The Value of Adding Leucine to Whey
Research & Development
By Jeff Volek, PhD
Mar 20, 2014
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The essential amino acid leucine
is a major driver of the anabolic response to protein ingestion. Whey is naturally high in leucine which makes it a preferred protein source for promoting anabolism. Most whey protein contains about 10% leucine; a 20 gram serving of whey protein
delivers 2 grams of leucine. Some scientists have argued that a higher leucine intake may stimulate muscle protein synthesis further. Thus, adding extra leucine to whey may optimize the response. Others have argued that simply consuming milk, which contains both whey and casein, may be adequate to stimulate protein synthesis after exercise.
A recent study sheds light on some of these issues. They had adults at least 60 years of age consume 20 grams of whey protein with added leucine (3 g total) or a control milk product matched for calories. They performed a bout of resistance exercise on one leg 15 min before ingesting the drinks so they could measure rates of muscle protein synthesis just due to the drink (by examining the rested leg) and in response to exercise (by using the exercised leg). What they found was that just consuming the leucine-enriched whey drink resulted in a 47% increase in muscle protein synthesis, where the milk drink had a much smaller impact (10%). The increase in muscle protein synthesis in the exercised leg was also higher in the leucine-enriched whey drink (28%) versus the milk drink (3%). These results support the use of whey protein with added leucine as superior to a traditional dairy product for stimulating muscle protein synthesis in healthy older subjects.
Luiking YC, Deutz NE, Memelink RG, Verlaan S, Wolfe RR. Postprandial muscle protein synthesis is higher after a high whey protein, leucine-enriched supplement than after a dairy-like product in healthy older people: a randomized controlled trial. Nutr J. 2014 Jan 22;13(1):9.
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