Composition of Breast Milk and Commercial Formulas
Amy Tobey
FCSC 430 George Fox University
Composition of Breast Milk and Commercial Formulas
While many consider breast milk to be the only option when it comes to feeding their newborn infant, I wanted to see what the differences were between what women produce naturally and what is being produced for them by manufacturers. What are the benefits of breastfeeding, and what are the benefits of a formula based diet? How do the nutrients provided by each compare? And is one just as good as the other, or is human milk still the best thing we can give to our newly born under normal circumstances?
Endorsed by multiple public health organizations, breast milk has long been hailed as the best food source for infants (Institute of Medicine, Committee on the Evaluation of the Addition of Ingredients New to Infant Formula Staff, 2004). “Human milk is unquestionably the gold standard for infant nutrition. Ideally, the healthy, term infant experiences direct, exclusive breastfeeding; the milk itself and the act of feeding provide many advantages…” (Biancuzzo, 2003, p. 431) Because of the over 200 components in breast milk, and the diversity of the human body, nutrients and calories in the milk vary greatly and can be linked with time of day, mother’s diet, how much time the feeding has taken, and how often the baby gets fed (Dewar, 2008).
It is important to note that the body changes the composition of the milk throughout lactation (Dewar, 2008). “Mature breast milk looks very different from colostrum, the milk produced in the first few days after birth. According to Guthrie (1989), each 100 mL of colostrum yields approximately: 58 calories, 5.3 g carbohydrates, 2.9 g fat, and 3.7 g protein.” (Dewar, 2008) The high beta carotene content in colostrum gives it a yellow hue (Dewar, 2008). Vitamin E and zinc are also very concentrated in mother’s milk at this time (Dewar, 2008). Throughout the first week, the fat and lactose content of the milk goes up while the protein, vitamin, and mineral content go down (Dewar, 2008). These changes continue until the milk reaches the mature state at 21 days after conception (Dewar, 2008).
One study of British moms showed their milk to be composed of 70 calories, 89.97 grams of water, 7.4 grams of carbohydrates primarily in the form of lactose, 4.2 grams of fat, and 1.3 grams of protein (Dewar, 2008).
The majority of the calories of breast milk come from fat, but this fat varies throughout the course of the day, as well as each feeding (Dewar, 2008). “The fat content of human milk increases during a single nursing session. As a full breast empties, the milk it produces becomes more fatty.” (Dewar, 2008) The more often a baby is fed, the higher the fat content of milk the breast will produce and the less likely the baby will suffer from vitamin deficiencies (Dewar, 2008). Long chain fatty acids may help in brain development, and one, docosahexanoic acid (DHA), helps to make the myelin sheath that insulates nerve fibers (Dewar, 2008). Cholesterol is another important element of fat important for brain maturation that can only be found in breast milk as formulas have yet to include it (Dewar 2008).
Anyone who has experienced a baby spitting up dinner knows that milk separates in their little stomach. Milk has two proteins responsible for this, casein (which turn into curds) and whey (Dewar 2008). 60% of the proteins in breast milk are whey while most infant formulas are high in curds making it harder to digest them (Dewar, 2008). Proteins not only serve to build muscles and bones, but also protect against pathogens as is the case with immunoglobulin A, a protein that defends against repertory issues, intestinal parasites, and bacteria (Dewar, 2008).
Breast milk also contains cholesterol, calcium, sodium, phosphorus, vitamin C, magnesium, zinc, pantothenic acid, iron, nicotinic acid, iodine, vitamin A and copper in addition to other vitamins and minerals, hormones, and agents to fight disease (Dewar, 2008). Clearly, breast milk is the perfect food for infants.
Busy mothers who want to take advantage of this high nutrient food are presented with a bit of a challenge. Although pumping breast milk is an option for the busy mother who wants to give her child the best nutritional start possible, some nutrients do leave the breast milk with storage.“Milk that is not promptly fed to infants may be altered. First, storage can diminish some of the components of the milk. Even if milk is not exposed to extremes in temperature, exposing it to light results, within three hours, in a 50% reduction in riboflavin content and 70% loss of vitamin A. Second, pathogens may enter stored milk.” (Biancuzzo, 2003 p. 432) Clearly, it’s not ideal, but it will do in a pinch. Breast milk is best served straight from the mom to the baby with no stops in between.
While breast milk is a wonderful source of nutrients, even this may not be enough for a premature baby. The smallest of babies often times cannot get all the nourishment they need from their moms. In this case, a helping hand is required. “…Very-low-birth-weight (VLBW) infants will need to have mother’s milk “modified” in some way; for example, the infant may need expressed milk with an added fortifier. The fortifier may be added to either fresh or previously stored milk... Generally, fortifiers are indicated when the infant’s birth weight is less than 1500 g… When VLBW infants can tolerate human milk at greater than 100 ml/kg/day, supplementation using a human milk fortifier is started.” (Biancuzzo, 2003, p.432) In these cases, formulas work together with breast milk to keep the most vulnerable babies alive.
Unlike VLBW’s, most healthy full term babies will not need any vitamin supplements to enjoy the full benefits of their mother’s milk (Biancuzzo, 2003). However, supplementation may be necessary in the following instances. To prevent hemorrhaging in infants, a vitamin K supplement is administered at birth to all infants (Biancuzzo, 2003). Vitamin D deficiency is rare in breastfed infants, but can occur if the mother is not getting enough vitamin D herself and keeps the baby from exposure to the sun (Biancuzzo, 2003). Supplements of vitamin D currently are only available mixed with vitamin A and vitamin C in the form of drops (Biancuzzo, 2003). Vitamin B-12 deficiencies may occur in breastfed infants whose mothers are strict vegetarians, and vitamin B-1 deficiencies can also occur in babies whose moms are malnourished, especially in developing countries (Biancuzzo, 2003). Finally, 6% to 20% of breastfed babies are at risk for low iron stores after the first four months of breastfeeding (Biancuzzo, 2003). Although breast milk is generally lower in iron concentration than traditional formula, the iron in it is more bioavailable making the little go a long way (Biancuzzo, 2003).
Breast milk can be enhanced in overall proteins, vitamins, and fatty acids by taking prenatal vitamins, eating proteins, limiting saturated fats, eating fish, breastfeeding when the baby is asking for milk, and making sure each breast has been emptied before switching (Dewar, 2008). Also, there are some risks involved with breastfeeding. Aside from nutrient deficits already discussed, infants are at risk of being exposed to toxins from their mother’s milk including legal and illegal drugs, infectious pathogens, and AIDS (Institute of Medicine, Committee on the Evaluation of the Addition of Ingredients New to Infant Formula Staff, 2004).
Formula has been hailed as a more viable source than cow’s milk for infants in regards to its nutrient balance, and promotion of growth and development in infants (Institute of Medicine, Committee on the Evaluation of the Addition of Ingredients New to Infant Formula Staff, 2004). “Infant formulas do not duplicate the components of breast milk exactly;...the exact composition of breast milk has not yet been fully established. Rather the goal of infant formula is to match the function of breast milk in regard to meeting the infant’s nutritional needs… There is no set, immutable recipe for infant formulas. With the passage of time, new technologies immerge and new ingredients gain credibility.” (Pray, 2010)
Formula manufacturers change their recipes when prompted by science to do so to make their product more closely conform to the properties of breast milk (Institute of Medicine, Committee on the Evaluation of the Addition of Ingredients New to Infant Formula Staff, 2004). They do this by adding new ingredients, but this can be more complicated than one might guess (Institute of Medicine, Committee on the Evaluation of the Addition of Ingredients New to Infant Formula Staff, 2004). “In the simplest example, nutrients that are present in both milks may be present in different ratios. For many nutrients that do not interact chemically or compete for enzymatic or receptor binding sites, the relative amounts many not be important. However, in situations where there is competition for enzymes or receptor binding sites in the intestine, the relative proportions may have biological significance.” (Institute of Medicine, Committee on the Evaluation of the Addition of Ingredients New to Infant Formula Staff, 2004)
So what is infant formula made of and how does it meet the nutritional needs of the infant? Infant formulas come in liquids that are ready to use and powders that must be diluted with water or reconstituted in preparation for a feeding (Pray, 2010). Formulas are made of water, carbohydrates fat, protein, vitamins, minerals, and other ingredients (Pray, 2010). “FDA requirements specify minimum amounts of 29 separate nutrients and the allowable maximum amounts for 9 of the nutrients. Manufacturers usually set nutrient amounts that safely exceed the FDA minimums (without exceeding the maximum levels) and this practice allows the formula to meet its label claims up to its expiration date.” (Pray, 2010)
Water, carbohydrate, proteins and fats are essential nutrient sources for all humans. Formulas are 85% water regardless of whether they are ready to use or must have water added (Pray, 2010). If too much water is added, the baby can end up with water intoxication, and too little water can result in diarrhea, dehydration, renal failure, gangrene of the legs, and coma (Pray, 2010). In light of this, it is important to prepare formulas according to the manufacturers specifications. Water should also be boiled for at least a minute before using in formula to make sure it is sterile (Pray, 2010). “Carbohydrates are a major source of energy for an infant’s brain, muscles, and other tissues. Lactose is the standard carbohydrate in milk-based formulas and lactose-free formulas contain such carbohydrates as glucose polymers, sucrose, corn syrup solids, tapioca starch, and modified cornstarch.” (Pray, 2010) Protein is present in milk based formulas as casein and whey while soy isolate is preferred for infants with special medical needs (Pray, 2010). Fat is given to babies on formula in the form of corn oil, soy oil, safflower oil, and coconut oils (Pray, 2010) However, there is some debate on the quality of the fat being received via formula. “Human milk fat is more bioavailable than the vegetable oils found in infant formulas.” (Institute of Medicine, Committee on the Evaluation of the Addition of Ingredients New to Infant Formula Staff, 2004)
There are other elements included in formulas as well. Vitamins and minerals are generally supplied according to what is recommended for a healthy baby and should not be supplemented unless the caregiver is instructed to do so by a medical physician (Pray, 2010). Prebiotics and probiotics are sometimes added to support good digestive health (Pray, 2010). “Carnitine must be added to all infant formulas to aid in fat oxidation. It is found naturally in formulas prepared from human milk and cow’s milk but must be added to soy-derived formulas…Nucleotides are found in breast milk , and are the fundamental building blocks of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), as well as adenosine-5’-triphosphate (ATP). Their addition to infant formula may aid in the proper development of the gastrointestinal tract and enhance overall immune function.” (Pray, 2010)
Formula is harder for infants to digest than breast milk and therefore allows for longer periods between feedings (Pray, 2010). In addition to this, formulas are built so that all nutrients are included in their composition, eliminating the need for further supplementation (Pray, 2010). The FDA has strict standards for the formulas on the shelves in the US, and all manufacturers must meet these standards in order to have a piece of the market share in this country (Pray, 2010).
So, all the jargon aside, how do breast milk and formulas really compare when we are looking at the overall nutritional composition? A cow’s milk based formula is 8 to 9% protein, 41-43% carbohydrate, and 45-50% fat according to babyfoodchart.com’s nutrient composition of formula chart. The same website states that breast milk contains 6% protein, 40-45% carbohydrate, and 50% fat. The wonder of breast milk is that it changes with the child’s nutritional needs. The mother’s body senses what the baby needs and then produces that for the child. A formula cannot adapt like that because it’s not a living organism. It comes in a can. So, while both will feed a child and provide nutrition for the growth of the baby, the quality of food that comes from breast milk cannot be matched by a formula.
References
Biancuzzo, Marie (2003). Breastfeeding the Newborn: Clinical Strategies for Nurses. St. Louis, MO: Mosby.
Dewar, Ph.D. Gwen (2008). Nutrients and calories in breast milk. Parenting Science. Retrieved February 6, 2012, from http://parentingscience.com/calories-in-breast-milk.html
Institute of Medicine (U.S.), Committee on Evaluation of the Additional Ingredients New to Infant Formula Staff (Contributor) (2004). Infant Formula: Evaluating the Safety of New Ingredients.Washington D.C.: National Academic Press. doi: http://site.ebrary.com/lib/georgefox/Doc?id=10060399&ppg=63
Pray, PhD, DPh, W. Steven (March 15, 2010). Infant Formulas: Safe Alternatives to Breast Milk in Many Situations. USPharmacist.com. Retrieved February 6, 2012, from http://www.uspharmacist.com/continuing_education/ceviewtest/lessonid/106527/
Very interesting read, Amy! Thanks for posting!
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