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First ever study looks at soy-dairy blend for muscle building

Kathleen Blanchard's picture
Muscle building gets a boost with soy and dairy blend, in first ever study.

If you’re looking for a way to build lean muscle after resistance training, or just stay strong with aging, consider mixing up a bit of protein from dairy and soy. New findings show the combination works better than either protein alone for muscle building.

The new study, published in The Journal of Nutrition, shows proteins from soy combined with the dairy proteins whey and casein extend amino acid delivery to the muscles to prolong protein synthesis needed for strong muscles.

Blake Rasmussen, Ph.D., interim chair, Department of Nutrition & Metabolism and principal investigator of the study explained in a press release the protein sources are high quality and have all the essential amino acids believed to stimulate muscle growth.

“This is the first study to test the effects of combining soy with the dairy proteins, whey and casein, for promotion of lean body mass gain”, Rasmussen added.

Beverages used in the study contained 20 grams of protein from either the soy-dairy blend or whey protein. Both contained equal amounts of leucine, an amino acid involved in the body’s muscle growth cell signaling pathway.

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The soy dairy protein blend used was 25 percent SUPRO® isolated soy protein, 25 percent whey protein isolate and 50 percent caseinate that was compared to whey protein.

Nineteen healthy participants were included in the study who consumed the beverages after performing high resistance leg exercises. The researchers collected samples from muscles at rest and again at 3 and 5 hours after exercise.

Paul Reidy, lead investigator says past studies have focused on single sources of protein for muscle building; ignoring leucine content that has an anabolic effect on muscles.
“Results from our study with matched leucine indicate the soy-dairy protein blend stimulated muscle synthesis during the early recovery period as well as into the later post-exercise period, compared to the single protein treatment, whey, which only increased muscle synthesis from rest into the early recovery period”, Reidy said.

The finding has implications for young active and older adults alike. Maintaining muscle mass with aging especially can lead to fewer disabilities and increased quality of life for millions of Baby Boomers.

Proteins from eggs, beef, milk and whey are all known to help build strong lean muscles. The new study, which is the first to examine the effects of different proteins for muscle strength after training, shows the soy-dairy protein blend has added benefits of extending amino acid delivery after exercise for muscle building.

J. Nutr. March 1, 2013jn.112.168021

Image credit: Morgeufile