Farm fresh milk keeps kids healthy

A European study has shown that infants fed on fresh, unprocessed milk rather than UHT milk are less prone to infection. The research, which was published in the Journal of Allergy and Clinical Immunology, found that fresh cow’s milk protects young children from respiratory infections, febrile illness and inflammation of the middle ear.

The findings are the latest to emerge from the long-term PASTURE study, which is exploring the role of dietary and environmental factors in the development of allergic illness. The study initially recruited 1000 pregnant women who were asked to document their children’s diet and state of health at weekly intervals during the first year of life.

“Among children who were fed on fresh, unprocessed cow’s milk the incidence of head colds and other respiratory infections, febrile and middle-ear inflammation was found to be significantly lower than in the group whose milk ration consisted of the commercially processed ultra-pasteurised product,” says Dr Georg Loss of Dr von Hauner Hospital, first author of the paper.

Ingestion of farm milk reduced the risk of developing these conditions by up to 30%, and the effect was diminished if the milk was heated at home before consumption. Conventionally pasteurised milk retained the ability to reduce the risk of febrile illness, while exposure to the higher temperatures used in UHT processing eliminated the effect altogether. Importantly, the positive impact of raw milk could be clearly separated from the confounding effects of other elements of the children’s nutrition.

“The effects of diverse milk treatments are presumably attributable to differentially heat-resistant components present in fresh milk. Compounds that are sensitive to heating seem to play a particularly important role in protection against respiratory-tract and ear infections,” says Loss.

Industrial processing of milk involves short-term heating of the raw product. Conventionally pasteurised milk has been exposed to temperatures of 72-75°C for 15 seconds, while ultra-pasteurised milk undergoes heating at around 135°C for a few seconds.

The researchers point out that consumption of untreated milk carries its own risks, as the product may contain pathogenic bacteria that cause serious illnesses, including the enterohemorrhagic Escherichia coli (EHEC) strains that are associated with severe diarrhoea and kidney failure, and the microorganisms that cause listeriosis and tuberculosis. The researchers therefore suggest that alternative processing methods are needed for the industrial treatment of raw milk. “With novel, milder treatments one could produce milk that is free of pathogenic microorganisms but retains the protective agents found in fresh milk,” says Loss.

In addition to fats and carbohydrates, cow’s milk contains proteins that can modulate the function of the immune system. “In many respects, the composition of cow’s milk is similar to that of human milk,” says Loss. It has long been known that breastfeeding protects infants from infection, although how milk actually affects the early immune function remains unclear.