By Ken Perrott 18/01/2016


The other day I came across the article Why Is Breast Milk So Low in Iron? It’s a fairly brief but sensible article discussing the problem of  the risk of iron deficiency in breastfed babies written by a research scientist with a PhD in nutrition – Alice Callahan.

She asks the question – Why would breast milk have evolved to be deficient in iron, putting babies at risk for iron deficiency? And provides some sensible answers from an evolutionary perspective.

These answers include the suggestion most babies are born with enough iron stores to last them the first few months of life and perhaps breastfeeding was originally less extended than it sometime is today. In the past, the umbilical cord was probably not cut as rapidly as it is today thus allowing for the increased transfer of iron from the mother. Babies also probably ingested iron from soil.

As she said:

“We must remember that breast milk evolved over the last 2-2.5 million years to enhance infant survival (and also not put the mother at risk) in the context of the conditions of the time.  In the developed world, there have been major changes in living conditions over just the last several hundred years, and evolution simply doesn’t happen that quickly.”

“Thinking about breast milk from an evolutionary perspective helped me to realize that my breastfed baby, who is not raised in the dirt and had her cord clamped immediately after birth (not the plan, but that’s a story for another day), might need a little help getting enough iron in her diet.”

I note she did not draw the superficial conclusion that the low concentration of iron in breast milk is proof that iron is not necessary for human nutrition – or even that it is toxic to humans. In fact, it seems silly that I should even mention this as a possible reaction. I only do so because this is the conclusion Paul Connett, a well-known anti-fluoride campaigner, has drawn from the relatively low concentration of fluoride in human milk.

In fact, that motivated reasoning is a central argument that Connett has been repeating for years. As he wrote recently:

“But what struck me most was that through all the twists and turns of evolution, starting in the sea where the level of fluoride is 1.4 parts per million, very little fluoride has ended up in mothers’ milk (0.004 ppm). Why on Earth — if dentists were correct that babies needed fluoride for healthy teeth — did nature provide so little to the new-born baby? It seems reasonable that nature is protecting the baby from this toxic substance during its early development.”

Leaving aside the fallacious appeal to nature, and the perception of “nature” as an “intelligent designer,” Connett’s argument is wrong because it is naive – a naivety surely derived from his confirmation bias. An objective person with a scientific doctorate would surely recognise the world is far more complex than his argument implies.

In fact, some of the arguments Dr Callahan provides for an evolutionary perspective on the low concentration of iron in human milk could be just as valid for fluoride. As she says:

“It is not surprising in our modern world that humans, and especially babies, sometimes need some nutritional assistance  to make up for the fact we no longer live in the environment we evolved in.”

So much for Connett’s naive fallacious appeal to nature, and his perception of “nature” as an “intelligent designer.”