A2 Milk
What is A2 Milk?
A2 milk may be a better milk option for those that want the benefits of milk without the inflammatory, gastrointestinal, and cognitive effects that can come from conventional milk. It may also be easier for those with dairy intolerance to digest.
Milk contains two major proteins: casein and whey. Approximately ⅓ of the proteins found in milk consist of a specific casein called β-casein (pronounced: beta cay-seen).
Depending on the type of cow, the form of β-casein can be A1 and/or A2. Goat and Sheep’s milk are naturally an A2 β-casein milk. [1]
Most African and Asian cattle produce only A2 β-casein, while cattle from Australia, New Zealand, and Europe produce both A1 and A2 β-casein.
Conventional milk contains both A1 and A2 β-casein, while A2 milk contains solely A2 β-casein.
A2 milk has gained popularity in recent years as A1 β-casein has been associated with negative cognitive, gastrointestinal, and inflammatory effects. Refer to the research section at the bottom of the page for more information about these effects.
This difference seen between A1 and A2 β-casein is due to a molecule that is only released during the digestion of the A1 β-casein. This molecule is called BCM-7. It belongs to a class of chemicals that are known to have addictive properties. This may explain the “addiction” that can be seen in some people who drink conventional milk. [2]
Dairy Sensitivity and A2 Milk
For more on the difference between an intolerance, sensitivity, and allergy, see the Food Reactions note.
An individual can be lactose intolerant and not allergic to the protein in milk or the lactose in milk. If an individual is intolerant, their body will not have an immune response, rather lacking the enzyme lactase that breaks down lactose. Milk intolerance requires different treatment from true milk allergy. In the case of an intolerance, the individual may tolerate A2 milk better than A1.
If an individual is has a dairy sensitivity, A2 milk may be better tolerated.
NOTE: For those that have a true dairy allergy, A2 milk would not be an appropriate beverage to consume as they will still have an immune response, and possibly dangerous allergic reaction. See ideas for better alternatives in the “A2 Milk Alternatives” section.
Although A2 milk may be a better option than conventional milk for those without a dairy allergy, this still may not be appropriate for kids with autism. For more on the dairy-free diet, click here.
Nutrient Breakdown
A2 milk is a great source of:
Potassium- an essential mineral important for bone and heart health. Adequate intake reduces your risk of coronary heart disease and stroke
Enrichment in A2 Milk
Some individuals with ASD are sensitive to added vitamins since they are often an inactive form. If this is a concern, unenriched dairy products are available (just read the labels).
Common vitamins enriched in dairy products include:
Foods Containing A2 Milk
A2 Milk Yogurt
A2 Milk Kefir
Sheep’s milk
Goat’s milk
Certain baby formulas are formulated exclusively with A2 milk
A2 Milk Alternatives
If your child doesn’t like A2 milk yet or they are sensitive to it, here are some alternatives that are similar in nutritional value!
Almond milk
Soy milk
Oat milk
Cashew milk
Coconut milk
Rice milk
Hemp milk
Food Reactions
The body can respond to foods in many different ways including food allergies, food sensitivities, or food intolerances. If you suspect a food reaction, you can either choose to avoid the food or seek food reaction testing. Click here more information on the difference in types of food reactions and testing options.
DISCLAIMER: Always consult with your pediatrician and/or your Registered Dietitian to help you test for a food reaction or to aid you in making individualized dietary changes.
A2 Milk & Autism in the Research
A2 Milk and Intolerance to Dairy Products
When comparing conventional milk containing both A1 and A2 β-casein versus milk containing solely A2 β-casein, researchers in one study found that “milk containing both β-casein types was associated with significantly greater PD3 symptoms [post-dairy digestive discomfort]; higher concentrations of inflammation-related biomarkers and β-casomorphin-7”. [3]
β-casomorphin-7 or BCM-7, is a peptide derived from the digestion of the A1 β-casein type, but not the A2 β-casein type.
Researchers hypothesize that although intolerance to dairy products is typically attributed to lactose intolerance, BCM-7’s inflammatory and gastrointestinal effects related to the consumption of A1 β-casein may be to blame for this intolerance rather than lactose. [3]
A2 Milk and Oxidative Stress
BCM-7 released from the digestion of A1 β-casein has been implicated in promoting oxidative stress. [4]
Researchers found that this oxidative stress is due to BCM-7’s ability to decrease the uptake of the amino acid cysteine, a sulfur amino acid necessary for the synthesis of the primary master endogenous antioxidant, glutathione. [5]. Not only this but it’s also been found to directly decrease cellular glutathione levels. [6] Glutathione is the primary antioxidant used in the body to help combat oxidative stress and subsequent inflammation.
Recent research shows that children diagnosed with ASD generally have 20-40% lower levels of the biologically active form of glutathione than children without ASD. [7] Read more about glutathione.
A2 Milk and Cognitive Function
In one study, researchers aimed to compare the effects of 5 days’ consumption of conventional milk containing both A1 and A2 β-casein versus milk containing only A2 β-casein on the cognitive behavior of healthy preschoolers with mild-to-moderate milk intolerance. [8]
Cognitive function was analyzed using a Subtle Cognitive Impairment Test. This is a brief computer-based, perceptual judgment task that is sensitive to small differences in global cognitive performance.
This test showed significant improvements in test accuracy after consumption of milk containing only A2 β-casein, suggesting improvements in cognitive function.
A2 Milk and Gut Health
Short-chain fatty acids are microbial fermentation by-products from our gut microbiota. They serve as an integral part of supporting gut health by enhancing colon cell function, having anti-inflammatory properties, and maintaining gut barrier integrity to reduce intestinal permeability, or “leaky gut”. [9]
Gastrointestinal problems are commonly documented in those with ASD. Alterations in the gut microbiome play a huge role in this as they are implicated in leaky gut, which allows metabolites of bacteria to cross the gut barrier and elicit neurodevelopment issues during childhood by way of the gut-brain axis. [10]
One study found that the consumption of milk containing both A1 and A2 β-casein was associated with significantly lower SCFA concentrations when compared to those consuming milk containing only A2 β-casein, suggesting that A1 β-casein consumption leads to reduced SCFA levels. [3]
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[1] Küllenberg de Gaudry, D., Lohner, S., Schmucker, C., Kapp, P., Motschall, E., Hörrlein, S., Röger, C., & Meerpohl, J. J. (2019). Milk A1 β-casein and health-related outcomes in humans: a systematic review. Nutrition reviews, 77(5), 278–306. https://doi.org/10.1093/nutrit/nuy063
[2] Kurek, M., Przybilla, B., Hermann, K., & Ring, J. (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. https://doi.org/10.1159/000236106
[3] Jianqin, S., Leiming, X., Lu, X., Yelland, G. W., Ni, J., & Clarke, A. J. (2016). Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cows' milk. Nutrition journal, 15, 35. https://doi.org/10.1186/s12937-016-0147-z
[4] Kay, S. S., Delgado, S., Mittal, J., Eshraghi, R. S., Mittal, R., & Eshraghi, A. A. (2021). Beneficial Effects of Milk Having A2 β-Casein Protein: Myth or Reality?. The Journal of nutrition, 151(5), 1061–1072. https://doi.org/10.1093/jn/nxaa454
[5] Trivedi, M. S., Shah, J. S., Al-Mughairy, S., Hodgson, N. W., Simms, B., Trooskens, G. A., Van Criekinge, W., & Deth, R. C. (2014). Food-derived opioid peptides inhibit cysteine uptake with redox and epigenetic consequences. The Journal of nutritional biochemistry, 25(10), 1011–1018. https://doi.org/10.1016/j.jnutbio.2014.05.004
[6] Deth, R., Clarke, A., Ni, J., & Trivedi, M. (2016). Clinical evaluation of glutathione concentrations after consumption of milk containing different subtypes of β-casein: results from a randomized, cross-over clinical trial. Nutrition journal, 15(1), 82. https://doi.org/10.1186/s12937-016-0201-x
[7] Kern, J. K., Geier, D. A., Adams, J. B., Garver, C. R., Audhya, T., & Geier, M. R. (2011). A clinical trial of glutathione supplementation in autism spectrum disorders. Medical science monitor : international medical journal of experimental and clinical research, 17(12), CR677–CR682. https://doi.org/10.12659/msm.882125
[8] Sheng, X., Li, Z., Ni, J., & Yelland, G. (2019). Effects of Conventional Milk Versus Milk Containing Only A2 β-Casein on Digestion in Chinese Children: A Randomized Study. Journal of pediatric gastroenterology and nutrition, 69(3), 375–382. https://doi.org/10.1097/MPG.0000000000002437
[9] Tan, J., McKenzie, C., Potamitis, M., Thorburn, A. N., Mackay, C. R., & Macia, L. (2014). The role of short-chain fatty acids in health and disease. Advances in immunology, 121, 91–119. https://doi.org/10.1016/B978-0-12-800100-4.00003-9
[10] Fowlie, G., Cohen, N., & Ming, X. (2018). The Perturbance of Microbiome and Gut-Brain Axis in Autism Spectrum Disorders. International journal of molecular sciences, 19(8), 2251. https://doi.org/10.3390/ijms19082251
Authors
Brittyn Coleman, MS, RDN/LD, CLT
Blayne Andrews, Dietetic Intern
