Leucine, Whey and Rice Protein
In January, I made a post saying that there was scant evidence that branched chain amino acids (BCAA) are important for sports nutrition (Branched Chain Amino Acids and Exercise). In response, a reader, who is a bodybuilder, told me that while BCAAs might not be important, leucine (one of the three BCAA) is likely important and is probably the reasons why whey protein powder has been shown to be better than soy for building muscle.
The reader passed on some abstracts and I found some others.
One was a study that showed that after 12 weeks of exercise in untrained men, 4 g/day of leucine led to a 41% increase in strength compared to a 31% increase for the placebo which was lactose. There were no differences in muscle mass. Okay, but is a 10% greater increase in untrained men really enough to worry about? Assuming that just eating 4 more grams of protein per day wouldn’t be just as good, I’d be surprised if the lactose group wouldn’t catch up if given a few more weeks of training.
Another two abstracts were studies comparing whey protein to soy: one in older men (2) and one in younger men (3). Both were simply measuring muscle synthesis one time after one bout of exercise. Free versions of both studies are linked from the abstracts below (I didn’t bother reading them). I don’t think these studies prove much and I don’t know if there are more impressive studies showing whey protein to be superior to soy.
Then in March, a study was reported that showed that rice protein was as effective as whey protein in increasing muscle mass (4). As of today, it does not appear to have been published in a peer-reviewed journal. This study was better designed (for our purposes) in that it was done on men who had been already involved in weight training. It was double-blinded and after 8 weeks of supplementing with one of the proteins at 48 g/day, there was significant increases in strength and muscle mass. There was no placebo group so who knows if either type of protein was necessary – perhaps just taking part in a study would be enough motivation to work out harder and have some gains in muscle mass.
In short, I don’t think there’s anything to worry about for vegan bodybuilders who are concerned that their soy or rice protein powders are not giving them the same edge as bodybuilders using whey protein.
Please note that I am not philosophically opposed to the idea that plant proteins might be inferior or to supplementing for better athletic performance. I think there is good evidence that elite vegan athletes might benefit from creatine (for recreational athletes, creatine’s probably not worth the hassle). But one should be very skeptical when it comes to sports nutrition supplements – there is a lot of money and enthusiasm behind finding supplements that can improve performance, but most turn out to be useless.
1. Ispoglou T, King RF, Polman RC, Zanker C. Daily L-leucine supplementation in novice trainees during a 12-week weight training program. Int J Sports Physiol Perform. 2011 Mar;6(1):38-50. | link
2. Yang Y, Churchward-Venne TA, Burd NA, Breen L, Tarnopolsky MA, Phillips SM. Myofibrillar protein synthesis following ingestion of soy protein isolate at rest and after resistance exercise in elderly men. Nutr Metab (Lond). 2012 Jun 14;9(1):57. | link
3. Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol. 2009 Sep;107(3):987-92. | link
4. Dutch, A. First Double Blind Study Proves Plant-based Rice Protein Has Identical Benefits To Animal-based Whey Protein. PR Newswire. March 11, 2013. | link