Scientists have found a model for studying some of our fastest rising diseases, and it was tucked away at the back of the fridge. Although ultra-high temperature (UHT) milk lasts much longer than ordinary pasteurized milk, it will eventually turn into an undrinkable gel. The process by which this occurs may help us understand the formation of amyloid fibrils in Alzheimer's and Parkinson's disease and possibly even type 2 diabetes.
Milk straight from the cow contains a lot of bacteria, which multiply until they are dangerous to consume. Normal pasteurization kills most of these bacteria, leaving the milk safe to drink for a week or so. Longer and higher temperature processing kills all the bacteria, for a longer-lasting – albeit less tasty – product. The treatment also has a strange effect on the milk's proteins, however, particularly κ-Casein and β-Lactoglobulin.
These two are quite unrelated to each other, but heating eventually causes them to combine to form insoluble amyloid fibrils. The process by which this occurs has been much debated, but in the journal Small, a team led by the Australian National University's Professor John Carver reveal the chemical bonds that link these aggregations.
Carver described the process to IFLScience as “cross-seeding or cross-templating”, where changes to one protein is reflected in the other.
Food manufacturers aside, the thing that makes the discovery exciting is the parallel to the formation of beta-amyloid plaques and tangles of tau proteins in the brains of people with Alzheimer's disease. Both are aggregations with similarities to those Carver explored.
Similar structures of different proteins are observed in Parkinson's disease where, as in Alzheimer's, they appear to be associated with devastating cell death. Even type 2 diabetes sees the formation of protein aggregates in the pancreas, although Carver told IFLScience the connection to cell death is not as clear.
The proteins for all these diseases are different from those in milk, and there is no reason to believe drinking UHT milk causes any of the conditions, but there may be a common process for amyloid formation. If Carver's work can shed light on the aggregation process, it might open the door to prevention, or even ways to reverse the damage.
“Perhaps the stress of heat processing mimics the effects of aging [in the body],” Carver told IFLScience. Carver floated the possibility that these sorts of fibrils form in organs all the time, but a healthy body has ways to break them down before they can do damage. Whether this is true or not, he added: “Anything we can find out about how these structures form could be of use. Probably treatment will require a multifaceted approach,” of which slowing down the aggregation process will be part.
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