Absence of homogenization might explain the benefits of raw cow's milk

Abstract

van Neerven et al1van Neerven R.J.J. Knol E.F. Heck J.M.L. Savelkoul H.F.J. Which factors in raw cow's milk contribute to protection against allergies?.J Allergy Clin Immunol. 2012; 130: 853-858Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar discuss the factors in raw cow's milk that might contribute to protection against allergies. However, it is possible that it is not the presence of factors in raw milk, but rather the absence of a factor in processed milk—specifically homogenization—that is responsible for the “protection.” The fat globules in raw milk are 3.3 μm in average diameter and are composed of triglycerides surrounded by a milk fat globule membrane made of phospholipids and protein. In raw milk, these fat globules, which are more buoyant than water, rise to the surface and form cream. Homogenization of treated cow's milk prevents this separation by forcing the milk under pressure through very narrow tubes, resulting not only in a decrease in the average fat globule diameter from 3.3 μm to 0.4 μm but also a 600-fold increase in the total number of fat globules and an approximately 10-fold increase in their total surface area.2Goff D. Homogenization of milk and milk products. 2010. Available at: http://www.foodsci.uoguelph.ca/dairyedu/homogenization.html. Accessed October 31, 2012.Google Scholar The tremendous increase in total surface area results in the attraction of proteins to the surface of the new smaller fat globules.2Goff D. Homogenization of milk and milk products. 2010. Available at: http://www.foodsci.uoguelph.ca/dairyedu/homogenization.html. Accessed October 31, 2012.Google Scholar This close association of proteins with lipids has implications for the intralymphatic absorption and immunologic presentation of those proteins.3Wang Y. Ghoshal S. Ward M. deVilliers W. Woodward J. Eckhardt E. Chylomicrons promote intestinal absorption and systemic dissemination of dietary antigen (ovalbumin) in mice.PLoS ONE. 2009; 4: e8442Crossref PubMed Scopus (44) Google Scholar In murine studies, homogenized cow's milk is more likely than raw milk to both induce sensitization and provoke allergy symptoms on challenge.4Poulsen O.M. Hau J. Kollerup J. Effect of homogenization and pasteurization on the allergenicity of bovine milk analysed by a murine anaphylactic shock model.Clin Allergy. 1987; 17: 449-458Crossref PubMed Scopus (51) Google Scholar, 5Poulsen O.M. Nielsen B.R. Basse A. Hau J. Comparison of intestinal anaphylactic reactions in sensitized mice challenged with untreated bovine milk and homogenized bovine milk.Allergy. 1990; 45: 321-326Crossref PubMed Scopus (30) Google Scholar Because smaller lipid-protein conjugates have better transdermal absorption than do larger particles,6Kalluri H. Banga A.K. Transdermal delivery of proteins.AAPS PharmSciTech. 2011; 12: 431-441Crossref PubMed Scopus (131) Google Scholar the decrease in the size of homogenized cow's milk fat globules may also have implications for the transdermal sensitization hypothesis of Lack.7Fox A.T. Sasieni P. du Toit G. Syed H. Lack G. Household peanut consumption as a risk factor for the development of peanut allergy.J Allergy Clin Immunol. 2009; 123: 417-423Abstract Full Text Full Text PDF PubMed Scopus (299) Google Scholar And because IgE promotes facilitated antigen presentation leading to the production of IgE to different epitopes,8Aalberse R.C. Science from a black box.J Allergy Clin Immunol. 2012; 130: 902-903Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar early IgE production to such a major food source could act as an initiator allergen, promoting allergy in general. Which factors in raw cow's milk contribute to protection against allergies?Journal of Allergy and Clinical ImmunologyVol. 130Issue 4PreviewSeveral epidemiologic studies have shown that growing up in a farming environment is associated with a decreased risk of allergies. A factor that correlates strongly with this effect is the early ingestion of unheated cow's milk. Although, to date, no controlled studies on raw milk consumption have been performed to formally demonstrate this effect, several factors in bovine milk have been described that might explain how raw cow's milk consumption can decrease the risk of allergies. In addition, increasing knowledge on the immunologically active factors in breast milk have also contributed to our understanding of the effects of bovine milk in infants because many of the factors in bovine milk are expected to have functional effects in human subjects as well. Full-Text PDF ReplyJournal of Allergy and Clinical ImmunologyVol. 131Issue 3PreviewMiller1 stated in his correspondence in response to our Rostrum article that it is possible that it is not the presence of factors in raw milk, but rather the absence of homogenization, that might explain the protective effect of farm milk consumption. Full-Text PDF