“Just One Bottle Won’t Hurt”—or Will It?

  • Posted by Marsha Walker, RN, IBCLC
  • The gastrointestinal (GI) tract of a normal fetus is sterile.
  • The type of delivery has an effect on the development of the intestinal microbiota.

* Vaginally born infants are colonized with their mother’s bacteria.

* Cesarean born infants’ initial exposure is more likely to environmental microbes from the air, other infants, and the nursing staff which serves as vectors for transfer.

  • Babies at highest risk of colonization by undesirable microbes or when transfer from maternal sources cannot occur are cesarean-delivered babies, preterm infants, full term infants requiring intensive care, or infants separated from their mother.
  • Breastfed and formula-fed infants have different gut flora.

* Breastfed babies have a lower gut pH (acidic environment) of approximately 5.1-5.4 throughout the first six weeks that is dominated by bifidobacteria with reduced pathogenic (disease-causing) microbes such as E coli, bacteroides, clostridia, and streptococci o babies fed formula have a high gut pH of approximately 5.9-7.3 with a

variety of putrefactive bacterial species.

* In infants fed breast milk and formula supplements the mean pH is approximately 5.7-6.0 during the first four weeks, falling to 5.45 by the sixth week.

* When formula supplements are given to breastfed babies during the first seven days of life, the production of a strongly acidic environment is delayed and its full potential may never be reached.

* Breastfed infants who receive supplements develop gut flora and behavior like formula-fed infants.

  • The neonatal GI tract undergoes rapid growth and maturational change following birth.

* Infants have a functionally immature and immuno-naive gut at birth.

* Tight junctions of the GI mucosa take many weeks to mature and close the gut to whole proteins and pathogens.

* Open junctions and immaturity play a role in the acquisition of NEC, diarrheal disease, and allergy.

* sIgA from colostrum and breast milk coats the gut, passively providing immunity during the time of reduced neonatal gut immune function.

* Mothers’ sIgA is antigen specific. The antibodies are targeted against pathogens in the baby’s immediate surroundings.

* The mother synthesizes antibodies when she ingests, inhales, or otherwise comes in contact with a disease-causing microbe.

* These antibodies ignore useful bacteria normally found in the gut and ward off disease without causing inflammation.

  • Infant formula should not be given to a breastfed baby before gut closure occurs.

* Once dietary supplementation begins, the bacterial profile of breastfed infants resembles that of formula-fed infants in which bifidobacteria are no longer dominant and the development of obligate anaerobic bacterial populations occurs. (Mackie, Sghir, Gaskins, 1999)

* Relatively small amounts of formula supplementation of breastfed infants (one supplement per 24 hours) will result in shifts from a breastfed to a formula-fed gut flora pattern. (Bullen, Tearle, Stewart, 1977)

* The introduction of solid food to the breastfed infant causes a major perturbation in the gut ecosystem, with a rapid rise in the number of enterobacteria and enterococci, followed by a progressive colonization by bacteroides, clostridia, and anaerobic streptococci. (Stark & Lee, 1982)

* With the introduction of supplementary formula, the gut flora in a breastfed baby becomes almost indistinguishable from normal adult flora within 24 hours. (Gerstley, Howell, Nagel, 1932)

* If breast milk were again given exclusively, it would take 2-4 weeks for the intestinal environment to return again to a state favoring the grampositive flora. (Brown & Bosworth, 1922; Gerstley, Howell, Nagel, 1932)

  • In susceptible families, breastfed babies can be sensitized to cow’s milk protein by the giving of just one bottle, (inadvertent supplementation, unnecessary supplementation, or planned supplements), in the newborn nursery during the firstthree days of life. (Host, Husby, Osterballe, 1988; Host, 1991)

* Infants at high risk of developing atopic disease has been calculated at 37% if one parent has atopic disease, 62-85% if both parents are affected and dependant on whether the parents have similar or dissimilar clinical disease, and those infants showing elevated levels of IgE in cord blood irrespective of family history. (Chandra, 2000)

* In breastfed infants at risk, hypoallergenic formulas can be used to supplement breastfeeding; solid foods should not be introduced until 6 months of age, dairy products delayed until 1 year of age, and the mother should consider eliminating peanuts, tree nuts, cow’s milk, eggs, and fish from her diet. (AAP, 2000)

  • In susceptible families, early exposure to cow’s milk proteins can increase the risk of the infant or child developing insulin dependent diabetes mellitus. (IDDM) (Mayer et al, 1988; Karjalainen, et al, 1992)

* The avoidance of cow’s milk protein for the first several months of life may reduce the later development of IDDM or delay its onset in susceptible individuals. (AAP, 1994)

* Sensitization and development of immune memory to cow’s milk protein is the initial step in the etiology of IDDM. (Kostraba, et al, 1993)

  • Sensitization can occur with very early exposure to cow’s milk before gut cellular tight junction closure.
  • Sensitization can occur with exposure to cow’s milk during an infection-caused gastrointestinal alteration when the mucosal barrier is compromised allowing antigens to cross and initiate immune reactions.
  • Sensitization can occur if the presence of cow’s milk protein in the gut damages the mucosal barrier, inflames the gut, destroys binding components of cellular junctions, or other early insult with cow’s milk protein leads to sensitization. (Savilahti, et al, 1993)


American Academy of Pediatrics, Work Group on Cow’s Milk Protein and Diabetes Mellitus. Infant feeding practices and their possible relationship to the etiology of diabetes mellitus.  Pediatrics 1994; 94:752-754

American Academy of Pediatrics, Committee on Nutrition. Hypoallergenic infant formulas. Pediatrics 2000; 106:346-349

Brown EW, Bosworth AW. Studies of infant feeding VI. A bacteriological study of the feces and the food of normal babies receiving breast milk. Am J Dis Child 1922; 23:243

Bullen CL, Tearle PV, Stewart MG. The effect of humanized milks and supplemented breast feeding on the faecal flora of infants. J Med Microbiol 1977; 10:403-413

Chandra RK. Food allergy and nutrition in early life: implications for later health. Proc Nutr Soc 2000; 59:273-277

Gerstley JR, Howell KM, Nagel BR. Some factors influencing the fecal flora of infants. Am J Dis Child 1932; 43:555

Host A, Husby S, Osterballe O. A prospective study of cow’s milk allergy in exclusively breastfed infants. Acta Paediatr Scand 1988; 77:663-670

Host A. Importance of the first meal on the development of cow’s milk allergy and intolerance. Allergy Proc 1991; 10:227-232

Karjalainen J, Martin JM, Knip M, et al. A bovine albumin peptide as a possible trigger of

insulin-dependent diabetes mellitus. N Engl J Med 1992; 327:302-307

Kostraba JN, Cruickshanks KJ, Lawler-Heavner J, et al. Early exposure to cow’s milk and solid foods in infancy, genetic predisposition, and risk of IDDM. Diabetes 1993; 42:288-295

Mackie RI, Sghir A, Gaskins HR. Developmental microbial ecology of the neonatal

gastrointestinal tract. Am J Clin Nutr 1999; 69(Suppl):1035S-1045S

Mayer EJ, Hamman RF, Gay EC, et al. Reduced risk of IDDM among breastfed children. The Colorado IDDM Registry. Diabetes 1988; 37:1625-1632

Savilahti E, Tuomilehto J, Saukkonen TT, et al. Increased levels of cow’s milk and blactoglobulin antibodies in young children with newly diagnosed IDDM. Diabetes Care 1993; 16:984-989

Stark PL, Lee A. The microbial ecology of the large bowel of breastfed and formula-fed infants during the first year of life. J Med Microbiol 1982; 15:189-203


  1. Sierra Sullivan

    So what does this mean for my baby? To my absolute utter dismay, my son had to be born via c-section after 24 hours on non-medicated labor. He was 9 pds. 11 oz. Right after the c-section my blood pressure crashed to 50/25 and they basically had to save my life. Because of this I was in ICU for two days and was not able to breastfeed or pump milk. On top of this I have type 1 diabetes and thyroid issues, both of which impact my ability to produce milk on my own. After two weeks and still not producing milk (we had to supplement with formula and donated breast milk), I started Motilium. At about two months old I was finally able to breast feed him exclusively. He is a little over 4 months old now. I guess I am scared by any damage done to him by the formula he had to drink while I was getting my own supply up. Does the fact that he's been breastfed exclusively for over two months now reverse any damage done to him in the first two?

    1. Cheryl Taylor

      I'm sorry you had such a tough beginning! Kudos to you for sticking it out and committing to getting breastfeeding on track. You can't undo the negative effects that are part of using an infant formula, but give yourself some credit that it was for a short time and you are giving a much longer period of positive effects from breastmilk. It doesn't reverse the effects but it sure does tip the scales positively more and more the longer you breastfeed!

  2. Jay LaRue

    "You can’t undo the negative effects that are part of using an infant formula" !!!

    On what basis can you claim this?

    The above article is a poorly written collation of convenient facts that only aims to make moms who do not breastfeed feel guilty. Clearly you are a supporter of this propganda, and can feel proud that you have succeeded in making Sierra feel bad about herself

    I had terrible problems with breastfeeding that were only made worse by healthcare "professionals" sending me on a guilt trip, upping my stress levels and making it even harder to breastfeed.

    Given the choice between trying to persevere wih breastfeeding when my child was clearly suffering from not getting enough nutrition, and using formula, then I would choose formula every time. Anything else would cause far more "negative effects"

    1. Cheryl Taylor

      It is very well documented that anything entering an infant's stomach other than breastmilk changes the gut flora. This article outlines the changes in gut flora, health and development that occurs with the introduction of a commercial infant formula into the GI system.

      I'm sorry that you did not get the support and accurate information needed to breastfeed when you were struggling to breastfeed your own infant. Having the accurate information and examining what may have contributed to getting off track with breastfeeding is an extremely valuable tool to progressing on to successfully breastfeed subsequent children. You may have done everything possible within your knowledge and experience to breastfeed, and you may have gotten help from a lactation consultant and they may have given you all they knew. It just may not have been the solutions that are possible. I would recommend to any pregnant woman to attend their local La Leche League meeting, establish relationships with the leaders and nursing moms in your area by attending meetings. It is of invaluable worth to have support that is available locally and that you have gotten acquainted with. I would also find out who the IBCLC's (Internationally Board Certified Lactation Consultants) in your area are in the event that there are difficulties with breastfeeding that require the help of the experts in the field. Many moms in the US have OB's and Pediatricians that do not have accurate breastfeeding knowledge and do not provide the help and support needed to new moms, or even worse give the wrong information and end up sabotaging the nursing dyad.

      Furthermore, as I responded to Sierra, while there are medical situations and emergencies that can cause a cessation of breastfeeding the mom can be encouraged that breastfeeding CAN be begun again, a supply brought in and/or increased, and exclusive breastfeeding can be returned to. Many moms don't realize that they can return to breastfeeding and that it greatly contributes to the health and development of their baby and is very worth the effort! I have seen many babies up to 6 months and older that have begun to nurse and eliminated formula. It absolutely can be done!

    2. Noel

      No one can *make* you feel guilty. You choose your own feelings. So if you feel guilty for not breastfeeding you’re bringing it on yourself. You can choose not to feel guilty you know? You are in charge of your own feelings.

  3. Jle

    I am so glad I read this, because now I have an idea of what probably happened to my baby. While we were in the hospital when I delivered her, they gave her 2 formula bottle without my consent, although I told the nurses that I was going to exclusively breastfeed her. Now we are dealing with these allergies issues, and specks of blood in her diapers. Do you think that I should sue the hospital for the damage they caused to my baby's health? Do you think that she will heal from it? I feel very sad about this situation, and disappointed of the medical staff at the hospital.

    1. Cheryl Taylor

      How old is your baby? Are you breastfeeding now? If you are seeing specks of blood in stooling now, and are breastfeeding, you need to eliminate all dairy from your diet. Do you see other signs of dairy reaction/allergy? Nasal congestion/mucus? eczema? colic? green stools?

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