Soy-dairy blends better for muscle health

STUDIES point to soy-dairy blends as effective for individuals who are looking to improve muscle health. Compared to whey alone, a protein blend of soy, casein and whey can benefit post-workout by prolonging the delivery of select amino acids to the muscle for an hour longer. There is also prolonged increase in amino acid net balance across the leg muscle during early post-exercise recovery, suggesting longer muscle building. These are highlights of a research by Blake B. Rasmussen, Ph.D., chair, department of Nutrition & Metabolism at the University of Texas Medical Branch, in collaboration with DuPont Nutrition & Health.    

“This study sheds new light on how unique combinations of proteins, as opposed to single protein sources, are important for muscle recovery following exercise, and help extend amino acid availability, further promoting muscle growth,” said Dr  Rasmussen said.

Protein needs increasing

“Because of the increased demand for high-quality protein, this study provides critical insight for the food industry as a whole, and the sports nutrition market in particular,” said Greg Paul, Ph.D., global marketing director, DuPont. “With more and more consumers recognising the importance of protein for their overall health and well-being, the results of this study have particular relevance to a large segment of the population, from the serious sports and fitness enthusiast to the mainstream consumer.”

On-going clinical study

The double-blind, randomised clinical trial included 16 healthy subjects, ages 19 to 30, to assess if consumption of a blend of proteins with different digestion rates would prolong amino acid availability and lead to increases in muscle protein synthesis after exercise.

The protein beverages given to the study subjects consisted of a soy-dairy blend (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 and up to 5 hours after resistance exercise. The protein sources were ingested 1 hour after exercise in both groups.

The study demonstrates that consuming a soy-dairy blend leads to a steady rise in amino acids, the building blocks of muscle. The data showed that the soy-dairy blend yields an increase in select amino acid delivery for about an hour longer than the use of whey protein alone. The blend also sustained a greater positive net amino acid balance than whey, suggesting there is less muscle protein breakdown during the time period shortly after consumption of a blended protein product.

The study is published in the online edition of the Journal of Applied Physiology. Further research is ongoing to identify the long-term effect on muscle mass and strength.