A new study published in the American Journal of Clinical Nutrition demonstrates that whey protein is significantly effective in producing muscle gain, at least in older men.
For years, bodybuilders, fitness buffs and people just generally into healthy living have debated the relative merits of different types of protein powder.
For the average person, choosing a protein powder can be confusing. There’s rice protein, casein (milk protein), whey protein and soy protein, just for starters. Some are digested more slowly, some are available to the body much more quickly (whey, for example).
But studies testing one against the other for muscle growth are few and far between.
In the current study, 48 older men were assigned to ingest 20g (one typical serving) of either whey, casein, or casein hydrolysate (a faster acting form of casein). The researchers then used a number of sophisticated measurements to asses both digestion and absorption; they also calculated how effectively new muscle was created.
The clear winner was whey protein.
“Whey protein stimulates… muscle protein accretion (growth) more effectively than do casein and casein hydrolysate in older men”, the researchers concluded.
Scientists believe that a particular amino acid- leucine- may be partly responsible for the positive effect on muscle growth. Leucine has been identified as the main nutritional “signal” responsible for stimulating muscle growth, and whey has a considerably higher leucine content than other protein powders.
Other studies have demonstrated the positive effects of whey protein powder on both appetite control and on the immune system.
Though this particular study was done on older men, there’s no reason to assume that the positive effect on muscle growth would not apply to other populations as well, such as women and younger men.