HUMAN HEATH BENEFIT OF A2 MILK  : PRODUCTION PRACTICES  OF A2 MILK FROM ZEBU CATTLE

HUMAN HEATH BENEFIT OF A2 MILK  : PRODUCTION PRACTICES  OF A2 MILK FROM ZEBU CATTLE

Milk is a liquid secreted from the mammary glands of female mammals following birth for the purpose of feeding the offspring. Since it is secreted with the purpose of feeding it – which after the birth is incapable of consuming any other type of food- the milk contains almost all the nutritional elements required to nourish the offspring. The milk, therefore, is a rare type of food which has the potential to contain all the nutrients necessary for life, and which the newborn offspring can consume easily (Fox et al, 2015). Although the amount of milk is very limited in humans and is secreted only in sufficient quantities for the baby, in animals it is usually secreted in higher amounts than needed by the offspring. This makes it possible to use some of the animal milk for the feeding purposes of the humankind. Furthermore, genetic studies have made certain animals capable of yielding significantly higher amounts of milk than they normally do (Patton, 2017). While milk shows differences in composition based on the mammal species it is secreted from, its primary components are always proteins, fats, and carbohydrates. The ratio of these components changes based on the needs of the offspring of the specific mammal species it was secreted for. Milk further contains other minor components like minerals, vitamins, and enzymes. When naming it, milk is called by the name of the animal it was secreted from (Fox et al, 2017). Milk proteins, milk fat, and lactose -which is the only carbohydrate in the milk- all hold a significant place in terms of nutrition and of the health of the consumer, and for the technological processing of the milk. Milk proteins are divided into two main parts as casein and serum proteins. A significant proportion of milk proteins are made up of caseins. Milks with casein that makes up for more than 2/3 of its total proteins are called the “casein milks”, whereas milks that contain other serum proteins in similar amounts with the casein are called the “albumin milks”. Milks of cows, sheep, goat, and buffalo are casein milks, while human, mare, donkey milks are albumin milks. Milks sold in markets and the majority of the dairy products that have technologically been processed are obtained from casein milks. Neither casein nor other serum proteins are of a single type of protein structure. Serum proteins are albumin, globulin, and protease-peptones. Casein, is composed of αs-casein, β-casein, κ-casein and γcasein fractions .

Milk is said to be nature’s perfect diet. But to Indians, Milk goes beyond dietary and nutritional outlook. The association of milk with the Indians remains to be connected not just in terms of economic backgrounds but also intertwines with the socio-cultural aspects. It’s very hard to find a home in India that does start their day without it. Milk wasn’t the same after Kurien came (Anonymous). Pioneer behind transforming our statistics from stage of “Cup of Tea” to the largest producer in the world. India is a land of milk puddles with the production reaching 198.4 million tonnes  in the year 2019-2020 and per capita, availability being 406 gm/day (DAHD and F, GoI).

Milk from a variety of livestock species and cow in particular has been included in the diet for infants, children and adults worldwide since it is the most common source of animal proteins and microelements known to be essential for human nutrition. Worldwide, the different sources of milk are cow, buffalo, goat, sheep and camel contributing 85%, 11%, 2%, 1.4% and 0.2% respectively to the total world milk production.

Apart from its emotional relationship, milk remains to play an important role in human nutrition and development throughout life. Milk is complex food containing different types of nutrients which help to meet the requirement of body protein, fat, sugar, minerals, and vitamins. In the present scenario, dairy cows are the major source of milk in the world. Milk from other animals is also consumed but the major contribution is from cows. Milk consumption brings in a controversial debate between its benefits and hazards. According to ancient ayurvedic literature cow milk is considered to possess medicinal properties along with its healthy nutritive value with bio-protective action and tissue regeneration effect [6]. While western studies say consumption of milk causes gastrointestinal disorders, digestive discomfort, and bloat with an increased risk of metabolic disorders. This controversy continues to remain with many turning to alternative diets i.e., veganism. What actually holds well is still unclear. Milk is an abundant source of proteins and biologically active peptides. Milk mainly contains two types of proteins namely, casein and whey protein. Casein making up 80% of total protein content is the largest group of milk proteins and is responsible for the white colour of milk. This casein protein is subdivided into αs1-, αs2-, β-, and κ-casein families. Among these families, beta-casein is the 2nd most abundant protein. Mutation in the beta-casein in cow milk led to the formation of 13 different genetic variants of beta-casein and among them, A1 and A2 beta-casein are the most common. Based on the type of casein protein, milk is named A1 and A2 milk. Several studies are suggesting that A2 milk is safer than A1 milk. Cow milk that contains A1 type β- casein, is considered A1 milk, and A2 type β- casein then it is called A2 milk.

A1 and A2 milk

Milk proteins are heterogeneous polymorphic compounds having different molecular structures and properties. Milk proteins include caseins, whey proteins, enzymes, minor proteins, and other non-protein nitrogen compounds. Casein proteins form the majority portion (80%) of the milk protein. There are different forms of caseins present in the milk among them β- caseins are the primary and 2nd most prevalent form that exists in 13 different forms. Among these subtypes, A1 and A2 β- caseins are the most common and considered important. Based on existing literature the type of caseins that a cow produces in its milk depends on the kind of genes it carries for the same. This expression can be homozygous for either A1 or A2 or it can exist together as heterozygous co-dominance. Hence the animal-producing milk that contains A1 β- casein is called A1 milk and A2 β- casein is called A2 milk. Originally, all milk was A2, but due to genetic mutation in the A2 beta-casein gene at some point about 3000 years ago in Europe, the A1 form appeared . Several studies and literature suggest that A1 milk is a potential etiological factor for human diseases such as type-I diabetes, coronary heart disease, autism, sudden infant death, and GI discomfort.

Does β- casein demarcation present only in cow’s milk? A1 milk has been exclusively found in the cattle of European origin. Not only milk contain A1 β- casein but also dairy products like yogurt, and cheese are likely to produce this A1 β- casein. Heat processing methods used in yogurt and cheese preparation also result in the release of BCM-7 . Unlike bovine milk, human milk contains exclusively proline making it an A2 type . Casomorphins released upon digestion of human milk differ from that BCM-7 in its amino acid sequence . On the other hand, milk from the less popular dairy animals such as sheep and goats were also found to be of the A2 type . Casein allergies associated with A1 milk are negligible with the dairy products made from the A2 milk.

What makes A1 and A2 β- caseins differ

Presence of histidine in A1 β- casein makes it susceptible to proteolytic degradation by enzymes of GIT. The matter of concern is when this peptide bond is digested by the enzymes like pepsin, aminopeptidase, and elastase, it leads to the formation of seven amino acid opioids like an intermediary digested product named β- casomorphin-7 (BCM-7). This active BCM-7 is found to pass through the intestinal barrier and is responsible for all the adverse effects of A1 milk consumption. While A2 milk is resistant to such digestion.

Cow breeds concerned with A1 and A2 milk

As discussed earlier due to genetic mutation at the 67th position, changes in the amino acids from proline (A2) to histidine (A1) lead to the most prevalent form of β- casein. The percentage of A1 and A2 β- casein production in the milch animals differ greatly among species, breeds, and at different geographical locations. This variation witnessed is more area-specific than breed-specific. Thus, the modern-day dairy breeds produce either A1 or A2, when both A1 and A2 are expressed, then the percentage varies between the breeds. Milk of northern European breeds contains a high amount of A1β- casein (A1 milk). A1 milk-producing breeds include Holstein, Friesians, Ayrshire, and British shorthorn. A2 milk-producing breeds are located in the Channel Islands and southern France such as Jersey, Guernsey, Charolais, and Limousine cows and also the zebu cattle of Asia and Africa. To increase milk production in India extensive cross-breeding has been encouraged which resulted in an increase in the Holstein and jersey population in our national herd. Both of which produce a varied amount of A1 and A2 milk across the world, but comparatively Jersey was found to produce A2 type milk. As per the 20th Livestock census, 73.5% of cattle are indigenous with 41 recognized breeds distributed in different agro-climatic regions of India. However, Screening of milch animals was done in a few breeds i.e., Buffaloes, Sahiwal, Tharparkar, Karan Fries, Karan Swiss. All were found to be of A2 type. Among different indigenous breeds, the Badri breed of the cow was found to have the highest percentage of A2 β- casein almost 90% [13]. Screening of animals for a type of milk protein has to be done using DNA analysis, many countries have their commercial kits available today.

Health concerns associated with A1 and A2 milk

Proteins present in bovine milk are a common source of bioactive peptides. Components in the milk show various constructive actions but some studies found that its metabolites show a severe threat to human health. BCM-7 is one such bioactive peptide that is released when A1 β- casein is digested in the gastrointestinal tract by the proteolytic enzymes however proline in A2 β- casein minimizes such proteolysis . BCM-7 possesses a deleterious effect on human health through its action on opioid receptors located in neural, immune, and endocrine systems . Many epidemiological observational suggest that consumption of A1 β- casein is associated with higher mortality rates from ischemic heart disease, cardiovascular diseases, type 1 diabetes, and even neurological disorders such as autism and schizophrenia.

Type 1 Diabetes (DM-1)

It is a common chronic autoimmune disease up surging globally at the rate of 3% per annum . This condition is developed mainly due to a lack of insulin resulting in insulin-secreting β cells destruction in the islets of Langerhans of the pancreas by some autoimmune processes. Though genetic susceptibility is the underlying cause environmental factors play potentiating effect on the phenotypic manifestation of DM-1 . The contribution of A1 cow milk to the development of DM-1 has been controversial for decades. The hypothesis behind the controversy is that A1 betacasein may increase the risk of DM-1 in genetically susceptible children with the release of opioid peptide, BCM-7, which affects the immune system and produces autoantibodies against β-cells of the pancreas. Also, BCM-7 through epigenetic modulation found to be differentially methylated genes that predispose DM-1 . In a case-control study in Finland, the early introduction of bovine milk resulted in an increased risk of DM-1 by 2 times . Many animal studies on rats and mice concluded the diabetogenic effect of milk protein and A1 β casein along with its mediating action via opioid receptors while such effect was negligible when A2 β casein was fed . However, the release of BCM-7 has not yet been demonstrated in human subjects. To comprehend, the onset of DM-1 is multifactorial, there exists numerous evidence pointing that A1 β casein could be a prime environmental trigger and casual factor potentiating its development .

 Coronary heart disease (CHD)

Coronary heart disease or ischemic heart disease is one of the major cardiovascular diseases. Foam cells play a crucial mediative role in the pathogenesis of atherosclerosis. These cells are formed as a result of fat infiltration in macrophages . Several studies reported the incidence of cardiovascular disease with the consumption of A1 beta-casein. McLachlan  suggested that more intake of A1 beta-casein could pose a risk of developing CHD and he also proved it with epidemiological evidence showing the association between A1 beta-casein and CHD in 30-69 years old age group males across 16 countries. He also postulated that BCM-7 is a possible etiological factor for cardiovascular disease. The possible hypothetical reason behind the effect of milk protein on CHD is the plasma cholesterol rising effect of casein. Tyrosyl is a protein oxidation product seen in atherosclerotic lesions, and BCM-7 is a possible source  that is believed to be involved in process of oxidation of low-density lipoproteins. Oxidized LDL is further engulfed by macrophages leading to the initiation of atherosclerosis. On the contrary, research including 15 asymptomatic adults (6Male and 9Female) who are at high risk of developing cardiovascular disease found that supplementing A1 milk had no adverse effect on cardiovascular health when compared to the A2 milk consumption. Similarly, Venn., et al.  showed that consumption of A1/A2 beta-casein did not affect plasma cholesterol concentration in humans. On the other hand, rabbits fed with A1 milk had higher cholesterol levels and showed a greater percentage of the aorta surface area covered by fatty streaks than A2 milk-fed rabbits . Though there is no direct practical evidence to prove this adverse effect of milk protein on cardiovascular health the correlation studies displayed a value of 0.79- 0.81 with coronary heart disease.

 Sudden infant death syndrome (SIDS)

According to Brooks , the death of infants between the first month to the first year of life is sudden infant death syndrome (SIDS). Respiratory infections, brain anomalies, environmental factors, and low birth weight which causes difficulty in breathing in a baby are some of the potential causes of infant death. Some researchers suggested that BCM-7 is also one of the potential causes of SIDS . It is believed that BCM-7, gets absorbed into the blood through the immature juvenile GI tract and can cross the blood-brain barrier due to the immature central nervous system in infants. Then it induces depression of the respiratory center in the brain stem causing the death of the infants with abnormal respiratory control and vagal nerve development. In support of this hypothesis, Wasilewska., et al. observed a higher level of BCM-7 in the sera of infants after an apnoea than the healthy infants of the same age. There is no strong practical evidence for this hypothesis and further investigations are needed to prove this association between the opioid-derived milk protein and SIDS.

Neurological disorders (Autism and Schizophrenia)

It has been reported that consumption of bovine milk containing A1 beta-casein is associated with neurological disorders such as autism and schizophrenia . Autism is a neurological disorder characterized by social deficit and repetitive behaviours, whereas schizophrenia is a mental disorder that affects a person’s ability to think, feel and behave clearly. Some studies are reporting that milk casein-derived peptide, BCM-7 might play role in the development of autism and schizophrenia. Some researchers are reported that milk peptides can show toxic effects at the level of the central nervous system by interacting with the neurotransmitters. According to a hypothesis, at an early age, genetic deposition and environmental stress cause changes in intestinal mucosa and increases the permeability of intestinal mucosa, and also cause a decrease in proteolytic activity. Reduced proteolytic activity and increased blood-brain barrier permeability lead to the accumulation of opioid peptides like BCM-7 in the brain and also in blood, which in turn results in hyperpeptidemia. An increased number of opioid peptides may affect the neurotransmitter systems in the brain and can cause disorders like autism and schizophrenia [28]. When such patients were fed a diet completely off gluten and casein, symptoms were got to reduced but the same did not completely cure the disorders . Kost., et al.  observed delayed motor and muscular development in babies fed with a diet containing cow milk than in those fed with breastfeeding.

Gastrointestinal discomfort

There is an increasing trend of people exhibiting milk intolerance syndrome upon consumption of milk and dairy products. This could be attributed to the following reasons firstly, inability to digest lactose, falling under the lactose intolerant category, and secondly, A1 protein intolerance. Thirdly BCM-7 released from A1 β casein is known to slow down food passage that provides a longer time for lactose fermentation [40]. Many researchers have also reported that increased consumption of bovine milk (especially A1 milk) is related to an increased incidence of gastrointestinal disorders. BCM-7, a milk-derived bioactive peptide is thought to be a potential cause of gastrointestinal tract-associated disorders in humans consuming dairy products. This bioactive peptide is known to activate µ-receptors of the GIT and alter GI motility in adults and neonates . A1 β casein has been known to trigger a local inflammatory reaction which was evident by the release of pro-inflammatory markers such as myeloperoxidase in the laboratory animals, as such results though not replicated in the humans, subclinical inflammatory response to the A1 β casein cannot be ruled out. BCM-7 disrupts gastrointestinal function and disturbs the niche of commensal bacteria through mucus production . Clinical trials in humans revealed a strong correlation in the study group who consumed A1 milk exhibited gut inflammation, abdominal pain, and higher bloating.

What makes A2 milk healthy

Dairy products are revered and chosen considering their calcium content. Calcium is the major inorganic element in the animal kingdom and is known to reduce the risk of colon cancer and prevent osteoporosis . The calcium to magnesium ratio of milk does alter its beneficial effects. A high Ca to Mg ratio increases the risk of colorectal cancer along with multiple chronic conditions such as cardiovascular disease, calcification, osteoporosis, and bone fractures . The ideal calcium to magnesium ratio suggested would range from 1.70 to 2.60. The same of A1 milk is 10:1, which is far higher than that of A2 milk i.e., 2:1. Thus indirectly in dicating the health benefits of A2 milk. . In few clinical studies conducted on humans proved, that no subjects witnessed neither classical digestive disturbances such as abdominal pain, bloat, and inflammation , nor signs of milk allergies . To some extent to a few reports, it is now clear that the adverse effects caused by A1 milk are not replicated with the consumption of A2 milk. In the light of Vedic literature, Indian cow milk has got huge importance in terms of its unique beneficial effects. This area is less explored by the scientific community. Cow’s milk is believed to possess anti-aging properties, antifungal properties  anti-cancer properties with a tonic effect on the heart and brain. Such effects are more pronounced in value-added products such as curd, ghee, buttermilk, etc. That is the reason why milk and milk products have always been part of a conventional traditional Indian family. Though huge oral evidence is present on the exceptional benefits of A2 milk, scientific evidence has to be supplemented to make it established globally.

Production Practices of A2 Milk from Zebu Cattle

A2 milk, derived from the milk of certain cattle breeds, particularly Zebu or Bos indicus cattle, has gained popularity in recent years due to its perceived health benefits. A2 milk contains a specific type of beta-casein protein called A2 beta-casein, which is believed to be easier to digest for some individuals compared to the A1 beta-casein protein found in the milk of Holstein and other dairy breeds. Producing A2 milk from Zebu cattle involves specific practices to ensure milk quality and breed management. Here are the key production practices for A2 milk from Zebu cattle:

1. Selecting Zebu Cattle:

• Choose Zebu cattle breeds or crossbreeds that carry the A2 beta-casein gene. Examples include Gir, Sahiwal, Tharparkar, and Red Sindhi.

2. Genetic Testing:

• Conduct genetic testing to confirm the presence of the A2 beta-casein gene in your cattle herd. This is essential to identify A2 milk producers.

3. Breeding and Herd Management:

• Implement selective breeding practices to increase the proportion of A2 beta-casein carriers in your herd. Over time, this will result in a higher percentage of A2 milk production.
• Maintain proper herd health and nutrition to ensure the well-being of your Zebu cattle. A healthy and well-fed herd will produce better-quality milk.

4. Milking Practices:

• Implement rigorous milking hygiene practices to maintain the quality and safety of the milk.
• Ensure that milking equipment is properly cleaned and sanitized to prevent contamination.

5. Milk Handling and Storage:

• After milking, handle and store A2 milk in clean, stainless steel containers to prevent any contamination.
• Keep the milk chilled immediately after milking to maintain its freshness.

6. Quality Control:

• Regularly test the milk to confirm its A2 beta-casein content and overall quality.
• Conduct microbial testing to ensure that the milk meets safety standards.

7. Marketing and Labeling:

• Clearly label the milk as “A2 milk” to differentiate it from regular milk and inform consumers of its unique qualities.
• Develop a marketing strategy that highlights the health benefits associated with A2 milk.

8. Consumer Education:

• Educate consumers about the differences between A2 and A1 milk and the potential benefits of A2 milk for those who may have difficulty digesting A1 milk.

9. Regulatory Compliance:

• Ensure compliance with local regulations and labeling requirements for A2 milk.

10. Environmental Considerations:

• Implement sustainable and environmentally responsible practices to reduce the ecological footprint of your dairy farm.

11. Record Keeping:

• Maintain records of genetic testing, milking data, and quality control measures to track and improve A2 milk production.

It’s important to note that while A2 milk is believed to be easier to digest for some individuals, scientific research on its health benefits is ongoing. The success of A2 milk production from Zebu cattle relies on diligent breeding and management practices to ensure milk quality and genetic purity. Additionally, consumer education and marketing are crucial for informing the public about the unique qualities of A2 milk and its potential advantages.

HUMAN HEATH BENEFIT OF A2 MILK

A2 milk, derived from the milk of certain cattle breeds that produce A2 beta-casein protein, has gained attention due to its perceived health benefits compared to conventional milk containing A1 beta-casein protein. While more research is needed to fully understand the potential health advantages of A2 milk, several potential benefits have been suggested:

1. Easier Digestibility:

• One of the primary reasons individuals choose A2 milk is its perceived ease of digestibility. Some people who experience digestive discomfort, such as bloating or gas, after consuming conventional A1 milk report fewer or milder symptoms when drinking A2 milk.

2. Reduced Gastrointestinal Discomfort:

• A2 milk is believed to cause less gastrointestinal distress in some people, particularly those with lactose intolerance or non-specific milk-related discomfort. This may be due to differences in how A2 beta-casein is digested and metabolized.

3. Potential for Reduced Inflammation:

• Some studies have suggested that A2 milk may be associated with lower levels of inflammation in the body compared to A1 milk. Reduced inflammation is often linked to improved overall health.

4. Potential for Allergy Alleviation:

• There is some speculation that A2 milk may be less likely to trigger milk allergies in susceptible individuals. However, this area requires further research to establish definitive conclusions.

5. Better Tolerance in Autism Spectrum Disorder:

• A limited amount of research has explored the link between A2 milk and autism spectrum disorder. Some preliminary findings suggest that A2 milk may be better tolerated by some individuals with autism, leading to reduced behavioral issues.

6. Enhanced Nutrient Absorption:

• Improved nutrient absorption, particularly with regard to essential minerals like calcium, may be a potential benefit of A2 milk. It is suggested that the reduced gastrointestinal distress associated with A2 milk could lead to better overall nutrient absorption.

7. A2 Milk for Infant Nutrition:

• There is interest in using A2 milk in infant formulas, as some believe it may be better tolerated by babies who are sensitive to A1 milk. However, it’s important to note that this area requires thorough research and regulation.

It’s essential to emphasize that while these potential benefits of A2 milk have been suggested, more research is needed to provide conclusive evidence of its advantages. Not everyone experiences the same level of improvement in digestibility or health when switching to A2 milk. Furthermore, individual responses to milk can vary, and some people may not notice any significant difference when they switch from A1 to A2 milk.

If you are considering switching to A2 milk due to specific health concerns or intolerances, it is advisable to consult with a healthcare professional for guidance. Additionally, always check the labeling and sourcing of A2 milk to ensure that it is a legitimate product that meets safety and quality standards.

Conclusion

To conclude India has been gifted with unique cattle breeds that are so evolved and adapted, by mere mimicking western ideology considering economic benefits, much of our true gene pool was diluted and germplasm has been on verge of vanish. A lot of scopes still exist for its conservation and propagation. Interdisciplinary research involving universities, industries, and farmers considering our environmental conditions to find the true potential and worth of our resources will certainly yield some beneficial information. Strict implementation of breeding policies must be considered which otherwise leads to irreplaceable losses that humankind would never bring back.

Compiled  & Shared by- This paper is a compilation of groupwork provided by the

Team, LITD (Livestock Institute of Training & Development)

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 Reference-On Request.

A2 milk: A healthier choice