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“Make low protein doses more beneficial”

Elderly need no less than the protein equivalent of a 120-150 grams of chicken breast or 1-1.5 litres of milk in order to increase post-exercise muscle-protein synthesis rates. Dr Andy Holwerda therefore investigated strategies to make low protein doses more beneficial. The TiFN PhD fellow defended his thesis at Maastricht University, March 21.

While studying Human Movement Sciences, in his native country Canada, Holwerda became fascinated by the impact of nutrition and exercise on muscle mass regulation. “I knew, immediately, that this would be my field”, he says. After graduating he saw TiFN as the perfect PhD opportunity. “Luc van Loon, my promotor and a leader in the field, has been closely involved in the TiFN collaboration.”

Age-related muscle wasting
Holwerda investigated muscle protein synthesis following protein ingestion, which declines in the elderly. “Anabolic resistance partly explains the decline”, he says. Earlier research demonstrated that physical activity, in particular resistance exercise, most-effectively increases muscle mass.

Labelled-isotope techniques
Holwerda used isotope-labelling to determine how much protein is required to stimulate near-maximal muscle protein synthesis rates in healthy older men. He learned that people need 30-45 grams of protein to affect synthesis most positively. “Ingesting so much protein in a single mixed meal may be challenging, especially for the elderly”, says Holwerda.  “30-45 grams of protein is the equavalent of approximately 120-150 grams of chicken breast, 1-1.5 litres of milk or 300-400 grams of quark. “Therefore we need strategies to make lower-protein doses more beneficial.” Co-ingesting leucine shows promise, as do taking supplements or protein shakes immediately after exercise and/or before sleep.

Award
After graduating, Holwerda will stay at Maastricht University, further optimising his method – developed during his PhD – for long-term assessment of muscle-protein synthesis, for which he received the Kootstra talented researcher fellowship.  “I will investigate the effects of sleep, hormonal fluctuations and regular physical activity on muscle synthesis”, he explains.

Holwerda values his time at TiFN. “I experienced many disciplines and learnt how to collaborate with industry partners – very useful for when I have my own lab.”