At around the age of 50 the ageing processes begin to affect the body. Among other things, an increased loss of muscle mass can occur, which - when not sought counteracted - results in a noticeable physical weakness and reduced physical function, with an increased risk of accidents such as falls. Epidemiological studies reveal that for many elderly people the required protein intake is not met. Dietary protein is the most potent nutrient to build up skeletal muscle. To what extend daily supplementation with dietary protein can slow down the loss of muscle mass and function, and whether the quality of the dietary protein is important is investigated by a research team from Bispebjerg Hospital – with the help from 5 cows at AU Foulum.

- Our hypothesis is that elderly people, above the age of 65, can benefit from supplementation with a dietary protein supplement on top of their normal diet. That hypothesis we will try to test. In this part, we infused an amino acid tracer into the blood of 5 cows at AU Foulum. After collecting and processing the milk we got intrinsically labelled milk proteins, which allow us to investigate how humans absorb the proteins and whether this uptake is influenced by the amount of protein we normally consume in the daily diet. The results from this experiment will reveal whether it is advisable to change the dietary requirements for the elderly, says Lars Holm, associate professor at the Biomedical Institute, University of Copenhagen and senior researcher at Institute of Sports Medicine, Bispebjerg Hospital.

The project was initiated last year and in May 2014, the researchers from Copenhagen visited Aarhus University to carry out an important part of the project at Foulum research station near Viborg.

5 cows were infused over three days with a phenylalanine amino acid tracer. The milk from 11 milkings from each cow were collected and Arla Foods processed the milk and isolated the two main milk protein fractions, whey and casein, which were returned to researchers from Lars Holms group at Bispebjerg Hospital.

These intrinsically labelled proteins will during the fall be given to elderly subjects taking part in a scientific experiment where several blood samples will be obtained from various sites as well as muscle biopsies. The experiment is funded by the Foundation of Dairy Research, Arla Foods Ingredients group and University of Copenhagen.

- Using the tracer compound, we can investigate how fast the test persons absorb the milk proteins and how much of the amino acids from the milk proteins that end up in the blood stream. Some of the amino acids will be metabolised for energy, but many will be built into new proteins, for example in the skeletal muscle, explains Lars Holm.

Other test persons will take part in the larger study and followed for a year, during which period their protein uptake is altered. A range of various measurements as well as questionaires and observational methods will be applied to these subjects in order to reveal the effect of an increased protein uptake upon muscle mass.

Further information: Associate professor Lars Holm, Biomedical Institute, University of Copenhagen and the Institute of Sports Medicine, Bispebjerg Hospital, e-mail: larsh@sund.ku.dk