Breast Milk or Bottled Formula? The Pros and Cons of Each

Over the last century in the United States, the decision on whether to breastfeed or bottle-feed our infant children has become complicated and controversial.1 Delving into why this controversy exists and what makes it so complicated, as well as examining both sides of the argument, go beyond the scope of this article (though the history of this controversy is quite interesting and may be worth a read).1-3 All the same, choosing between breastfeeding, bottle-feeding, or a combination of both is a decision that must be made by all new mothers. The nutritional content and other health benefits of breast milk and bottled formulas should be carefully weighed against their downsides, according to the individual needs of each mother and child, before a decision on which option is most suitable should be made. Here we present the pros and cons of both methods of infant feeding according to the available evidence.


The American Academy of Pediatrics (AAP) recommends breastfeeding over formula feeding as the sole source of nutrition for infants the first six months or so of their life, stating this recommendation is based on the “unequivocal evidence that breastfeeding protects infants against a variety of diseases and conditions.”4

Breast milk comprises a mix of proteins, fats, vitamins, and carbohydrates.5 The protein in breast milk is around 60 percent whey protein and 40 percent casein. This balance of proteins offers substantial protection from infection and allow the baby to digest the milk quickly and easily.5

Lactose, the primary carbohydrate in breast milk, aids in decreasing unhealthy bacteria in the stomach. It also improves calcium, phosphorus, and magnesium absorption.5

The vitamins and minerals found in breast milk are linked to the mother’s nutrient consumption. Therefore, mothers who are deficient in certain vitamins and minerals should take supplements to enhance the nutritional quality of their breast milk. For example, women who follow a vegetarian or vegan diet should consider taking a vitamin B12 supplement, which can help to prevent neurological damage in the baby that a deficiency in B12 might cause.6 Very little iron is found in breast milk, so when a baby is four months old, the United States Centers for Disease Control and Prevention recommends administering a daily iron supplement, 1mg for each kg of body weight, to infants on breast milk.7 Likewise, breast milk contains very little vitamin D, so the AAP recommends a supplement of 400 IU per day for infants.4

The AAP recommends exclusive breastfeeding for six months, followed by breastfeeding with complementary foods until the child is at least 12 months old.4

Benefits. Breast milk is free, does not require planning, preparation, or bottles/nipples or other equipment, and is always fresh and available. Along with meeting baby’s nutritional needs, breastfeeding has been shown to lower baby’s risk for several illnesses and diseases, including asthma, Type 1 diabetes, ear infections, and gastrointestinal infections. Breastfeeding also lowers the mother’s risk for breast cancer, ovarian cancer, Type 2 diabetes, and high blood pressure.4,8

Challenges. Breast-fed babies typically take in less milk per feeding, compared to formula-fed babies, which means they will likely require more frequent feedings—This can place more burden on the mother since the mother cannot share the responsibility of feeding with anyone else, unless she pumps and stores her milk  (see Breast Pumping sidebar). Additionally, some mothers find breastfeeding physically uncomfortable, even painful. Another challenge is that the quality of breast milk is directly related to the mother’s health and nutritional status, and can also be affected by medications she is taking.0

According to the AAP, there are a few medical conditions in which breastfeeding is not recommended. These include the presence of certain metabolic disorders in the infant (e.g., classic galactosemia—an inherited condition in which the body is unable to properly digest a sugar found in all foods that contain milk); certain viral infections in the mother (e.g., human T-cell lymphotropic virus Type I or II, untreated brucellosis, active tuberculosis, HIV); and active illicit drug use in the mother.4 In these cases, alternative feeding methods may be recommended. It’s important to note that in some cases of material HIV or narcotic dependence (e.g., when the mother is being treated with methadone), the risks that breastfeeding poses to the infant may be outweighed by its health benefits).4,8 

Formula Feeding

In cases where breastfeeding is not recommended, is not possible, or simply is not preferred, formula feeding can be an excellent source of nutrition for your infant. In the United States, FDA-approved, commercially prepared formulas contain sufficient fats, proteins, vitamins, minerals, and carbohydrates.0

Many formulas contain additional nutrients (e.g., iron) that are lacking in breast milk; thus, formula-fed babies do not need to take additional vitamin and mineral supplements.11 Most infant formulas are cow-milk based. However, alternative plant-based options are available (e.g., soy-based) for those with allergies or rare metabolic disorders, such as galactosemia, as well as specialized formulations designed for infants with specific disorders or special needs (e.g., premature infants). Like breastfeeding, it is recommended that babies drink formula for the first six months or so of life, followed by a combination of bottle-feeding with complementary, age-appropriate foods until the child is at least 12 months old.8

Benefits. Infant formula provides certain nutrients that breast milk lacks, meaning that babies who drink formula do not to take need extra supplements. Bottle-feeding also allows other people to feed the baby, which means the mother does not have to be around the baby at all times. Infant formula is not affected by the mother’s health, medications, or nutritional intake. And finally, formula takes longer to digest, so babies who drink formula often need to be fed less often than their breastfed peers.10,,12

Challenges. Infant formula is expensive and requires planning (e.g., refrigeration, access to clean water) and preparation (e.g., measuring, mixing, clean nipples and bottles). Bottled formulas are not as easily digested as mother’s milk, which may present nutritional and gastrointestinal challenges to some infants. Bottled formulations do not contain the natural antibodies and nutritional complexities found in breast milk that can protect the infant against infections and diseases. Bottle formulations do not offer the mother the healthful benefits of breastfeeding (e.g., reduced risk of certain cancers, Type 2 diabetes, high blood pressure). Bottle formulations are associated with increased risk of allergy, Type 2 diabetes, obesity, ear infections, and gastrointestinal infections in the infant.0 

Bottom line

Various factors influence the decision to breastfeed or formula feed. New moms should consider their personal circumstances and consult their doctors before choosing the method that is right for them. 


1.   Rothman L. Desperate women, desperate doctors and the surprising history behind the breastfeeding debate. 31 Jul 2018. Time Magazine site. Accessed 3 Aug 2021.

2.  Caron C. Breast-feeding or formula? For Americans, it’s complicated. 14 Jul 2018. New York Times site. Accessed 3 Aug 2021.

3.  United States Office of the Surgeon General; Centers for Disease Control and Prevention; Office on Women’s Health. Barriers to breastfeeding in the United States. In: The Surgeon General’s Call to Action to Support Breastfeeding. Rockville, MD: United States Office of the Surgeon General; 2011. Accessed 3 Aug 2021.

4.  American Academy of Pediatrics. Policy statement: Breastfeeding and the use of human milk. Pediatrics 2012;129(3):e827-e841.

5.  American Pregnancy Association website. What’s in breast milk? Accessed 22 Jul 2021.

6.  CDC website. Maternal diet. Reviewed 8 Oct 2020. Accessed 22 Jul 2021.

7.  CDC website. Iron. Reviewed 21 Sept 2020. Accessed 22 Jul 2021.

8.  American Academy of Pediatrics.Formula feeding. site. Accessed 3 Aug 2021.

9.  Nemours Kids Health. Breastfeeding vs. formula feeding. Last reviewed June 2018. Nemours Children’s Health site. Accessed 3 Aug 2021.

10. Cleveland Clinic website. The benefits of breastfeeding for baby and for mom. Reviewed 1 Jan 2018.–for-mom. Accessed 22 Jul 2021.

11  Stanford Children’s Health website. Infant nutrition. Accessed 22 Jul 2021.

12  MedlinePlus website. Breastfeeding vs formula feeding. Updated 17 May 2017. Accessed 26 Jul 2021.    

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