|Image 1: Better make sure your "mother's milk" (the milk you drink while you or your significant other are pregnant) is full fat!|
Milk allergy or allergy due to the lack of full-fat milk - is that the question?
Yet while the Zunquin study is by no means the only scientific evidence that nature's original meal replacement, irrespective of whether or not it may be "intended for human consumption" can exert potent health effects (cf. Barfray. 2003), the pros and cons of a high(er) intake of dairy is still a matter of constant debate. Other than within the paleosphere, the public and scientific debate does yet usually revolve around the notion of low- vs. high fat dairy, with the common recommendation to "choose low fat dairy in order to avoid the unhealthy saturated fats that come with the full-fat variety".
Nasty Insights into the Yo-Yo-Effect: Lower Body Fat Sticks and From Fit2Fat There's no Easy Way Back!"), the reduced absorption and presence of fat-soluble nutrients and the necessity to add sugar or artificial flavors, as well as chemicals to modify the taste and mouth-feel of those watery low-fat dairy products, a recent study from Department of Nutrition at the Harvard School of Public Health in Boston does now provide compelling evidence that either one or all of the former aspects, or a hitherto not elucidated difference between skim and full-fat dairy products increases children who are born to mothers who consume >5 portions of semi-skimmed milk per week during their pregnancy have an 8% increased risk of developing childhood asthma and a 40% increase in risk of developing allergic rhinitis later in life (Maslova. 2012).
|Table 1: If you are interested in other sources of CLA (and omega-3), in general, and the difference between grass- and grainfed beef, in particular, check out this table from a Daley et al. (Daily. 2012)|
"dose–response was present for semiskimmed milk intake, while any intake of full-fat yoghurt appeared to be protective of child asthma" (Maslova. 2012)that did, just as the aforementioned results, remain significant, even when the data was adjusted for the intake of other allegedly beneficial foods (fruit and vegetables) and nutrients (vitamin E, vitamin D, Se, Zn from diet and supplements).
So are those the CLAs and other ruminant trans-fats?
While Malsova et al. fail to give a clearcut answer on what the underlying reasons for these observations are, their detailed analysis of the data does yield some evidence that CLAs and other ruminant trans-fatty acids cannot explain the differences, as they showed similar correlations with both full-fat and semi-skimmed milk intake and were "not associated with either the early or later childhood outcomes" (Maslova. 2012).
|Image 2: Not, not all full-fat milk drinkers worked on a farm ;-)|
The diversity and complexity of our results make it difficult to interpret and propose a single agent mechanism, yet the consistent associations with low-fat yoghurt for later childhood outcomes suggest that compounds specific to this food, such as artificial sweeteners, may play a role.Interestingly, they specifically refer to the use of aspartame as the "primary" artificial sweetener in the Danish food supply since the 1980s, but cite a - at least in my humble opinion - highly biased source (Gideon. 2010) on that issue without even providing a single scientific study that would implicate aspartame as a factor involved in the etiology of asthma (+my brief research shows, there is none).
As far as the underlying mechanisms are concerned this leaves us with but one relatively certain conclusion: The scientists' initial hypothesis that ruminant trans-fatty acids could play a causal role in the development of allergic disease development cannot be upheld in view of the inverse associations Maslova et al. found between the CLA content and the risk to develop asthma and/or allergic rhinitis across products with different fat content.
A note on additional data evaluated in the study: The scientists make use of the actual hospital admissions due to asthmatic reactions as another source for their study data. Unfortunately, those only contribute to the already confusing results, because they suggest that despite the fact that the incidence of early childhood asthma is lower (other data), the chance to end up in hospital, as assessed by data from the Danish National Patient Registry appears to be higher in children born to mothers with a high full fat milk intake (+30%), and minimally reduced for children whose mothers consumed the same amount of skimmed dairy - it is however questionable how reliable this 3rd hand data which had to be linked back to the central person registry first and ran through multiple processing steps actually is (same for data from the Register of Medicinal Product Statistics).
|Image 3: Too much statistical shenanigan involved in the ER data for my liking.|
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- Bartfay WJ, Davis MT, Medves JM, Lugowski S. Milk whey protein decreases oxygen free radical production in a murine model of chronic iron-overload cardiomyopathy. Can J Cardiol. 2003 Sep;19(10):1163-8.
- Daley CA, Abbott A, Doyle PS, Nader GA, Larson S. A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef. Nutr J. 2010 Mar 10;9:10.
- Gideon B (2010) Aspartam: Nu også i ikke ‘Light’ produkter. < http://infowars.dk/content/aspartam-nu-ogs%C3% A5-i-ikke-light-produkter > last accessed on July 10, 2012
- Maslova E, Halldorsson TI, Strøm M, Olsen SF. Low-fat yoghurt intake in pregnancy associated with increased child asthma and allergic rhinitis risk: a prospective cohort study. Journal of Nutritional Science (2012), vol. 1, e5.
- Zunquin G, Rouleau V, Bouhallab S, Bureau F, Theunynck D, Rousselot P, Arhan P, Bougle D. Iron and exercise induced alterations in antioxidant status. Protection by dietary milk proteins. Free Radic Res. 2006 May;40(5):535-42.