Thursday, June 22, 2006

Breast Milk

Last week in the New York Times Science section, there was an article that reported on a national breast-feeding awareness program that is suggesting that not breast-feeding your children is tantamount to negligence. Now, I'm all for breast feeding, I think it probably is the best food for an infant. However, I think there is also lots of misinformation about why breast feeding is good.

One of the reasons I often hear is that breast milk confers extra immunity to the infant. I get this from everyone including pediatricians and scientists, and it also appeared in that Times article. The argument stems from the fact that breast milk contains immunoglobulins and lymphocytes. Well, let's think about this more clearly. Immunoglobulins or antibodies are proteins and digestion breaks proteins down into amino acids. That is why pharma always tries to develop small molecule drugs. Protein-based drugs must be injected. You can't take them orally. Now, in certain mammal species, neonates possess pathways to transport proteins in breast milk directly into the blood stream. The jury is still out on humans but it looks like we're not in that category. So, I'm sorry to say, your baby is probably not getting extra antibodies from breast milk.

So why should a baby be breast fed? One thing that has been found is that the microflora of breast-milk fed babies differ significantly from formula-fed babies. You're body has more bacterial cells than it's own cells so having the right mix of micro-organisms is very important. I think this is the main reason we should push breast milk. Establishing the correct microflora environment is probably crucial for digestion and fending off infections. Additionally, the contents of breast milk will vary depending on what the mother eats. Formula always tastes the same. Breast fed babies have been known to prefer what their mothers eat and to have more diversity in their food preferences in general. Cultural tastes may partially be propagated through breast feeding. Also, babies seem to control the amount they eat much better with breast feeding than with a bottle. That may partially be because parents encourage their babies to finish each bottle even if the baby is already full. The bottom line is that their are many benefits to breastfeeding but obtaining antibodies is not one of them.

13 comments:

Hedi Soula said...

Breast feeding is indeed mammal business. It was probably selected for good reasons. For example in cow, the amount of fat in the mother's milk implies directly the size and the development of the brain of the calf. It should be possible to detect real benefits of breast feeding because your long term benefits seem to me a bit awkward. I will never breast feed anyone (because i'm a male) and certainly won't impose anybody to breast feed her baby; this is the mother's choice and in many cases (social ones) it is not possible for the mother to feed her baby that way. Then I wonder if there are any studies of the effect of breast feeding for the mother and science should definitely find a way to increase the amount of benefits of non-breast milk.

Carson Chow said...

Hi Hedi,

There are actually many studies of the benefits of breast feeding for both mother and baby. Babies follow different growth curves, develop cognitively faster, and so forth. Mother's lose weight faster and perhaps have some protection against breast cancer. The benefits I stated in the post are all based on data. I chose those because I wanted to a) dispel the immunoglobulin myth, and b) find something that I thought would be difficult for formula to reproduce. New formulas are very close to breast milk nutritionally but microflora depends on so many other things besides nutritional content.

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Anonymous said...

As a lucky mother, I can add a reason: when breastfeeding works well, it is easier and cheaper and (apart from the first week/weeks) actually very pleasant.
As for the social reasons, I have breastfed during a particularly long faculty meeting. Improving formula is good, but we shouldn't forget to change society as well.

Carson Chow said...

Thanks for your post. Cost is certainly a factor and it is sad that the propensity to breast feed goes down with income. I think changing society to make it easier for mothers to breast feed is very important. In particular, I think providing rooms and time for pumping at work should be encouraged.

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Carson Chow said...

Actually, I didn't even notice the survey post!

I suppose you're right but my guess is that there is a scam in there some where.

cc

Carmen said...

It is a well proven scientific fact that breast milk does in fact contain antibodies. These antibodies are used by the baby to build the child's immune system. This is why breastfed babies don't get sick as often as formula-fed infants. Case in point: I've had two cases of the flu two months apart. My daughter, who continued to nurse while I was sick, did not herself get anything worse than some loose stools. The antibodies I made in my milk from being sick were passed directly to her to protect her.

Seriously, where did you get your information? Breast milk has been tested many times, and it highly anti-bacterial, which is why once pumped it can sit out for 10 hours without refrigeration. You can't do that with formula unless you want it contaminated. Scientific test after test has been performed proving the immunological benefit of breast milk to formula. It's one of the top reasons sited in defense of breastfeeding, and is not a myth.

Get your facts straight, and maybe look at the research done.

Here are five antibodies scientifically proven to be found in breast milk: IgG, IgA, IgM, IgD and IgE.

Perhaps you should look them up.

Scientific American did a nice article on these antibodies in milk. I strongly suggest you read it.

Carson C. Chow said...

Hi Carmen,

I didn't say that breast milk didn't have antibodies. In fact, it clearly does, which is precisely what I wrote. What I said was, it is unknown if it is possible for the antibodies to enter the baby's bloodstream. Please read my post again.

Carson

Doc said...

Intestinal Absorption of Immunoglobulins by Newborn Infants. Archives of Disease in Childhood 1972;47:411-414

Carson C. Chow said...

Thanks for the reference, Doc.

K. said...

http://books.google.com/books?id=iepqmRfP3ZoC&pg=RA1-PA797&lpg=RA1-PA797&dq=antibody+endocytosis+in+gut+from+milk&source=bl&ots=-BG6oUkM9z&sig=t4-5OdsIIeB7PPNcVLj3qGtMwvc&hl=en&ei=TDnhSr6LOYil8Aa7wMn3AQ&sa=X&oi=book_result&ct=result&resnum=2&ved=0CBQQ6AEwAQ#v=onepage&q=antibody%20endocytosis%20in%20gut%20from%20milk&f=false

According to Alberts Molecular Biology of the Cell, fig. 13.60, antibodies from milk in the gut (at least of a rat) bind to specific receptors and are endocytosed / transcytosed through cells and released into the newborn's bloodstream...

Carson C. Chow said...

Yes, it is established for rats but I believe there are some mammals for which this is not true.