After the positive feedback of a post I wrote regarding the different types of protein, I have decided to delve deeper into the research and provide a more detailed response. Most information about protein powders originates from the ignorant mouths of those with a vested interest in selling the stuff. Once in a while someone escapes that mess. Please allow me to help everyone who wants to hop off the bro bandwagon and consider the factual evidence. If one thing is certain, scientific literature has demonstrated that faster cannot be assumed to be better when it comes to promoting net anabolism.
There’s really no staggering difference in the performance of the popular types of protein on the market, no matter how desperately companies try to hype them up. Assuming that someone is consuming sufficient total daily protein from a variety of high-quality sources, then their bases will be covered, regardless of differences in protein type. However, if I were forced to name the "best protein powder for gaining muscle", it would be a protein blend with a mix of high-quality sources. There is emerging data that fast proteins alone are not the optimal choice for promoting lean body mass gains. Slow proteins or a combination of slow and fast proteins appear to be more effective. Let's consider the post-workout protein shake, which is only popular due to a misunderstanding about the need to frantically cram nutrients during a short period of opportunity, commonly known in bro circles as the "magic anabolic window". In reality, the receptivity of muscle to protein dosing can persist for at least 24 hours after a training session (link). Again, as long as macro targets for the day are hit, it's highly unlikely to make any measurable difference whether it's whey, casein, or a blend. Both proteins are high-quality, and both are effective. They have different absorption kinetics, but the difference they have on net muscle protein accretion appears to be negligible, especially within the context of the diet as a whole, which contains other protein sources. Having said that, the combination of whey and casein should be superior to either in isolation. The whey provides a quick hit of aminos to boost protein synthesis while the casein provides a longer source of aminos to blunt protein breakdown. You get a spike from the whey along with a sustained level from the casein, plus you get slightly different amino acid profiles.
A comparison study of whey, casein, and milk protein revealed that total milk protein (about 80% casein and 20% whey) had the "best nutritional quality" and lower rates of deamination/conversion to urea than either micellar casein or whey protein in human volunteers. The researchers suggested that this was due to synergistic effects between the two (link). Total milk protein was the superior performer in all parameters, with casein in the middle, and whey in last place. Quoting from the study, "In conclusion, we showed that a slowly digested protein induced better postprandial utilization of dietary nitrogen than did a rapidly digested protein, despite the high chemical score of MSPI. This result, together with the hypoaminoacidemia observed 4 h after the ingestion of MSPI, strongly suggests that a too-rapid dietary AA delivery cannot support the anabolic requirement throughout the postprandial period."
In terms of strength and body composition, another study compared the effects of three treatments on resistance-trained men: 40g whey + 8g casein; 40g whey + 3g BCAA + 5g glutamine; 48 grams of carbohydrate. The supplements were ingested post-workout and on the mornings of non-exercise days. The casein/whey group had the greatest increase in lean mass, the carbohydrate group came in second without any gain, and the whey/BCAA/glutamine group actually lost lean mass (link). "Significant improvements in both lean mass and fat-free mass were found for the whey protein with casein group, as determined by DEXA, compared to the other 2 groups. While this finding was unexpected at the time the study was conducted, it is not surprising upon consideration of some recent findings. It has been well documented that whey and casein possess different patterns of amino acid release, which has been shown to greatly affect the extracellular amino acid concentrations and the resulting levels of protein synthesis and protein breakdown."
Research has also shown that "whey and casein intake immediately after resistance exercise results in an overall equal MPS [muscle protein synthesis] response despite temporal differences in insulin and amino acid concentrations and 4E-BP1" (link). The study noted, "Taken together, it could be argued that the combination of whey and casein would be an optimal choice postexercise because whey stimulates the protein synthesis machinery with its high digestibility and consequently high peak concentrations of insulin and amino acids, including a high proportion of leucine in its composition, and casein provides amino acids for a prolonged period of time, fulfilling the amino acid need for the increased protein synthesis machinery... the ratio of whey to casein in milk could be manipulated to 50:50, thereby supplying equal amounts of fast- and slow-digested milk protein." Moreover, the International Society of Sport Nutrition recommends that when supplements are ingested, the protein contain both whey and casein components due to their high protein digestibility, corrected amino acid score, and ability to increase muscle protein accretion.
Of more interest,
at least two other published trials have shown a whey/casien blend is superior for lean mass and strength gains. In one study, milk outperformed a soy based drink (both drinks contained identical protein, carbs and calories) in terms of lean body mass gains over 3-8 weeks. Not only did the milk group gain more lean body mass, they lost a bit of fat. It was thought that the superiority of the milk was due to its slower digestion compared to the soy (a fast protein). (link) Previous results also strongly suggest that the lower postprandial retention of soy protein than of milk protein tended to be due to the more rapid appearance of dietary AAs in the blood rather than to differences in AA composition. Authors have noted that "because of differences in digestion rates, milk proteins may provide a slower pattern of amino acid delivery to the muscle than soy protein. Therefore, we propose that a difference in the digestion rate of milk and soy protein affects the pattern of amino acid appearance, which ultimately leads to differences in the net amino acid uptake and muscle protein synthesis after resistance exercise… We propose that the rapid digestion of soy protein, and therefore the faster and greater increase in delivery of amino acids from the gut to the liver, may have resulted in an increased utilization of these amino acids for the synthesis of serum proteins and urea, as seen by Bos et al, rather than for muscle protein synthesis." (link) The soy based beverage was digested and absorbed much more rapidly leading to a large rapid rise in blood concentrations of amino acids shuttling them to plasma protein and urea synthesis, whereas with milk the elevation in blood amino acids was slower and remained elevated for a more prolonged period, providing a more sustained delivery of amino acids for skeletal muscle protein synthesis. Thus, research shows that a slow or combination slow and fast protein following training appears to be superior in terms of lean body mass gains. Quoting from the paper’s conclusion: “Consumption of low-fat milk appears to create an anabolic environment following resistance training and over the long term with training, it appears that greater gains in lean mass and muscle hypertrophy can be obtained. Furthermore, milk may also lead to greater losses of body fat when it is consumed following resistance training.”
I will allow AlanAragon to summarize the findings: "Does casein slow down the absorption of whey? Yes, but this is not at all a bad thing... Casein allows IGF-1 to maintain its binding capacity & structure whereas IGF-1 would normally undergo significant denaturation by the time it hits the blood. This quality tends to counterbalance & even supercede its slow absorption & processing. Whey does not exert these same positive effects on IGF-1 the way casein does, nor does it have the same positive effect on nitrogen retention. In research done by Demling & DeSanti, resistance trained healthy subjects who received a casein-dominant blend had approximately 100% better strength & lean mass gain along with another 100% greater loss of fat compared to the comparison group who received straight whey without casein. It doesn't get any clearer than this [link].
Wipe away all the marketing you've been hypnotized by, & try to understand that there is nothing particularly special about making sure casein doesn't get in the way of whey absorption. In fact, to play devil's advocate, one might better ask why include any whey if it's gonna get in the way of casein. The answer to this is that whey contains, among other things, a significant hit of much needed BCAAs, a uniquely anabolic amino acid profile, and it also can synergize with milk/casein to hike insulin levels beyond either protein source by itself. Chemical teamwork."
Further reading that may be of interest:
[link] "The timed release of amino acids into the circulation is associated with greater SMPS [skeletal muscle protein synthesis] rates and lean body mass gains. These authors attributed the benefits of the protein blend to differences in digestion rates that prolonged the increase in blood amino acid levels, resulting in greater muscle amino acid uptake. Blending [proteins] also creates a more balanced amino acid profile, specifically for BCAAs, glutamine, and arginine. This may confer an advantage because a more balanced amino acid profile might provide for a wider range of benefits (e.g., acid-base balance, growth hormone release, enhanced muscle blood flow, immunity) than a single protein source rich in only 1 or 2 of these key amino acids.
[link] A new study on protein blends released Jan. 2013 (full text not available to me yet)
Bookmarks