Breast Feeding and Intelligence: new scientific data

Breast feeding, for a long time seen as a bad thing, has made a resurgence in recent years in America for many reasons. Science has suggested many benefits from breast feeding including a better immune system, higher intelligence, a happier baby, and better mother-child bonding.

The overall benefit of breast feeding, when possible, are pretty clear. And it is important to keep this in mind. Breast feeding is NOT EASY. Contrary to what many expect, the process is not easy or automatic and can be quite painful and frustrating for both mother and child. Hence the need for "lactation consultants" and such. But if it can be worked out between mother and baby, it is well worth the effort.

What is less clear is WHY it is more beneficial. The initial breast milk provides antibodies that protect the child right at the beginning. But that is a fairly brief benefit. There are clear later benefits that CORRELATE with breast feeding, but it is hard to find the CAUSATION behind that correlation.

One example is the observation that in the developed world (I am unaware of studies that look cross-culturally) there is a positive correlation between breast feeding and intelligence.

Based on this, a friend of mine at UCLA did some research in rats where they looked at different formulas vs. breast milk diets. Their data suggested that there are fatty acid in breast milk that are vital to brain development that are not in formula. This is very likely since formula traditionally was not made with the specific fatty acid composition in mind. I think some effort has been made by some formula manufacturers to take these studies into account when they make their formula.

But a new study shows that these data may not be so applicable to humans. From Salon.com:

Breast-fed children are more intelligent than their bottle-fed counterparts, but this has nothing to do with the content of the milk they receive, a study published in the British Medical Journal said...

Researchers, who analyzed data from more than 5,000 children and 3,000 mothers in the United States, found that mothers who breast-feed tend to be more intelligent, according to a study published Wednesday on the journal's Web site.

"When this fact was taken into account, most of the relationship between breast-feeding and the child's intelligence disappeared," said Jeff Dar, one of the report's authors...

The researchers found that children who were breast-fed did better on IQ tests, but this was because their mothers were more intelligent, better educated and able to provide a more stimulating home environment.

Part of the research methodology included testing pairs of siblings, for whom feeding habits differed.

"Comparing two people from the same family like this is a good way of getting results that are less affected by family background. This confirmed the earlier results -- the breast-fed child was no more intelligent," Dar said...

Dar said though his team's study found no link to intelligence, breast-feeding was "definitely the smart thing to do," because of other benefits to both mother and child, including a stronger ability to ward off infections, respiratory illnesses and protection against developing allergies.

It is hard to reconcile the older studies that show specific fatty acids are important for brain development with this study that shows the correlation boils down to genetics. But science is complex and sometimes it takes time to reconcile two seemingly contradictory studies. Both studies are well done and are giving a piece of the puzzle.

It does all come down to choices based on information. It is very clear that breast feeding is beneficial. It is also very difficult for some mothers. Each mother has a choice and that choice should be based on the best information.

So Yay Science!

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