when a mother chooses not to breast feed. Attempts of improving infant formula composition have focused on more closely simulating the composition of breast milk. There are many different infant nutritional formulas that are commercially available or otherwise known in the infant formula art. These baby formulas comprise a range of nutrients to meet the nutritional needs of the growing infant, and typically include lipids, carbohydrates, protein, vitamins, minerals, and other nutrients helpful for optimal infant growth and development. These formulas are typically derived in part from cows milk or from soy protein isolates or concentrates. Ideally, the composition of the infant formula would be exactly the same as the composition of human milk. Because infant formulas are typically made with cow milk (and sometimes soy protein), on a molecular level, these formulas are not the same as human milk. Nonetheless, infant formulas are designed to mimic the formulation of human milk as much as possible. Furthermore, baby formulas are required to contain nutrients as listed by governmental standards or by responsible organizations as requested by governmental authorities. The resultant infant formulas are sometimes called “humanized milk”, “simulated human milk”, “simulated mother milk”, “simulated breast milk” and “infant nutritional formula”.

The composition of human milk serves as a valuable reference for improving infant formula. However, human milk contains living cells, hormones, active enzymes, immunoglobulins and components with unique molecular structures that cannot be replicated in infant formula. The protein systems of human milk and cow’s milk differ substantially, both quantitatively and qualitatively. Unlike human breast milk, infant formula must remain stable on the shelf for up to thirty-six months. These fundamental differences between human milk and infant formula often mandate differences in the composition to achieve similar clinical outcome. Infant formulas are derived, to a large extent, from cow’s milk. After being diluted, the cow’s milk is enriched with whey proteins, diverse carbohydrates, such as lactose, dextrin, maltose and starches, different mixtures of vegetable and animal fats, vitamins and minerals. Human breast milk has an average composition in percentages by weight 87.5 water, 12.5 total solids, 1.0-1.5 protein and non-protein nitrogen compounds, 3.0-4.0 lipids, 7.0-7.5 carbohydrates and 0.2 ash. Cow milk has an average composition in percentages by weight 87 water, 13 total solids, 3.0-4.0 protein, 3.5-5.0 lipids, 3.5-4.0 carbohydrates and 0.7 ash. Cow milk is low in taurine, about 4 .mu.moles percent. With respect to carbohydrates, lactose, the disaccharide of galactose and glucose, occurs both in cow and in human milk and the lipids of human and cow milk are chiefly triglycerides dispersed as very small globules. The principal proteins of cow milk are caseins, representing about 82% of the protein nitrogen. When cow milk is centrifuged and the cream skimmed off the top and the remaining fluid, skim milk, acidified, casein is precipitated. The resulting supernatant liquid or fluid is whey which contains about 18% of the total protein in cow milk. Alpha-lactalbumin, a protein found in the milk of all mammals, is a major protein in human milk. Beta-lactoglobulin is absent from human milk. The protein content of bovine whey contains about 50% to 55% of beta-lactoglobulin and about 18% of alpha-lactalbumin. The ratio of beta-lactoglobulin to alpha-lactalbumin in bovine whey ranges between 2.5:1 and 4:1.

There are three general classes of formulas commercially available for babies on the market: those based on milk, those based on soy proteins, and those based on hydrolysates of casein, a milk protein. Normally, full-term infants are usually fed cow’s-milk-based formulas which contain a mixture of casein and whey as protein sources and they provide nutrition for infants, however they do not provide a protein concentration and an amino acid profile equivalent to that of mother’s milk. In addition these standard formulae are not suitable for pre-term infants and those having adverse reactions to protein in cow’s milk formula or to lactose. An alternatives to cow’s milk formula is soy formula; particularly for infants who are lactose intolerant. However, soy is not as good a protein source as cow’s milk. Also, infants do not absorb some minerals, such as calcium, as efficiently from soy formulae. A further alternative formula is based on hydrolysed protein. These formulas are hypoallergenic and have a decreased likelihood of an allergic reaction. Vegetable protein-based infant formulas containing no milk protein or carbohydrate are also in wide use. The soy based formulas have been developed to provide adequate nutrition for the infants that cannot tolerate lactose or are allergic to milk proteins. The casein hydrolysates have been further developed for children who do not digest protein well or who suffer from malabsorption or poor eating habits. Alpha-lactabumin is one of the two proteins required for lactose synthesis. Other important constituents of cow milk whey are the immonoglobulins which carry the antibodies; these account for about 10% of the whey protein. Human milk contains not only much less protein than cow milk, but the distribution of proteins is different. Infant milk formulas based on cow milk, particularly the protein content or components thereof, have been prepared such that the protein content has been modified such that the protein content of the formula is 60% whey protein and 40% casein protein.

As a consequence of the differing amounts of the specific whey proteins in bovine milk and human milk and the amino acid compositions of these proteins, bovine milk and human milk differ substantially in their amino acid profiles. Beta-lactoglobulin is particularly rich in the essential amino acids valine and threonine. Alpha-Lactalbumin is particularly rich in the essential amino acids tryptophan, lysine and cystine compared to other bovine milk proteins. Many infant formulas contain isolated milk proteins, isolated vegetable proteins or protein hydrolyzates, from different origins such as casein, lactalbumin, soy and meat. Also, these baby formulas have one or more carbohydrates (sucrose, dextrin, maltose and starch), mixtures of diverse kind of fats, minerals and vitamins, to meet not only the healthy newborns’ nutritional requirements, but also of infants and children with clinical symptoms of lactose intolerance, protein intolerance and, in general, with diverse malabsorption-malnutrition syndromes.

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May 25, 2008 | Filed Under Baby nutrition