Protein blend may help reduce muscle loss

SARCOPENIA (strength and muscle mass declines) is a predictor of early mortality.  It is now recognized that between ages 50 and 60, muscle mass decreases at an annual rate of 1%-2%. After 60, muscle loss decreases at an annual rate of 3%.  Identifying the cause and potential therapies or preventative measures is an active area of research.  A recent study^[1], conducted in men ages 55-75 years, was completed at the University of Texas Medical Branch (UTMB), in cooperation with DuPont Nutrition & Health, and published in the Journal of Nutrition.

Both exercise and diet are important factors in maintaining muscle health but researchers have recently uncovered that the response to each becomes blunted as we age.  This new double-blind randomized controlled clinical trial compared the response to consuming two different beverages that provided different sources of high-quality protein, one hour after a bout of high intensity resistance exercise. This is the first study to investigate muscle protein metabolism in aging individuals in response to consumption of a blend of proteins, which is more representative of how people consume protein. 

The protein beverages provided to study participants consisted of a blend of soy and dairy proteins (25% isolated DuPont™ Danisco® SUPRO® soy protein, 50% caseinate, 25% whey protein isolate) or a single protein source (whey protein isolate).  Muscle biopsies were taken at baseline (before exercise) and up to 5 hours after resistance exercise to monitor breakdown and synthesis of muscle tissue using stable isotope methods. The soy-dairy protein blend induced amino acid delivery to muscle tissue, muscle protein synthesis and activated a recognized pathway that initiates muscle protein turnover. These results were similar in older adults given 30g of protein (soy-dairy blend or whey protein) after exercise.

“Our data provide additional support for the use of targeted nutritional interventions to overcome a critical condition of aging, anabolic resistance, to counteract sarcopenia,” said Blake B. Rasmussen, Ph.D., chair, department of Nutrition & Metabolism at the University of Texas Medical Branch and lead researcher of the study.  “Research conducted in both young and older subjects demonstrates the importance of delivering the amino acid leucine to promote anabolic signaling and skeletal muscle protein synthesis.  In this study, the two groups were not matched for leucine content but both groups received enough leucine to exceed the minimum threshold to shift protein turnover into an anabolic state.”

This study adds to our understanding of the response of the aging population to preventive measures, diet and resistance exercise.  The similarity between the two protein treatment groups for muscle protein synthesis and mTORC1 signaling demonstrates the role of consuming high-quality proteins for prevention of conditions associated with aging.  This segment represents a significant and increasing proportion of the population.  Focus on their specific needs will continue to grow.

“Sarcopenia is estimated to affect 30% of individuals over 60 years of age and more than 50%  of people over 80 years.  It has significant quality of life consequences for aging individuals, and contributes substantially to direct healthcare costs,” said Jean Heggie, strategic marketing lead, DuPont Nutrition & Health.  “Resistance training and dietary intervention, with a focus on high-quality protein, is certain to be part of the solution.  Lean, high-quality proteins, like soy, will have an important role in nutritional solutions targeting this condition.” 

DuPont™ Danisco® SUPRO® soy protein has been extensively studied for its benefits on heart health.  New evidence is emerging relative to soy’s ability to support other health concerns of the aging, including kidney and liver health.