Cows' milk contains a protein called beta casein, which comes in several forms depending on the genetic makeup of the cow - but what is the difference, and why does it matter?
Molecules in milk
Milk is a mixture of water, fats, proteins, sugars, and minerals. Cows’ milk contains six main proteins, one of which is called beta-casein (β-casein). β-casein makes up around 30% of thein cows’ milk and comes in different varieties, including A1 β-casein and A2 β-casein. A cow can produce one or more forms of β-casein, depending on her genetic make up.
A1/A2 beta casein and human health
The form of β-casein present in in milk may have implications for human health. It has been suggested that the A1 β-casein might lead to or aggravate Type I diabetes,and . Whereas, A2 β-casein is not associated with these diseases and might consequently be better for you. Because of these findings a2 Milk™, which has naturally maximised levels of A2 β-casein, is now being produced and marketed in New Zealand and overseas.
Truth or rumour?
In 2004, theemployed an expert, Professor Boyd Swinburn, to examine the current research on A1 and A2 β-caseins and human health. He reported that:
- Countries with high consumption of A1 β-casein had high rates of Type I diabetes and heart disease; and
- Some individuals with schizophrenia or autism show improvement when put on a casein- and gluten-free diet.
He concluded that there was no direct evidence to support claims that A1 β-casein played a role in disease, but that it was worth further investigation.
Breeding cows for β-casein
Some farmers are usingmethods to create herds of cows that only produce milk containing A2 β-casein. In other words, only calves produced by bulls and cows that have the A2 β-casein will be kept on a farm. Using this method a farmer can increase the proportion of cows in their herd that produce the A2 β-casein protein in their milk over several generations.
Farmers can tell whether a cow will produce A1 or A2 β-casein using atest developed in New Zealand by .
Written by Sara Loughnane, NZ Science, Mathematics, and Technology Teacher Fellow, 2006.