A1 MILK VERSUS A2 MILK

Currently, there are two primary types of milk available in the market: A1 milk and A2 milk. A1 milk originates from commercially raised cows, which are frequently given special feed and antibiotics to prevent illness. In contrast, A2 milk is produced by cows that graze on grass, and it is less readily available, mainly found in rural regions. Commercially sold milk is mainly impacted by this problem[9]. Milk that is labelled as A2 contains only the A2 type of beta-casein. A1 milk is composed solely of A1 beta casein, whereas protein is made up of a different type. The A1A2 type variant is characterized by a prevalence of the A1 protein variant. In milk from crossbred and European breeds of cattle. Milk is primarily sourced from native cattle and buffalo species. In the context of Asia overall of India (Asia as a whole) [10]. A1 beta-casein found in normal cow's milk can cause inflammation, but only in individuals who possess the enzyme capable of cleaving it to the inflammatory peptide beta-casomorphin-7 (BCM7). A1 beta-casein may also have implications in the development of autism and schizophrenia. In reality, casomorphin poses a greater threat to the brain than gliadorphin found in gluten. The drug-like properties of casomorphin are the reason it exacerbates anxiety and mood disorders and triggers cravings for dairy and sugar. Inflammation resulting from A1 beta-casein can lead to lymphatic congestion, metabolic slowdown, and weight gain. It can also exacerbate acne, eczema, upper respiratory infections, asthma, and allergies. A1 casein is thought to exacerbate endometriosis due to its potential to induce an inflammatory response and disrupt the immune system [11]. Mutations in the bovine beta casein gene have resulted in 12 distinct genetic variants, with A1 and A2 being the most prevalent among them.

EFFECT OF A1 MILK

The A1 and A2 variants of beta casein diverge at amino acid position 67, where histidine (CAT) is found in A1 milk and proline (CCT) in A2 milk due to a single nucleotide difference. A key conformational change occurs in the secondary structure of expressed β-casein protein due to polymorphism. The breakdown of the A1 variant of β-casein in raw or processed milk through gastrointestinal proteolytic digestion results in the formation of the bioactive peptide beta casomorphin 7 (BCM7). Infants are likely to absorb BCM-7 because their gastrointestinal tracts are not fully developed, whereas adults tend to accumulate the biological activity of BCM-7 locally on the intestinal brush border. In hydrolysed milk containing variant A1 of beta-casein, the level of BCM-7 is 4 times higher than in A2 milk. Preliminary research on native cows of the Zebu type, buffalo, and exotic dairy cows of the taurine type has shown that the A1 allele is more prevalent in exotic cattle, whereas Indian native dairy cows and buffalo predominantly carry the A2 allele, indicating they can serve as a source of safe milk. A link has been established between the risk of disease and consumption of a particular bovine β-casein fraction, which contains either A1 or A2 genetic variants. BCM7 is suggested to be a risk factor for human health issues as it may potentially impact many opioid receptors in the nervous, endocrine, and immune systems. This compound is also known to be an oxidant that targets low-density lipoproteins (LDL) and the oxidation of LDL is thought to play a significant role in the formation of arterial plaque. Research findings suggest that drinking milk containing beta-casein A1 is a potential risk factor for type-1 diabetes, coronary heart disease, and arteriosclerosis. Additionally, animal studies have provided evidence linking type-1 diabetes to milk consumption in general, and specifically to A1 beta-casein. Individuals who consume milk with high levels of β-casein A2, have a lower prevalence of type-1 diabetes and cardiovascular disease. The A1/A2 hypothesis is both fascinating and has significant public health implications if it is verified. Further investigation is required to establish the extent and character of BCM7 interactions with both the human gastrointestinal system and the entire body. Further research is needed involving animal studies and data collection from human subjects experiencing issues associated with A1/A2 beta-casein milk consumption [12]. Inflammation is a key underlying factor contributing to PCOS, and consequently, dairy product consumption can pose significant difficulties for women with unrecognised lactose intolerance. Many women with PCOS unknowingly suffer from a dairy intolerance, and an alarming number of them also experience gluten intolerance. In these instances, subclinical intolerance can potentially cause harm to the lining of the intestinal wall. The condition triggers an inflammatory response Research has indicated that consuming dairy products may lower the risk of developing insulin resistance and type 2 diabetes. There are numerous uncertainties surrounding the advantages in question. A 2020 literature review found no evidence of improved insulin sensitivity in women with PCOS. The condition may serve as a precursor to insulin resistance. A major research study discovered that consuming low-fat milk products every day contributed to a heightened risk of ovulatory infertility, specifically an 11% increase. Consuming an extra serving of whole milk resulted in a 50% decrease in risk. The disparity is largely due to high-fat milk having a minimal effect on elevating insulin-like growth factor 1 (IGF-1) levels. Increased levels of IGF-1 have a detrimental impact on ovarian function. The mechanisms are thoroughly comprehended. Consuming dairy products is known to elevate IGF-1 levels. Elevating androgen levels and activating other pathways leads to the development of acne. Leucine, a prevalent amino acid in dairy proteins, is also a contributing factor to the issue. Casein from dairy protein stimulates IGF-1 more so than whey does. It appears that consumption of foods rich in casein, such as cheese, may contribute to the development of acne. Whey proteins can influence insulin levels, potentially offering an alternative route to trigger acne [13]. Casein, a component of dairy protein, has a greater effect on stimulating IGF-1 compared to whey. It seems that eating foods high in casein, like cheese, could be linked to the occurrence of acne. Proteins found in whey may impact insulin sensitivity, providing a potential pathway for acne development.

EFFECT OF LOW-FAT DAIRY PRODUCTS

 Individuals with PCOS, it has been found, consume a greater quantity of low- and fat-free milk. According to previous research findings, a correlation has been established between low-fat milk and PCOS, showing a positive association. Low-fat dairy products may also raise the levels of insulin-like growth factor I (IGF-I). Some researchers have raised controversies suggesting that IGF-I could be involved in the development of PCOS. IGF-I present in human ovarian cells may induce cell activity-related alterations observed in PCOS. The relationship between the dietary-induced change in IGF-I levels and the clinical symptoms of PCOS remains unclear. Consuming low-fat dairy products has also been linked to an overproduction of androgens, which is considered one of the components of PCOS. In comparison to low-fat dairy items, whole milk and high-fat dairy products contain a greater oestrogen level. Oestrogen has been shown to lower the level of IGF-I. After the age of 18, milk is not a necessary component of one's diet, primarily due to its saturated fat content, which can lead to increased cholesterol levels. In this case, health professionals advise individuals with PCOS to choose plant-based milk over conventional milk. The individuals with PCOS condition, revealed to have a higher consumption of low- and free-fat milk. As per the results of the past studies, there is a positive relationship between low-fat milk and PCOS. Low-fat dairy products may increase the level of insulin like growth factor I (IGF-I). As some researchers have controversies, IGF-I may have a role in the pathogenesis of PCOS. The IGF-I existing in the human ovarian cells may stimulate the cell activity-related changes observed in the PCOS. It is not yet known whether the change in the level of IGF-I caused by diet may contribute to the PCOS's clinical manifestations or not. Eating low-fat dairy foods has also been accompanied by an excess of        androgens secretion known as one of components of PCOS. Compared with low-fat dairy products, whole milk and fat-rich dairy products have a higher oestrogen concentration. Since oestrogen can decrease the level of IGF-I [14].

HORMONE LEVELS BETWEEN A2 COW MILK AND CONVENTIONAL MILK

 Conventional milk may contain higher levels of hormones when compared to healthy cow’s milk (A2 milk).                            

NEGATIVE EFFECTS OF EXCESSIVE HORMONE LEVELS IN MILK

 Excess hormone levels in dairy shows some negative effects and  exacerbate the PCOS symptoms [15]