A2 Milk: Definition, Health, and Profitability

A2 milk comes from cows that only produce the A2 variant of the β-casein protein, while conventional milk typically contains both A1 and A2. β-casein A1 and A2 differ by a single amino acid at position 67: A1 has histidine (His) and A2 has proline (Pro) (1). This mutation (which occurred some 4,000–5,000 years ago) allows β-casein A1 to release a peptide called β-casomorphin-7 (BCM-7) during digestion (2), a plant opioid with a possible inflammatory effect. In contrast, the digestion of β-casein A2 does not produce BCM-7, but rather a different peptide (β-casomorphin-9) with antioxidant properties (2). In summary:

• Genetics and structure: A1 has His^67; A2 has Pro^67 (1).

• Digestion: A1 releases BCM-7 (a 7-amino acid opioid) when hydrolyzed (2), while A2 does not produce BCM-7.

• Historical context: Originally, all cows produced A2 (like human milk), and the A1 variant appeared due to a mutation during domestication (3).

Digestibility and Gastrointestinal Symptoms

It has been suggested that A2 milk may be more digestible or cause less intestinal discomfort in sensitive individuals. Clinical studies partially support this idea: for example, a double-blind trial in 41 adults found that milk with β-casein A1 increased stool hardness and intestinal inflammation (calprotectin) compared to A2 milk (4). In that study, abdominal pain correlated with fecal consistency in the A1 group, but not in the A2 group (4). Similar trials have shown that consumers with subjective milk intolerance report less abdominal pain, fecal urgency, and other digestive discomforts when consuming A2 milk instead of conventional (A1/A2 mixed) milk (4, 5). In preschool-aged children with poor milk tolerance, replacing regular milk with A2 milk significantly reduced the severity of gastrointestinal symptoms (abdominal pain, frequency, and consistency of bowel movements) (5).

Systematic reviews based on these clinical studies summarize that there is indeed a tendency for more digestive discomfort with β-casein A1 in sensitive individuals (4, 5). It has also been observed that A1 milk can delay intestinal transit and increase inflammatory markers in some subjects (4, 6). However, the evidence is not uniform and depends on the type of consumer. For example, the European Food Safety Authority (EFSA) concluded that there is no demonstrated cause-and-effect relationship between the consumption of BCM-7 (or A1 milk) and chronic human diseases such as type 1 diabetes or cardiovascular disease (7, 8). However, it is recognized that in special populations (infants, people with increased intestinal permeability), BCM-7 could be detected in the blood and associated with symptoms (8, 9). In short, the amount of lactose is the same in both milks, but β-casein A1 may worsen gastrointestinal symptoms in sensitive individuals beyond lactose intolerance (10, 11).

Nutritional Composition and Technological Properties

Nutritionally, conventional A2 and A1 milks are very similar. Comparative studies find that the overall macronutrient composition (total proteins, fat, carbohydrates, minerals) barely differs between genotypes (12). Small differences have been reported: for example, A2 milk may have slightly more total protein and fat than A1, as well as a slightly different amino acid profile (more leucine) (13). Changes do appear in dairy technology: β-casein A2 influences coagulation and gelling. Some research indicates that A2 milk forms weaker curds and slower gels when coagulated with rennet, and that it has a higher emulsifying capacity but a poorer foaming capacity than A1 (14, 15). In cheesemaking, A2 milk generally results in lower cheese firmness compared to A1 milk (16, 17). However, the sensory differences (taste, smell, texture) are minimal: the public barely notices changes in color or flavor (18).

Scientific Evidence and Official Positions

The scientific literature contains positive, negative, and neutral reviews of A2 milk. Controlled trials have found that consuming A2 milk instead of conventional milk reduces some symptoms of poor milk tolerance (4, 5). However, other research and official evaluations warn that the evidence is still limited. For example, the US Dairy Board states that "the science is limited" and that, so far, the detected gastrointestinal differences have been minor (changes in stool consistency) and inconclusive (19). The EFSA (2009) conducted a comprehensive review of the literature and concluded that there is no solid evidence that the ingestion of BCM-7 via A1 milk causes human diseases such as diabetes or autism (7, 8). In parallel, several recent meta-analyses (2017–2021) confirm that β-casein A1 can delay intestinal transit but have not found a clear link with cardiovascular or endocrine risks (6). Consequently, regulatory bodies and reviewers have not issued specific health warnings about A1/A2 milk; in fact, they agree that from a nutritional standpoint, both milks are equivalent and provide the same basic nutrients (7, 20).

Dairy Production and Economic Aspects

The production of A2 milk requires genetic selection and a dedicated supply chain. Many conventional dairy breeds (Holstein, Ayrshire, Jersey, etc.) carry both A1 and A2 alleles. For example, in European breeds, the Guernsey has ~92% A2 cows, while Holstein or Ayrshire have ≈60% A1 (21). To guarantee 100% A2 milk, dairy farmers must genotype their cows (using a DNA test) and separate the production from milking onward: milking A2 cows separately, using independent tanks, and isolated transportation and processing (22, 23).

• Breeding and genetics: Breeders can choose breeds or lines with a high A2 frequency, or use A2/A2 sires. Current genetic tests are increasingly affordable (22).

• Infrastructure: Milking separately increases operational costs. It is crucial to maintain traceability because mixing in a little A1 milk "contaminates" the premium product. In Galicia (Spain), the A2 chain is certified with independent milking and transport (23).

• Price and profitability: A2 milk is usually sold at a price premium. For example, The A2 Milk Company pays its producers 5–7% more (24). Market studies indicate that European consumers are willing to pay about €0.20–€0.30 more per liter of A2 milk than for conventional milk (25) (although in other regions the willingness to pay extra is lower). The Galician project Leite Noso signed long-term contracts for its farmers precisely because of this price differential and the stability it offers (26).

• Opportunities: Becoming an A2 milk supplier opens access to high-demand market niches (sensitive or high-income individuals). Some farmers consider it "a small revolution" to add value to the national product (26).

• Challenges: It is necessary to scientifically demonstrate the benefits to justify the investment. There is also a risk of fraud: there have already been reports of milk labeled as A2 being mixed with common milk (27), which requires rigorous controls and certifications.

In short, A2 dairy farming involves an initial investment (genetic tests, separate logistics) and a largely premium market, but it offers improved contracts and product differentiation. Its economic viability depends on local demand and compliance with quality standards.

Global Market and Consumer Trends

Global interest in A2 milk has grown over the last two decades. New Zealand was the pioneer: in 2003, The A2 Milk Company was launched, and A2 milk quickly captured ~10% of the dairy market in Australia (28). Since then, A2 production has expanded to the United States, China, India, Europe, and other markets (28, 29). Key players include:

• Oceania and the U.S.: The A2 Milk Company (NZ/Australia) leads the sector; local brands in the U.S. (e.g., Westfarms or Costco supermarkets) also offer A2 milk.

• Asia: In India, the GCMMF cooperative (Amul brand) sells milk from selected desi cows (native heifers) as A2 under the name Amul Deshi A2 (30). China imports A2 milk and is developing A2 breed farming.

• Europe: Emerging projects (e.g., Spain with “Deleite” (23), France and the United Kingdom with artisan launches). Arla Foods has introduced A2 milk in Northern Europe (e.g., “Arla® A2”) and will launch infant formulas with A2 casein (29).

• Latin America: Dairy companies in Brazil and India are showing interest; the regional market is still nascent but with ongoing research and partnerships.

Market studies reflect strong demand growth. The global A2 milk market is projected to reach approximately USD 6.93 billion in 2029 (a CAGR of ~21.7%) (31). In Europe, it is estimated to be worth ~$635.5 million in 2024, with a compound annual growth rate of ~18% (32). These forecasts respond to the trend of consumers seeking "easy to digest" foods or those with potential health benefits (33, 34). Furthermore, the commercial offering is diversifying (liquid, powdered milks, yogurts, and A2 cheeses), and clear labeling is also growing: many brands highlight "only A2 casein" or specific logos on the packaging.

Conclusions

A2 milk is not a magic product, but it offers potential advantages in certain cases. In summary:

• Clinical studies show relief of gastrointestinal symptoms (pain, bloating, frequency of bowel movements) in people with subjective intolerance when consuming only A2 milk instead of A1/A2 milk (4, 5).

• However, there is no conclusive evidence that A2 milk prevents chronic diseases (diabetes, cardiovascular, autism) beyond what normal milk provides (7, 8). Organizations like the EFSA have stated that, so far, β-casomorphin-7 derived from A1 does not cause measurable harmful effects in healthy adults (7, 8).

• Nutritionally, both milks are equivalent: they provide the same essential macro/micronutrients. The protein and technological differences are very minor (e.g., cheese consistency) (12, 35).

• Digestive health: Lactose is the same in A1 and A2, but studies indicate that A2 may reduce discomfort in sensitive consumers, beyond the effects of lactose (5, 10).

• Economically: A2 milk can improve a farmer's profitability through premium prices and stable contracts (24, 26). However, it requires investment in differentiated management and a certified chain.

• Commercial viability: The A2 market is growing rapidly in several countries, but for now, it is a niche market. Its future success will depend on further evidence of benefits and maintaining consumer trust (by avoiding fraud) (26, 27).

In conclusion, A2 milk can offer a valuable option for consumers who experience discomfort with regular milk, and it represents a commercial differentiation opportunity. However, its supposed universal health benefits have not yet been fully demonstrated, so it is recommended to interpret the information with discretion and follow ongoing scientific studies (4, 7).

References: Scientific studies and reports cited in the text (1, 2, 4, 5, 7, 8, 12, 22, 23, 24, 26, 31, 32, 35) (See list of connected sources.).

(1, 12,13, 16, 17, 18, 21, 22, 24, 25, 27, 28, 34) A2 Milk: New Perspectives for Food Technology and Human Health

https://www.mdpi.com/2304-8158/11/16/2387

(2) ri-ng.uaq.mx

https://ri-ng.uaq.mx/bitstream/123456789/11179/1/CNMAC-317851.pdf

(3, 23, 26, 29) Ganaderos gallegos lanzan una marca de leche A2: “Es el futuro del sector” | Economía | EL PAÍS

https://elpais.com/economia/2021-08-27/ganaderos-gallegos-lanzan-una-marca-de-leche-a2-es-el-futuro-del-sector.html

(4) Comparative effects of A1 versus A2 beta-casein on gastrointestinal measures: a blinded randomised cross-over pilot study - PubMed https://pubmed.ncbi.nlm.nih.gov/24986816/

(5) Efectos de la leche convencional frente a la leche que contiene solo B-Caseína A2 en la digestión

https://www.puntalitospediatricos.com/post/efectos-de-la-leche-convencional-frente-a-la-que-contiene-solo-b-case%C3%ADna-a2-en-la-digesti%C3%B3n-de-ni%C3%B1os

(6, 7,14,15, 35) A2 milk consumption and its health benefits: an update - PMC

https://pmc.ncbi.nlm.nih.gov/articles/PMC10806982/

(8, 9, 10, 11) La verdad sobre la leche A1 y A2

https://www.eldiario.es/consumoclaro/tu-mejor-yo/verdad-leche-a1-a2_1_1131305.html

(19, 20) Understanding the Science Behind A2 Milk | U.S. Dairy

https://www.usdairy.com/news-articles/understanding-the-science-behind-a2-milk

(30, 31, 33) Se espera que el mercado de leche A2 aumente con una CAGR del 21,7 % para 2029

https://www.databridgemarketresearch.com/es/news/global-a2-milk-market?srsltid=AfmBOoqfRDjBLHtP0PzWIGXueOw3ah0HAwhoF5mq-RMHbH3ovrnsKoNw Europe A2

(32) Milk Market Size & Outlook, 2030

https://www.grandviewresearch.com/horizon/outlook/a2-milk-market/europe