Dr. Deepikesh Joshi
PhD scholar
Deptt. of Livestock Production Management (LPM)
College of Veterinary and Animal Sciences
GBPUAT, Pantnagar (Uttarakhand)
&
Dr. D.V. Singh
Prof. and Head
Deptt. of Livestock Production Management (LPM)
College of Veterinary and Animal Sciences
GBPUAT, Pantnagar (Uttarakhand)
Milk is a highly evolved secretion of mammary glands of mammals and has always been an outstanding source of nutrients which is considered as an essential food for infants. It is a very good source of calcium and protein and acts as a complete diet except Iron and Vitamin C. Milk has about 86% water, 4.6% lactose sugar, 3.7% triglycerides, 2.8% milk protein, 0.54% minerals and 3.36% other constituents.
With an annual milk production of 187.7 million tonnes and per capita milk availability of 394 gms/ day in the year 2018-19, India is the world’s largest producer and consumer of milk, yet it neither exports nor imports the milk. In the recent past, there is a growing public health concern, especially regarding the food we take and extreme impetus is being given on the quality of milk.
The protein found in milk is 80% casein and 20% whey. Beta-casein is the second most abundant casein type in cows’ milk and comprises 30% of total milk casein protein. There are two families of beta-casein protein found in milk, known as A1 and A2 beta-casein ‘types’. Milk that contains A1 β-Casein and A2 β-Casein are known as A1 and A2 milk respectively. A1 protein variant is commonly found in milk from crossbred and European breeds of cattle and A2 milk is found basically in indigenous cows and buffaloes of India (Asia as a whole).
History of A1 and A2 milk
A2 β-casein is the protein that has been produced from the cows, since before they were domesticated over 10,000 years ago. It has no known negative effects on human health. In the past few thousand years, a natural point mutation occurred which resulted in a proportion of cows of European breeds producing a casein variant called A1 β-casein. This happened because the gene encoding β-casein was changed such that the 67th amino acid in the 209 amino proteins was switched from proline to histidine. Histidine promoted cleavage of the 209 amino acid chain at 67th amino acid position due to which beta casomorphine-7 (BCM 7) was formed in human digestive system after cleavage. In simple words, BCM 7 is the peptide released by digestion of casein. This BCM 7 is harmful to human body in a number of ways. Slowly, this protein variant became dominant in milk which resulted in A1 milk. This new kind of β-casein that was created came to be known as A1 β-casein which is found in the milk of many crossbred cows such as Holstein Friesian and Jersey cross-bred cows in India.
Basic genetics of A1 and A2 milk
The A1/A2 status of a cow is determined by a pair of genes on the sixth chromosome. There
are two major alleles of the gene i.e. A1 and A2 beta-casein alleles. A cow carries two copies of the beta-casein gene; it can carry either of A2A2 (homozygous), A1A2 (heterozygous) or A1A1 (homozygous) alleles. Neither allele is dominant over the other rather; they are codominant i.e. additive in their effect. Therefore, an A1A2 cow will produce A1 and A2 beta-casein in equal amounts. An A2A2 cow will only produce A2 beta-casein and an A1A1 cow will only produce A1 beta-casein. The Northern European breeds of cows such as Holstein Friesian carry the A1 and A2 allele at about equal levels. The Southern European breeds and the Jersey carry the A1 allele at about 35% and 2/3 of A2. Exceptionally, Guernsey breed appears to carry the A1 allele at less than 10% and the Scottish Ayrshire breed appears to be well over 50%. In addition, individual herds may carry the allele at levels that are quite different to the average for the breed. If a cow is A2A2 then she is guaranteed to pass on the A2 allele to her progeny. Similarly, an A1 cow is guaranteed to pass on the A1 allele. For an A1A2 cow there is a 50% chance of passing on either of the allele.
Status of Milk protein variants in Cattle
Researches conducted on indigenous cows (Zebu type), buffaloes and exotic cows (Taurine type) have revealed that A1 allele is more frequent in exotic cattle (A1 milk) while Indian native dairy cows and buffaloes have only A2 allele and hence are a source for safe milk i.e A2 milk. The A2 allele gene in Indian milk breeds of cows and buffaloes are 100% (Red Sindhi, Sahiwal, Tharparkar, Gir and Rathi), in other Indian breeds used for farming, is around 94 per cent and while in foreign breeds (HF and Jersey), it is around 60 per cent (NBAGR, 2011). A1 β-casein is absent in the milk of pure Asian and African Cattle. So, our indigenous cows and buffaloes produce A2 milk.
Mechanism of BCM-7 generation in the Small intestine
The A1 and A2 variants of bovine β-casein differ at amino acid position 67 with histidine in A1 and proline in A2 milk. This polymorphism leads to key conformational changes in the secondary structure of expressed β-casein protein. Due to presence of histidine at amino acid 67 position, digestion of A1 β-casein milk releases a 7 amino acid bioactive peptide called beta-casomorphin 7 (BCM-7) in small intestine, while proline in A2 milk at 67 position prevents the split at this particular site and generates peptide BCM-9. It is believed that generation of BCM-7 is the major causative factor associated with A1 milk related health disorders.
Ill effects of A1 milk
The Food and Agriculture Organization (FAO, 2012) has reported an increase in many chronic diseases arising out of A1 milk. A significant relationship was observed between bovine milk consumption containing A1 beta casein and the incidence of certain diseases by many researchers all over the world.
(a) Digestive disorders
The indigestion of milk in the stomach occurs by the A1 type protein. The symptoms are stomach pain, bloating, digestive issues and respiratory problems. A confusion arises between lactose intolerance and A1 beta-casein intolerance many times. Its simple explaination is that lactose intolerance arise due to sugar in milk and A1 milk protein intolerance is due to specific A1 type protein in milk. A1 BCM-7 causes digestive problems, not because of the lactose but because of massive histamine release from casomorphin The confusion arises because the symptoms in both the cases are pretty alike.
In the gut, there are three receptors: met- enkephalin, leu- enkephalin and dynorphin. They occur in both neurons and endocrine cells. The opioid receptors are the major regulators of gastrointestinal function including motility, mucus secretion and hormone secretion. Function of opioid receptors present in the gut is hindered due to A1 BCM-7. Casein and its derivatives including A1 BCM-7 slow down gastro intestinal mucus secretion via opioid pathways, which may influence bacteria and drug absorption.
Experiments done on rats, which have same fundamental digestive system as humans and also the same range of enzyme and comparable immune system, showed that A1 beta casein slows down the transit of food through the digestive system and affects a pro inflammatory effect in the colon, both of which are opioid effects. Slower transit through the gut naturally means more opportunity for food fermentation and hence digestive discomfort, bloating and constipation. A1 beta casein causes up regulations of the enzymes DPP4 in the small intestine as a non opioid effect which causes sub-clinical inflammation and inflammatory bowel syndrome.
(b) Type 1 diabetes
Type 1 diabetes is typically diagnosed in children and it is due to the lack of insulin in the body. The studies say that drinking of A1 milk during childhood increase the risk of type 1 diabetes.
There is a consensus that type 1 diabetes is caused by one or more environmental trigger which in generally susceptible people, promotes and destroys the insulin secreting Beta cells. The strength of the co-relation between countries, of their A1 beta casein consumption and their incidence rate of DM 1 is extremely high. The animal study shows that there is very little effect of a diet high in A1 beta casein on the development of diabetes. It is known that A1 beta casein 4 is cleaved enzymatically in the gut to produce a molecule which has some morphine-like actions in the body and it is postulated that this may influence the immune surveillance. Beta casomorphin-7 has opioid properties including immunosuppression which could acount for the specificity of the relation between the consumption of some but not all beta casein variants and diabetes incidence.
(c) Sudden infant death syndrome (SIDS)
Sudden infant death syndrome (SIDS) is the most common cause of death in infants less than one year of age. In developed counties, it is the biggest case of death in apparently healthy babies. SIDS is defined as the unexpected death of an infant, without an apparent cause. Some researchers have speculated that BCM-7 may be involved in some cases of SIDS. One study found high levels of BCM-7 in the blood of infants who temporarily stopped breathing during sleep. This condition, known as sleep apnea, is linked to an increased risk of SIDS. These results indicate that some children may be sensitive to the A1 beta casein found in cow’s milk. It could be that the BCM7 is being transferred through the blood. But it is looking increasingly likely that it might also be via other mechanism perhaps including the lymph system. Regardless of how it is occurring, there seems little doubt that bovine BCM-7 can get into human breast milk and that it can cause life threatening event in babies. So, the evidence indicates that it is not only the babies but also the lactating mothers, who need to be on cow’s milk that is free of A1 beta casein. However, further studies are needed before any firm conclusion can be reached. There are some options for reducing the risk of this disease. It seems that the mothers herself should drink the A2 milk so as to reduce the risk of producing A1 type casein in their milk and when babies are weaned, they should also be made to drink the A2 milk. In this way, we can reduce the death of infants.
(d) Risk of heart diseases
Studies shows that A1 beta casein promotes the fat build up in injured blood vessels. Fat accumulation may potentially clog blood vessels and cause heart disease. Ischemic heart disease and stroke represent the clinical outcome of pathogenic processes that occur over decades and these process are multi-factorial and several risk factors have been well established.
One study shows that as a direct effect of consumption of A1 and A2 milk, atherosclerosis development was examined in rabbits. Compared with A2 beta casein, the A1 type had some effect on blood vessel functions, blood pressure and inflammation. It is concluded that beta casien A1 is atherogenic compared to A2 beta casein. The study is not performed on human so more research is needed.
In many of the medical literature, we get to know the link between the development of ischemic heart disease (CVD) and specific milk protein intake. Besides, some populations such as the Masai (East African) and Samburu (Northern Kenya) had virtually no heart disease despite consuming a diet rich in animal milk but that milk, fortunately, came from Zebu cattle which is a breed that carries the A2 allele exclusively. Western countries, which had similarly high bovine milk consumption from predominantly the Holstein breed, Jersey and other breeds had a greater incidence of CVD than nations with low milk consumption. It is so because people of small nations consume A2 milk. The epidemiological analyses concerning the two alleles of β-casein and the incidence of CVD underscores the apparent relationship between the risk of chronic disease and A1 BCM-7 intake.
(e) Autism and Schizophrenia
Autism is a mental condition characterized by poor social interaction and repetitive behavior while schizophrenia is a psychological disorder. In theory, peptides like BCM-7 might play a role in the development of autism. However, studies do not support all of the proposed mechanisms. One study of infants found higher levels of BCM-7 in those who were fed cow’s milk, compared to those who were breastfed. However, levels of BCM-7 dropped quickly in some of the infants, whereas they remained high in others. For those who retained these high levels, BCM-7 was strongly associated with an impaired ability to plan and perform actions. Another study indicated that drinking cow’s milk may worsen behavioral symptoms in autistic children. On the other hand, some studies found no effects on behavior. So far, no human trials have specifically investigated the effects of A1 and A2 milk on symptoms of autism. There is no conclusive evidence about the effects of A1 milk on autism. However, the issue is complicated and needs to be studied further.
(f) Magnesium deficiency and imbalance
An average person is able to get only about 700 mg of calcium per day, which comes primarily from dairy products. This amount is against the recommended amount of 1,000–1,500 mg.
Calcium content of milk may reduce the risk of osteoporosis and colon cancer as well as including milk in the diet may promote weight loss. The ideal calcium to magnesium ratio for the human body should be 2:1 while the A1 milk’s ratio is 10:1. By relying on A1 cow’s milk for calcium, we will have magnesium deficiency and imbalance because for 10 parts of calcium in A1 milk, 5 parts of magnesium will be required but this requirement is not fulfilled. A2 milk does not cause such imbalances. So, A1 milk will lower magnesium levels whereas A2 milk does not. Magnesium helps improve digestion, is anti-inflammatory in action, involved in nerve and muscle function, is a de-toxifier, increases alkalinity of the blood and flexibility of the tissues. Magnesium is required for the body to produce and store energy, hence very important for the body. By evidence ,A2 milk consumption results in a more healthier and stronger dentition with lesser skeletal jaw based discrepancies as was noted in an epidemiological study conducted on 500 school going children. It was observed that more dento-facial deformities were apparent in those children who consumed A1 milk than A2 milk.
Along with the above mentioned disease conditions, the inflammation from A1 milk casein causes lymphatic congestion and metabolic suppression. It worsens acne, eczema, upper respiratory infections, asthma and allergies. Ear infections, bronchitis, tonsillitis are also caused by A1 BCM-7. A1 milk casein causes endometriosis because of its inflammatory and immune-disruptive effect. Endometriosis is a gynecological condition in which cells from the lining of the uterus (endometrium) appear and flourish outside the uterine cavity, most commonly on the
membrane which lines the abdominal cavity.
National and International market of A2 milk
It is generally believed that the Indian cows are low in productivity. It is for this reason that the Indian cows are despised at home. But over a half a dozen Indian cow breeds, which include Gir, Kankrej, Sahiwal and Ongole among others, are doing exceptionally well in Brazil. Milk yield from Gir in Brazil have now crossed 70 litres. Ironically, semen of pure-bred Indian breeds is now being imported from Brazil into India.
Sale of healthy A2 milk in Britain and Ireland has reached Rs 10 crore in just one year after its launch. A2 milk is now available in 1000 stores across UK and Ireland including big retailers like Tesco, Morrison and Co-op. In Australia and New-zealand, A2 milk is now growing the fastest with a share of 8 percent of the milk market, the sales increasing by 57 percent in a year.
Pepsi foods has also been on the fore-front, and now plans to take A2 milk to the European market outside Britain. Meanwhile, China too has emerged as a strong market for A2 milk after the scandal surrounding the sale of spurious baby powder some years back. It is expected that the China’s intake of A2 milk in the rapidly growing infant food market will double by 2020.
In India, few brands like Desigo, Pathmeda and AMUL have started the commercial sale of A2 milk. Desigo milk brand traces back its origin in Rajasthan and its availability is in western India along with parts of NCR region. The price of A2 milk sold by it is Rs. 60-80/ liter. Pathmeda brand of A2 milk, also, has its origin in Rajasthan and its availability is in the parts of western India. The price of the A2 milk sold by this brand ranges from Rs. 40-50/ liter. These two brands exclusively use the milk from the native Indian breeds of cattle. AMUL has its origin in Gujarat and its availability is spread all over the country. The price of the A2 milk sold by this brand is Rs. 70/ liter. There are a few other brands which have commenced to sell A2 milk commercially but a significant market of A2 milk in India has been captured by afore mentioned brands. Delivery of A2 milk through online order to various shopping websites like shopapni.in is the new trend that is being followed by many people.
A2 milk in India – Constraints
There are various hurdles in the path to commercialize A2 milk in India, major being intensive cross-breeding programmes running widely through various government schemes all over the country. These programmes are badly exhausting the germplasm of Indian cattle breeds. In India, the population of exotic/ crossbred milch cattle increased from 19.42 million to 25.67 million, with an increase of 32.2 % (20th Livestock Census- 2019). Due to decrease in the number of indigenous cows, total production of A2 milk is declining gradually. No modified methods to demonstrate technical quality of milk and less awareness among people regarding the harmful effects of A1 milk add to this list. A2 milk, if researched in Indian goat breeds, can be path-breaking both from commercial and health viewpoint, but scarce work has been done in this direction.
Conclusion
A2 milk (Desi cow’s milk) should only be recommended as it prevents the human beings from milk-related health complications, which are due to A1 milk (Exotic cattle’s milk). Our country needs to generate awareness regarding the ill-effects of A1 milk which is presently being consumed by a large population of our nation.
India is, finally but not completely, waking up to the importance of its native cow breeds. After the government provided some funds to the Gokul Mission, Ministry of Agriculture is setting up two research stations for improvement of the neglected breeds. One is in Mathura while the location of the other is still not finalized. Rajasthan is the first state to appoint the minister of cow affairs. Haryana CM, Manohar Lal Khattar, has signed a MoU with Gujarat under which semen of Gir cows will be made available for developing 1,00,000 cows of local breeds.
It’s the nation’s responsibility to cease cross breeding programmes and protect purity of desi breeds like Ongole, Gir, Tharparkar, Hallikar, Kankrej, Deoni, Kangayem, Nagpuri and Vechur. In this aspect, government’s support is needed to accomplish the conservation of indigenous breed’s purity and to reach to a developed concept in the evaluation of milk quality. Also, more research work is required to further investigate the hypothesis of A1 and A2 milk.
