Organic, free-range eggs less likely to carry salmonella (but no guarantees)

September 7th, 2010 |

I admire your usually objective and scientific approach to nutrition – a subject that clearly needs such an approach.

However, you clearly have a bias in this case and it shows.

Even a quick look at the literature tells you that the incidence of Salmonella infection can be dramatically cut by immunization of chickens against this bug. In fact, some studies that have looked at this factor noted that far more free-range chicken were immunized than caged production chickens, so some of the lower incidence of infection will undoubtedly be due to that.

Immunizations also explain the large variations in incidence of Salmonella– something that you again fail to mention. So there will be flocks of non-free-range chicken whose eggs as just as safe as that of free-range chicken because of the immunizations.

And while looking at the issue of Salmonella infections, one should also mention the well-known fact, shown by study after study, that the incidence of parasitic gastrointestinal infestations/worms is MUCH higher amongst free-range chicken than cage-kept chicken. While one would think that this is only in 3rd world countries, unfortunately this is not the case. One of the larger studies comes from Denmark, in an organic free-range system much like we have in North America.

The story only gets worse from here! Free-range eggs have a higher risk of having too high levels of dioxins and dioxin-like polychlorinated biphenyls because these are pollutants that the chicken would pick up from the soil and environment. In fact, one study concluded that “Available data show that current soil levels of dioxins and DL-PCB in residential and agricultural areas in Europe often appear to be too high to produce free-range eggs with dioxin levels below the current limit values in the EU.” I doubt that our situation in North America is any better.

With respect to omega-3 fatty acid content being higher in free-range eggs; the ONLY study that has found that is from Mother Earth News. Hardly an unbiased source!!! On top of that, they did not publish details of their own study. I would like to see that study confirmed by others before placing much weight on it, no matter how attractive it looks to someone like you, who consumes free-range eggs.

There are in fact many other studies that did NOT find the omega-3 fatty acid content of free-range eggs to be higher. That is not surprising. If the omega-3 fatty acid content of free-range eggs was higher simply due the fact that they *are* free-range, why would the producers not seek permission to label their eggs as such from the regulatory bodies? It would be a relatively simple step to do, and NOT to do it would not make business sense.

Yet free-range eggs are not labelled as higher in omega-3 fatty acids. That’s because on average they are not.

There ARE eggs that are higher in omega-3 fatty acids, and they are of course labelled as such and command a higher price accordingly. However, this has nothing to do with them being free-range, rather, the chickens are being fed flax seed, the source of the higher omega-3 fatty acids. ONLY these eggs have been CONSISTENTLY shown to be higher in omega-3 fatty acids BY AN INDEPENDENT 3RD PARTY TESTER.

Important to also mention here is that the omega-3 fatty acid content of eggs also varies *significantly* by the breed of the hens (e.g. Araucana hens, vs Lohmann Selected Leghorn vs ISA Brown hens) – but not whether they are free-range or cage-kept.

Presumably, Mother Earth News, – hardly an unbiased source of information – compared an egg, one free-range one not, from *two different breeds of hens*! Unless you compare eggs from the same breed of hens, the results are meaningless and will be most certainly due to the breed type.

Don’t get me wrong; I am all for organic food and healther eating. But I am also for objective reporting and assessing of the literature.

References:
1. Prev Vet Med. 2008 Mar 17;83(3-4):323-36. Epub 2007 Oct 24. Salmonella in Belgian laying hens: An identification of risk factors. Namata H, Méroc E, Aerts M, Faes C, Abrahantes JC, Imberechts H, Mintiens K

2. Vet Rec. 2001 Dec 8;149(23):699-704. Environmental contamination and detection of Salmonella enterica serovar enteritidis in laying flocks.Davies R, Breslin M.

3. Avian Pathol. 2007 Jun;36(3):187-97. A longitudinal study of environmental Salmonella contamination in caged and free-range layer flocks.Wales A, Breslin M, Carter B, Sayers R, Davies R.

4. Mol Nutr Food Res. 2006 Oct;50(10):908-14. Contamination of free-range chicken eggs with dioxins and dioxin-like polychlorinated biphenyls.Schoeters G, Hoogenboom R.

5. Food Addit Contam. 2006 May;23(5):518-27. Carry-over of dioxins and PCBs from feed and soil to eggs at low contamination levels– influence of mycotoxin binders on the carry-over from feed to eggs. Hoogenboom LA, Kan CA, Zeilmaker MJ, Van Eijkeren J, Traag WA.

6. Poult Sci. 2006 Jun;47(3):294-300. Lipid profile in eggs of Araucana hens compared with Lohmann Selected Leghorn and ISA Brown hens given diets with different fat sources. Millet S, De Ceulaer K, Van Paemel M, Raes K, De Smet S, Janssens GP.