Monday, August 24, 2009

Iron out the iron wrinkles

I have never believed the hysteria about making sure your baby has enough iron because come 6 months old they cannot get enough iron from breast milk. Plane and simple mums have been feeding for millenniums without any issues, so why is it a problem today?

Well was doing some submission on the Food Relation Policy for Infant formula Products. It turns out that bioavailability of iron in breast milk is 8.12%. This seems like a very small amount, until you read that in whey dominate formula the bioavailability is 1.28%, casein formulas 0.48% and soy based formula 1.48%. (1)

This changes the argument somewhat! Because formula should have approximately 5 to 16 times the amount of iron as breast milk to get equivalent uptake.

Now what is the level in breast milk, the following graph (2) is very helpful
So the lowest iron level is approximately 0.3 micro g/ml. So using the absorption figure of 8% as mentioned above, the iron uptake is 0.3 x 8% which gives 0.072 micro g/ml. 

Low iron formula is milk which has iron levels below 6.7 micro grams per ml. These iron levels are typically much lower than 6.7 normally being 1-2 micro g/ml(3). Therefore the iron from whey formula would be 2 X 1.28% resulting in iron uptake of 0.027 micro g/ml.

Thus you can see that mothers milk, even at the lowest level or 0.3 micro g/ml can supply significantly more iron to baby than low iron formulas.

In America a high iron formula has iron levels >6.7 micro g/ml and in generally they have 10-12 micro g/ml. Thus in whey formula baby gets 0.13-0.15 in whey formula and 0.05-0.58 micro g/ml. The breast milk figures is still 0.072 micro g/ml. Therefore in high iron formula's mum is still providing more than the casein formula, and about half the iron in whey formula.

In Europe the iron levels are typically 4-7 micro g/ml. This gives in whey formula a level between 0.05 - 0.89. This is very similar to the iron levels from the breast milk.

Thus we can conclude that breast milk delivers to baby more than any casein dominated formula. For whey casein formula is the iron level is below 7 micro g/ml, that is levels found in low iron formula, or formula for Europe it is the same, or less than iron from breast milk. The only formula that gives more iron than breast milk, is the high iron American formula that is made from whey (or soy, but I don't like soy milk, will blog about that one day)

It should be noted that the above information is not applicable if mother carrying the baby has not enough iron in the last trimester of pregnancy, thus baby post birth may have lower iron levels than what is optimal.

(1)Bosscher D, Van Caillie-Bertrand M, Robberecht H, Van Dyck K, Van Cauwenbergh R, Deelstra H. J. In vitro availability of calcium, iron, and zinc from first-age infant formulae and human milk. J. Pediatr Gastroenterol Nutr. 2001 Jan;32(1):54-8.
(2) Jensen (ed) Handbook of Milk Composition, Academic Press, 1995 pg 628
(3) Policy Statement Iron Fortification of Infant Formulas PEDIATRICS Vol. 104 No. 1 July 1999, pp. 119-123

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