The Scientific Benefits of Breastfeeding
Thursday, May 14, 2009 
There are a great many Web sites and studies out there that talk about the benefits of breastfeeding. Like much of the stuff on the Web, they have been written at different stages in time, may or may not have been updated, may be based on science or may be based on what someone heard from their neighbour. In short, you can't believe everything you read online.
Breast is best.
Or is it?
All of the major health authorities in the world say that it is. The American Academy of Pediatrics, Health Canada, the World Health Organization, and others are all on the bandwagon. But it has become fashionable of late to claim that breastfeeding isn't really all that beneficial. That the benefits are all overblown.
When I set out to sort through the mess, to find the truth, I started initially collecting bibliographies and lists of studies that I was going to try to scour through at some point if I had time. Not for myself. But to provide a voice of reason in the face of the naysayers.
Fortunately, a number of people that I know and a number of authorities on the topic pointed me to one wonderful study. The über-study of all über-studies. It is called Breastfeeding and Maternal and Infant Health Outcomes in Developed Countries (April 2007) and it was prepared by a team of investigators at the Tufts-New England Medical Center Evidence-Based Practice Center in Boston. This is what was included:
We screened over 9,000 abstracts. Forty-three primary studies on infant health outcomes, 43 primary studies on maternal health outcomes, and 29 systematic reviews or metaanalyses that covered approximately 400 individual studies were included in this review.
Not only is the methodology sound and the research extensive, but as the title indicates, this study is about health outcomes in developed countries. That means that we can put to rest the claims that breast is only best if you don't have access to clean water or enough money to buy formula.
So what are the real scientific benefits of breastfeeding?
I have summarized them below. If you want to see the full details on the number of studies that contributed to each finding, the degree of accuracy, and the quality of the studies, then read the full paper. This is intended only as a summary of the major conclusions.
The benefits to the child
There are a number of health benefits to the breastfed child, some of them are significant and others are less significant.For full term infants the benefits include:
- Acute otitis media (middle ear infections): Babies that were ever breastfed had a 23 percent lower incidence of acute otitis media than exclusively formula fed babies.
- Atopic dermatitis (type of eczema): In families with a history of atopy, exclusive breastfeeding for at least 3 months was found to have a 42 percent reduction in atopic dermatitis compared with breastfeeding for less than 3 months.
- Gastrointestinal infections: Infants who were breastfeeding had a 64 percent reduction in the risk of non-specific gastroenteritis compared with infants who were not breastfeeding.
- Lower respiratory tract diseases: There is a 72 percent reduction in the risk of hospitalization due to lower respiratory tract diseases in infants less than 1 year of age who were exclusively breastfed for 4 months or more.
- Asthma: Breastfeeding for at least 3 months was associated with a 27 percent reduction in the risk of asthma for those without a family history of asthma and a 40 percent reduction for those with a family history of asthma.
- Type 1 Diabetes: Breastfeeding for at least 3 months results in between a 19 and 27 percent reduction in incidence of childhood Type 1 Diabetes compared with breastfeeding for less than 3 months (findings confirmed through multiple studies, but some cause for caution in interpreting results).
- Type 2 Diabetes: Found a 39 percent reduction in risk of Type 2 diabetes later in life for people that were breastfed as infants (some cause for caution in interpreting results).
- Childhood Leukemia: Breastfeeding for at least 6 months associated with 19 percent decrease in risk of childhood acute lymphocytic leukemia and a 15 percent decrease in the risk of acute myelogenous leukemia.
- Sudden Infant Death Syndrome (SIDS): The meta-analysis found that breastfeeding was associated with a 36 percent reduction in the risk of SIDS compared to not breastfeeding. Another study completed since the meta-anlaysis was done found a 50 percent reduction in the risk of SIDS as a result of breastfeeding.
In the past, other claims have been made about the benefits of breastfeeding. However this study determined that some of those benefits were based on other factors that may be associated with a greater incidence of breastfeeding. This includes cognitive development (IQ), which is more likely to be tied to maternal intelligence, socioeconomic status and home environment. It also includes the obesity issue. People who were breastfed are less likely to be obese as adults, but it is not clear whether this is due to breastfeeding or other factors (e.g. being part of a series of healthy choices that a family makes). The risk of cardiovascular disease also does not appear to be lower in breastfed infants than in formula fed infants.
The benefits to the mother
Often people only talk about the benefits to the baby, but forget to talk about the benefits to the mother. Women that are having trouble breastfeeding and considering giving up should think about not only their child's health, but also their own health and weigh the short-term issues they are having with breastfeeding against the longer term potential health benefits. Those benefits include:
- Maternal type 2 diabetes: In women with no history of gestational diabetes, each additional year of breastfeeding resulted in a 4 to 12 percent reduction in the risk of maternal type 2 diabetes (only nurses included in these studies though, so interpreting results for general population must be done with care).
- Breast cancer: A reduction of risk of contracting breast cancer of 4.3 percent for each year of breastfeeding (one study) or 28 percent for 12 or more months of breastfeeding (another study). Another study that I reported on in Save Yourself, Save Our Health Care System, found that if women in Canada breastfed for at least 16 months over their lifetime, we could cut the breast cancer rate from 6 percent of women to 3 percent of women.
- Ovarian cancer: Breastfeeding results in a 21 percent decrease in the risk of ovarian cancer.
Like with the benefits to the infant, there were some frequently reported benefits to the mother that cannot be scientifically proven. One example is weight loss, where there is no clear evidence that breastfeeding mothers shed the weight more easily than formula feeding moms (but we can eat more chocolate bars!). Another example is osteoporosis, where there is no clear benefit from breastfeeding. Postpartum depression is a tricky area, since it is hard to determine cause-effect i.e. did women stop breastfeeding because they had PPD or did they have PPD because they stopped breastfeeding?
The naysayers
When she wrote The Case Against Breastfeeding, Hanna Rosin claimed to have plowed through the studies on breastfeeding and found that the benefits were scant at best. Unfortunately, a lot of people read her article and I have seen her claim now stated over and over again as a fact. The truth is that Hanna Rosin only read a select few studies on breastfeeding, in particular those that would support her claim that perhaps the benefits were scant. She did not do a comprehensive review of the literature on breastfeeding like the one that I cited above.
In my post on the Economics of Breastfeeding: A Cost-Benefit Analysis and the follow-up to that post, I mentioned a study called Maternal Employment, Breastfeeding, and Health: Evidence from Maternity Leave Mandates that claimed that "increased breastfeeding duration has had no effect on overall physical or psychological health outcomes of either children or mothers". That seemed like a very loaded statement that contradicted much of what I had read elsewhere, so I dug into it. A better way to phrase their result would have been this:
- Extending maternity leave rights in Canada led to women taking 3 to 3.5 months longer off of work on average.
- Most women in Canada breastfed both before and after the change in maternity leave policies.
- Despite most women initiating breastfeeding, both before and after the change in maternity leave policies few women in Canada met the recommended duration of breastfeeding.
- The change in maternity leave policies resulted in women breastfeeding for, on average, 1 month longer than they did before the leave policy was changed.
- It also resulted in an average increase of 1.5 months in the length of exclusive breastfeeding.
- This increase in the length of breastfeeding did not show improvements to the physical or psychological health of either children or mothers using data collected about mother/baby pairs for which the children were aged 7 to 12 months old and 13 to 24 months old at the time
Basically, this doesn't look at the difference between formula feeding versus breastfeeding. It doesn't look at significant increases in the length of breastfeeding. It doesn't look at long-term results of breastfeeding on the child or the mother's health.
While I support continued research on this topic, we need to be careful how the results are thrown around and be more specific about what was actually found.
Does this mean that breast is only?
Breast is not just best. In fact, breastfeeding should be the standard, the default. However, that doesn't mean it is right or even possible for everyone all of the time. So breast is not only. Stay tuned for my next post on the issue of choice and options in infant feeding.
Reader Comments (95)
Thank you so much for sharing this article :) It helps me to encourage more moms to breastfeed their babies and to give more information about it :)
In my case, i came from a non-breastfeeding family and they do discouraged me not to breastfeed my child, so it's hard to find someone to give me an advice or information about breastfeeding.
I'm so glad and so thankful to God that i breastfed my child for almost 4 years and i don't have any problem at my child's health :) So...why we waste for God’s given food for our precious babies? God’s creation has its own perfection if we compare to human creation.
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The research that I want to see, and have been looking for, is when to start solids. I think a lot of the benefits and arguments of breastfeeding vs. formula feeding overlook the fact of when parents start solids. With a leaky gut until 7 or 8 months of age, starting solids at 4, 5, or 6 months (or at 3 weeks like my mother-in-law with my poor husband) will often lead to a sickly baby. I think there is a strong correlation between America's horrible rate of ear infections and the societal norm of starting solids "between 4 to 6 months". 80% of the immune system is in the gut, so it makes sense that if you start solids too early, it will lead to the breakdown of the immune system. So I am wondering how much of the research took into account when babies were began on solids. Also, breastfeeding women tend to not worry as much about solids and will often delay giving solids until 7-9 months of age. I have personally found that women who formula feed will often give rice cereal at 4 months, processed baby jar food at 5 months, and the baby is eating table food by six months. These are often the children that have tubes in their ears by 18 months. I think the societal and cultural norm of starting solids at the magical age of 6 months needs to be challenged and re-evaluated. The research is out there in lactation journals, etc, but no one is talking about it. I think for the sake of the health of our children that this needs to be addressed. I know that this exclusively breastfeeding mother of a nine month old is definitely tired of hearing, "So when are you going to feed him some 'real' food?"
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Great post. It's crazy how different times bring different theories. It's tough to know what's backed by scientific research and what's not. Thanks for the great info!
[...] infants to thrive — but when entire societies substitute artificial milks for the real deal, we can absolutely see the negative ramifications. Yes, even in industrialized countries such as the USA. ↩ 8 November 2010 at 12:56 am | [...]
I'm still not so sure that your data is anymore thought out than Hanna Rosin's data and that is why I'm so frustrated with this topic. I wish that women had sound clinical trials to rely on that aren't overshadowed by emotion and personal opinion. I'm currently in my Labor and Delivery clinical rotation and I've never met a group of more biased and judgemental women in my life. I just wish that as women we had more sound data to rely on that wasn't created or published by such a biased group of healthcare professionals. Decisions to breastfeed shouldn't be based on guilt and made to feel shameful because others believe it is the best method of feeding.
If anyone is aware of any sound head to head studies that are available please let me know. I can't help but wonder if the increased infections is more to do with the bottles and preparation techniques (such as not hand washing, nipple washing or possibly shape of the bottle nipple causing more otitis media) than the type of milk inside. I would love to see a head to head study of breastmilk in bottles compared to formula in bottles because that would tell us if the benefits are really the milk.
Formula Milk vs Human Milk:
Human milk is perfectly made for humans. It is easily digestible, and the leaky gut is not a problem. Human milk contains over 400 nutrients. It also contains cholesterol, which is vital for the development of the nervous system. Human milk has been shown to fight cancer cells. It also contains stem cells. And of course, a ton of antibodies that help fight bad bacteria. It is a living food, constantly changing to suit the babies individual needs.
Formula milk is dead food. It is considered survival food (much like the canned food stored in survival basements.) It contains just the basic nutrients for survival. It does not contain cholesterol. It does not contain stem cells, antibodies, etc. Formula-fed babies need to start solids at about 6 months, even though their gut is not closed and it would be better to start solids at 9 months. Breastfed babies do not need solids until after the first year, but formula is so inadequate babies need solids by the 6th month, especially solids containing cholesterol. (I highly recommend egg yolk for this).
There are a ton of studies showing the differences between formula milk and human milk.
There are many who are constantly lobbying that breastmilk should be the norm - that we should rely on breastmilk banks, and throw formula in the garbage where it belongs. Formula is a billion dollar industry, with WIC in the USA buying 66% of formula.
Babies would be much better off if we put breastmilk in the bottle instead of the dead food of formula. If a woman thinks it is "gross" to put someone else's breastmilk in a bottle for their baby or to even breastfeed in general, then they are putting their own bigoted opinions as more important than their baby's health. We need more education for the masses, especially in human milk banks, and nursing in public. America's bigoted opinions towards breastfeeding have got to change for the health of our nation.
MelissaN:
May I ask where you are getting this information from? My understanding is that a breastfed baby's gut closes sometime between four and six months and that a formula fed baby's gut closes much earlier than that due to the formula ingestion, but that it isn't a good thing for it to be closing earlier. If you have different information, I would be interested in reading it.
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Great article, thank you! I just have one comment: as you were mentioning that breastfeeding / breastmilk should be the norm why are you still talking about "benefits" for baby and mother?
AndreaS:
There are a lot of things that are the "norm" and are beneficial and there are plenty of other things that are the "norm" and are detrimental. I think that we need to talk about breasteeding as the norm while also continuing to ensure people understand why it needs to be the norm.
[...] If human milk is a sound strategy for child survival, we would expect breastfed babies to be healthier than their non-breastfed counterparts. Indeed, the Agency for Healthcare Research and Quality (AHRQ) concluded in 2007 that breastfed babies were healthier. (For more on the controversy surrounding breastfeeding’s benefits see PhD in Parenting.) [...]
Can someone pls point out to me how formula is *harmful exactly? I was in the hospital for a month with intense infections and thrombosis and so my breastfeeding attempts failed due to interruption with major antibiotics and sever depression from not being with my baby. My 5-month old has now been on formula since week 2, and the extreme guilt that I feel is enhanced by these articles which state that formula will harm my child - it is causing great distress for me. I would like to state however, that the bond I have with my baby now is very strong - to the point where I was stopped in the mall by a woman who said she could see it in our interaction, so I do not believe that formula = less bonding (I cried for that entire month because nurses kept telling me it would most likely be affected).
[...] People spreading rumours about formula being just as healthy as breastfeeding. It isn’t. [...]
@Doc - nice to hear a lone voice of reason on this.
Something I feel like is missing from your analysis of these scientific findings though is that the studies showing X% of children who were breast fed dont get X are correlative not causal conclusions. Empirically, this does not prove that breastfeeding makes babies healthier, but that babies who breast fed had a lower incidence rate of X disease. To date, there has never been a study that "proves" breastfeeding is the sole reason these babies were healthier (it could be that those mothers made better health choices). To do that, they would have to do a controlled human study which will never happen on infants. All of this is to say, there has never been any study that has been able to locate or pin point what makes breastfeeding "best" or that can prove that it is. If you asked any of those researchers, they would say there was a correlation, which is different from breastfeeding causing metabolic changes.
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I am glad that you point out also the benefits of breastfeeding for the mother. People usually tend to underestimate them. Great post!
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I'm new to exploring your site, so perhaps this is in another post I haven't yet found, but are you aware of studies showing that expressed breast milk is healthier than formula? Pumping, especially exclusively pumping, is so mentally and physically taxing for the women I know who do it (not to mention extraordinarily time consuming), and pretty much all of the information I can find conflates breast milk with breastfeeding. It's not clear to me so far that bottle feeding breast milk has actually been shown to be better than bottle feeding formula.
Thankfully we all have a choice of what to do with our bodies and what doesn't work for us. Sadly those who so enthusiastically promote bf and condemn those who chose not to, go on to feed their kids McDonald's and Coke later on in life. I believe that is far worse than not ever bf your children.
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The problem with these claims is that they are unscientific; i.e. they simply equate correlation with causation, with no proof that the actual breast-milk is actually responsible for these benefits-- when there easily might be other environmental factors associated with mothers who breast-feed, which can lead to these benefits-- such as simply spending more time with the baby at home, rather than a "Supermom" dragging the baby around with them in a rush, leaving the baby unattended often or with a sitter etc.
The only real advantage of bottle-feeding is convenience and anonymity, i.e. anyone can bottle-feed a baby, and it's easier to do anytime in public etc., so bottle-fed babies may be more neglected or abused than breast-fed babies.
I'm surprised that with all the controversy, there hasn't been a more scientific study commissioned; however the the Baby-Formula lobby has a vested interest in propaganda.
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I find it hilarious how flippant you are about how socioeconomic backgrounds and home environments aren't factored into the study.
GI upsets, respiratory infections and asthma are massively effected by environs and poor socioeconomic backgrounds tend to be the worst...
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I suggest everyone starts by reading the conclusion of the metastudy you refer to. I quote
"...A history of breastfeeding is associated with a reduced risk of many diseases in infants and mothers from developed countries. Because almost all the data in this review were gathered from observational studies, one should not infer causality based on these findings..."
The author goes into suggest further Studies that are required and acknowledges the shortcomings of the studies to date.
The important words from the above conclusion are 'associated' , 'observational studies' and 'one should not infer causality'. In basic language this means there 'appears' to be a benefit but this has not been 'proven' .
It is almost always the case that pro breast feeding campaigners read the bits that they want to read and ignore the parts they don't. If you want to breast feed then do so, but if you don't then don't, but in any event do either safe in the knowledge that there is no 'causal / direct evidence' to prove one is significantly better than the other.
I am so glad I found your article. I have a 13 month old baby girl that I am still brestfeeding and plan to until she is 2 (or her or I am done with it). I am starting to feel aware of people noticing my baby is one and still nursing, I feel judged, as though I should be done nursing her; as though she is too old now. So, I wanted to do some research to arm myself with facts for these naysayers. I have known that WHO suggests breastfeeding until age 2 but I wanted to know why. while researching I came across The Case Against Breastfeeding, and I hated it! I think about all the mothers who have read it and don't think breastfeeding is imiportant. I just want to say thank you for doing such in depth research and portraying the findings accurately, which can be hard to do.
My situation has always been: by the time I feed the baby, leave baby with a sitter, go out, and order drinks, I’m usually buzzed just as it’s time to pump. My supply was never such that I could skip or delay a feeding. So I do feel as though there’s a place for pump and dump.
For some mothers who suffer postpartum depression the added stress involved with breastfeeding and her inability to call upon her partner or other caregiver to help feed the child will likely cause significant distress and potentially harm an already strained relationship with the infant.
My wife often felt guilt-tripped by well intentioned healthcare professionals who actively discouraged her from even using a breast pump. This guilt did not help her recovery.
While breast feeding may be best, healthcare professionals should consider why a woman is unwilling to breastfeed before insisting.
I'd like to quote the abstract from the study: "Because almost all the data in this review were gathered from observational studies, one should not infer causality based on these findings."
The benefits cited here are correlated but have not been proven to be caused by breastfeeding. I think, regardless of one's position on breastfeeding, that the study has been grossly misrepresented in this article.