The better milk? It's in the understanding

Last Updated 22 November 2019, 20:40 IST

An anxious-looking dairy farmer, Ramachandra, approached me one early morning and sought advice for a peculiar problem. His 10-day-old female calf was vomiting after suckling her mother. There was wheatish-looking diarrhoea, too. She had been doing this for a week, but was otherwise healthy. Is it due to the A1 milk that the mother, an HF (Holstein Friesian) crossbreed, is secreting?

If the calf could not digest her mother’s milk, how will she grow? I proposed the possibility of the calf being lactose intolerant.

Accordingly, the problem gradually subsided by feeding the calf a reduced quantity of mother’s milk and then increasing it gradually, and an enzyme preparation containing lactase. A1 milk has nothing to do with it.

Similar is the case with some human beings. People with lactose intolerance (a deficiency of the enzyme lactase) are unable to fully digest the sugar (lactose content) in milk. As a result, they have diarrhoea, gas and bloating.

The condition, though harmless, has irritable symptoms. But there’s a possibility that the cause might be A1 milk. But, lactose is present in both A1 and A2 kinds of milk, and consumers should be aware that shifting from A1 to A2 milk may not help them address lactose intolerance.

Milk plays an important role in enhancing the nutritional status of millions of undernourished Indians. It provides easily-digestible protein at a relatively lower cost. However, a difference in one of the protein components in the milk produced by different cattle, termed as A1 and A2, has been drawing the attention of many scientists and nutritionists all over the globe for a decade.

It has created confusion among health-conscious consumers for its alleged health implications.

What are A1 and A2 types?

Every 100 ml of milk contains about 3.5 grams of protein. This protein is of two types — casein and whey. Beta casein is one of the subtypes of casein.

With the advent of molecular biology and biotechnological aids, scientists have identified two types (variants) in this
beta-casein protein — A1 and A2.

Genetically fixed

The production of A1 or A2 milk is completely dependent on the genetic constitution of the cattle producing it. This means that a cow producing a particular kind of milk (either A1 or A2 or a mixture of both) will continue to do so throughout its life irrespective of its feeding habits or the environment. This is more of a breed and geographic area-specific character.

Milk having A2 beta-casein gene was the wild type when the bovines were domesticated. At some point in the evolution, the A1 allele resulted due to a natural genetic mutation. Both the male and female animals transmit these genes to the next generation.

Like any other food substance, milk is also subjected to digestion once it is ingested. Beta-caseins are broken into different chemical compounds. Beta-Casomorphine7 (BCM7) is one of such broken-down product of beta-casein. BCM7 is a bioactive peptide having opioid-like activity, which is said to affect the nervous, endocrine and immune system causing health problems in human beings.

A1 beta-casein (A1 milk) produces four times more amount of BCM7 than that of A2 beta-casein in hydrolysed milk.

This is the reason behind the inference of some scientists saying that A1 milk may bring some of the health hazards.

Effect on human health

Based on the epidemiology, milk chemistry, pharmacology, animal experiments, human trials, clinical observations and consumer experiences conducted in several countries like New Zealand and Australia, reports say that consumption of A1 milk may cause more incidences of Type-I diabetes, heart diseases, arteriosclerosis, sudden infant death syndrome, autism, digestive disorders, neurodegenerative disorders, intolerance, allergies, autoimmune conditions in human beings.

“The possible ill-effects of BCM7 from A1 milk depend on whether this peptide is able to get into the circulation and cross the blood-brain barrier. In other words, it all depends upon the individual’s digestive ability to resist it,” says Dr K P Ramesha, Head, National Dairy Research Institute, Bengaluru.

The most susceptible individuals are those who already have digestive problems, infants and old people who naturally have increased intestinal porosity to absorb milk proteins.

Another set of scientists opines that evidence for a clear link between A1 beta-casein and a disease state has not been well-demonstrated.

Hence, the debate about the potential health effects of A1 and A2 milk is continuing.

There are claims that BCM7 may cause digestive issues in some consumers. Currently, there is little scientific support for digestive differences between the milk containing some A1 proteins and the one containing only A2.

On the other hand, both types of beta-casein are associated with well-established health benefits derived from their essential amino acids, calcium, and phosphorus.

Most human clinical studies comparing digestion in A1 and A2 milk have recruited participants with self-reported lactose intolerance. “If you already drink regular milk without issues, there is no reason to switch,” writes Dr Lauren Milligan Newmark, a research associate at Smithsonian Institute, California.

If you are interested to find out the milk type you consume, contact the National Dairy Research Institute, Bengaluru.

(Published 22 November 2019, 20:40 IST)

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