Gluten Peptides in Human Breast Milk: Implications for Cow’s Milk???
Bottom line: A very small number of published studies report finding peptides in exceedingly small amounts (measured in parts per billion) in human breast milk. If dairy cows are fed wheat, barley, and rye grain (not a common occurrence from what I’ve been told) and if they have the same difficulty digesting (breaking down) gluten protein as humans, it is reasonable to wonder if gluten peptides may be found in cow’s milk too. However, based on testing, no significant amounts of gluten peptides have been detected in cow’s milk. As a result, individuals with celiac disease should not be concerned that cow’s milk contains harmful amounts of gluten.
Background: Over the past two years there have been numerous blog posts about “high” amounts of gluten in human breast milk. This has led to some speculation (as well as outright “this is fact” statements) that cow’s milk may contain gluten. Consequently, I have received questions regarding whether this is true.
Research articles on gluten in human breast milk: Based on searches of Pub Med there appear to be only two original research articles (plus a chapter in a thesis) on the topic of gluten in breast milk.
- Chirdo et al. Presence of high levels of non-degraded gliadin in breast milk from healthy mothers. Scand J Gastroenterol. 1998;33:1186-1192. Available at: http://www.ncbi.nlm.nih.gov/pubmed/9867098
- Troncone et al. Passage of gliadin into human breast milk. Acta Paediatr Scand. 1987;76:453-456. Available at: http://www.ncbi.nlm.nih.gov/pubmed/3300148
- Hopman et al. Presence of gluten protein in breast milk: implications for the development of celiac disease In Gluten intake and gluten-free diet in the Netherlands. 2008 (thesis). Available at: http://tinyurl.com/836j4a2 Note: this research was never submitted to a peer-reviewed journal for publication.
Research findings: For the first two cited articles, I have read only the abstracts. While I do not believe in commenting on articles I have not read in full, it is important to point out that despite the title of the first article (i.e., “Presence of high levels of non-degraded gliadin in breast milk…”), the mean amount of gliadin found in the human breast milk samples was 178 ng/ml which is 178 parts per billion or 0.178 parts per million. In my opinion this is NOT a large amount of gliadin. In the second cited article, gliadin was found in breast milk in amounts ranging from 5 to 95 ng/ml or 5 to 95 parts per billion or .005 to .095 ppm.
In the Hopman thesis, researchers used a competitive assay (used to assess gluten fragments) to determine the amount of various gliadin and glutenin peptides, including an epitope that is part of the celiac toxic 33-mer. As with the two other studies cited, peptides were found in breast milk in exceedingly small amounts measured in ng/ml (parts per billion). The mean levels of the three gliadin peptides were 0.132 parts per million; 0.129 parts per million; and 0.404 parts per million. The mean level of glutenin peptide was 0.045 parts per million.
In other words, human breast milk may contain exceedingly small amounts of gluten peptides.
Note: For those of you concerned about the implications of breast feeding on the development of celiac disease, this is the concluding statement from Hopman, “In the present study we show that low amounts of T cell stimulatory epitopes of gluten, both from gliadin and glutenin, are present in breast milk of mothers on a normal diet. Since oral tolerance to food antigens is induced early in childhood, in the period infants are breast-fed, these peptides might be involved in the induction of gluten tolerance.”
In other words, the tiny fragments of gluten that may be found in human breast milk may serve a protective role in preventing celiac disease.
It is very important to point out that the gluten peptide content of human breast milk has been studied very little. One of the above mentioned studies used a sandwich assay to detect peptide fragments. The other study and the thesis used competitive assays. The sandwich assay is not ideal for detecting peptide fragments. The competitive assays used in these publications have NOT been formally validated (defined as having undergone a multi-laboratory performance evaluation with results published in the peer-reviewed scientific literature). As a result, more research is needed in this area before any definitive statements can be made about the gluten peptide content of breast milk.
Research articles on gluten in cow’s milk: Based on a review of Pub Med, only one study has been conducted on the gluten peptide content of cow’s milk (Dekking et al. Intolerance of celiac disease patients to bovine milk is not due to the presence of T-cell stimulatory epitopes of gluten. Nutrition. 2009;25;122-123). Researchers fed dairy cows increasing amounts of wheat. They then tested milk samples for gluten and gluten derived peptides at levels down to detection limits of 1 to 3 ppm gluten. The study authors concluded that “no gluten or gluten fragments could be detected above background in any of the bovine milk samples.”
The competitive assay used in this study has not been formally validated. The sandwich assay (i.e., R5 ELISA) used in this study has been formally validated.
Conclusion: Please continue to enjoy your milk!
I would like to thank the cereal chemists and researchers consulted for this article.
© 2012 by Tricia Thompson, MS, RD. All rights reserved. This article may not be reprinted, reposted, or republished without the express written permission of Tricia Thompson