Dairy consumption worldwide is astoundingly high. It is estimated that between 94-99% of people regularly consume dairy products1 and up to 36% of people drink 2-3 glasses of milk a day2. Dairy is often recommended as highly nutritious and beneficial.
However, there is a negative side to dairy and it has been linked to several conditions. Lactose intolerance is known to give gastrointestinal symptoms such as bloating, gas, diarrhea and abdominal discomfort. These gastrointestinal issues are down to the lack of an enzyme that breaks down lactose, the milk sugar.
Protein in dairy may also pose problems and cows' milk allergy, delayed or immediate, may affect many children between the ages of one and five. Casein Sensitivity, often not involving IgE antibodies, is also more common than first thought.
Some dairy products, such as cheese, have higher levels of casein compared to milk. Casein may be in different forms in milk and beta-casein is the second most common form.
Beta-casein itself has many variants and among the most common are the A1 beta-casein and A2 beta-casein variants. The amount of each variant present depends on the breed of cow. Some cows such as Red, Holstein-Friesian and Ayrshire produce high levels of the A1 variant of beta-casein, whereas Guernsey and Jersey cattle produce the A2 variant of beta-casein3.
High levels of both these antibodies have been shown in cases of ASD, schizophrenia16 and dyslexia17. Casein has also been shown to influence the release of inflammatory cytokines18 (chemical messengers) in autism which can affect the gut lining19 and lead to further problems with food sensitivities.
References
http://www.dairyuk.org/industry-overview/consumption-sales Accessed 24.11.16
http://www.statisticbrain.com/milk-consumption-statistics/ Accessed 24.11.16
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Boutrou, R., Gaudichon, C., Dupont, D., Jardin, J., Airinei, G., Marsset-Baglieri, A., ... & Leonil, J. (2013). Sequential release of milk protein–derived bioactive peptides in the jejunum in healthy humans. The American journal of clinical nutrition, 97(6), 1314-1323.
Kurek, M., Przybilla, B., Hermann, K., & Ring, I. (1992). A naturally occurring opioid peptide from cow's milk, beta-casomorphine-7, is a direct histamine releaser in man. International archives of allergy and immunology, 97(2), 115-120.
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Elliott, R. B., Harris, D. P., Hill, J. P., Bibby, N. J., & Wasmuth, H. E. (1999). Type I (insulin-dependent) diabetes mellitus and cow milk: casein variant consumption. Diabetologia, 42(3), 292-296.
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McLachlan, C. N. S. (2001). β-Casein A 1, ischaemic heart disease mortality, and other illnesses. Medical Hypotheses, 56(2), 262-272.
Wasilewska, J., Sienkiewicz-Szłapka, E.,Kuźbida, E., Jarmołowska, B., Kaczmarski, M., & Kostyra, E. (2011). The exogenous opioid peptides and DPPIV serum activity in infants with apnoea expressed as apparent life threatening events (ALTE). Neuropeptides, 45(3), 189-195.
Sun, Z., Zhang, Z., Wang, X., Cade, R., Elmir, Z., & Fregly, M. (2003). Relation of β-casomorphin to apnea in sudden infant death syndrome. Peptides, 24(6), 937-943.
Lucarelli, S., Frediani, T., Zingoni, A. M., Ferruzzi, F., Giardini, O., Quintieri, F., ... & Cardi, E. (1995). Food allergy and infantile autism. Panminerva medica, 37(3), 137-141.
Kost, N. V., Sokolov, О. Y., Kurasova, О. B., Dmitriev, A. D., Tarakanova, J. N., Gabaeva, М. V., ... & Mikheeva, I. G. (2009). β-Casomorphins-7 in infants on different type of feeding and different levels of psychomotor development. Peptides, 30(10), 1854-1860.
Hidvegi, E., Cserhati, E., Kereki, E., Savilahti, E., & Arato, A. (2002). Serum immunoglobulin E, IgA, and IgG antibodies to different cow's milk proteins in children with cow's milk allergy: association with prognosis and clinical manifestations. Pediatric allergy and immunology, 13(4), 255-261.
Hochwallner, H., Schulmeister, U., Swoboda, I., Twaroch, T. E., Vogelsang, H., Kazemi‐Shirazi, L., ... & Fröschl, R. (2011). Patients suffering from non‐IgE‐mediated cow's milk protein intolerance cannot be diagnosed based on IgG subclass or IgA responses to milk allergens. Allergy, 66(9), 1201-1207.
Cade, R., Privette, M., Fregly, M., Rowland, N., Sun, Z., Zele, V., ... & Edelstein, C. (2000). Autism and schizophrenia: intestinal disorders. Nutritional Neuroscience, 3(1), 57-72.
Knivsberg, A. M. (1997). Urine patterns, peptide levels and IgA/IgG antibodies to food proteins in children with dyslexia. Pediatric rehabilitation, 1(1), 25-33.
Jyonouchi H, Sun S, Itokazu N. Innate immunity associated with inflammatory responses and cytokine production against common dietary proteins in patients with autism spectrum disorder. Neuropsychobiology 2002; 46: 76–84.
Heyman M, Desjeux JF. Cytokine-induced alteration of epithelial barrier to food antigens in disease. Ann NY Acad Sci 2000; 915: 304–11
https://www.greatplainslaboratory.com/glutencasein-peptides-test Accessed 24.11.16.
Montalto, G., Custro, N., Notarbartlo, A., Carroccio, A., Cavataio, F., D'amico, D., ... & Iacono, G. (2000). Evidence of very delayed clinical reactions to cow's milk in cow's milk‐intolerant patients. Allergy, 55(6), 574-579.