Research confirms that a protein blend outperforms whey protein alone
If you are still using a whey protein shake around workouts then you haven’t been listening to my advice over the last few years and you’re actually undermining your results. Just a few years ago we thought that whey was the absolute best protein source and only source to take before and after workouts. And it still is the best source of protein to take. It’s just not best to take it alone without other protein sources.
There is a growing body of research that now confirms that combining the fast-digesting whey protein with at least the slow-digesting casein protein is better for muscle growth than just going with whey protein alone. Some evidence suggests that an even better strategy may be to provide a medium-digesting protein, such as soy or egg protein to that mix of whey and casein. Original Research
One of the first studies to suggest that adding casein to whey is best for muscle growth comes from Baylor University (Waco, TX). They discovered that trained men following a 10-week weight-training program and taking a whey/casein blend protein shake after workouts gained 4 pounds of lean muscle mass while experiencing a slight decrease in body fat. Another group following the same training program but taking whey without casein added to it did not gain any muscle mass over the ten weeks and had a slight increase in body fat.
Research from the Mayo Clinic (Rochester, MN) later found that the reason adding casein to whey protein demonstrates better muscle growth may be due to the different digestion and absorption rates of these two different proteins. Whey protein is digested and absorbed rapidly. This means that it delivers its amino acids to the muscles ASAP, which spikes muscle protein synthesis sky high. This is one property of whey protein that makes it superior to other protein sources, yet not perfect. Its speed of digestion and absorption is its benefit, but also its downfall. The problem with whey being absorbed so quickly is that it gets to the muscles and spikes muscle protein synthesis, but then it is used up and protein synthesis drops sharply.
Casein protein, particularly micellar, is digested and absorbed at a slow and steady rate. The research from the Mayo Clinic found that adding it to whey protein allowed the amino acids from casein to continue supplying the muscles long after the amino acids from whey were gone. Amino acid retention in the muscles studied was significantly higher 4 hours later when amino acid retention from whey was barely noticeable. This essentially prolongs the anabolic response initiated by the whey protein, which leads to greater muscle growth
The two latest research studies on protein blends versus whey alone come from the University of Texas Medical Branch (Galveston, TX). This lab, by the way, has been a leader in helping us better understand protein intake around workouts, muscle protein synthesis, and muscle growth.
The first study published in 2013 had men consume 20 grams of whey protein or 20 grams of a whey/soy/casein combo one hour after a leg workout. The combo was 25% whey (5 grams), 25% soy (5 grams) and 50% casein (10 grams). They reported in the Journal of Nutrition that both the whey protein and the mixed protein increased muscle protein synthesis to a similar degree. However, the mixed protein maintained that higher rate of protein synthesis for hours longer than the whey protein alone.
A 2014 follow-up study by the UTMB researchers also provided the same amount and kind of whey, casein, and soy blend protein shake or a solely whey protein shake one hour after a leg workout. They reported in the Journal of Applied Physiology that the whey, soy, and casein blend led to a prolonged and greater net amino acid balance. Taken with their previous study, these results basically mean that when you use a protein that contains a very fast-digesting protein (whey), a medium-digesting protein (soy or egg), and a very slow-digesting protein (casein) postworkout, more amino acids from the protein are taken up by the muscles for a longer period of time, they elevate muscle protein synthesis for a longer period, and they result in more muscle protein being built, which can result in greater muscle size and strength compared to if you took just whey protein alone postworkout.
Although both the UTMB studies, as well as the Baylor study provided the protein blends postworkout, I believe that you not only want a protein blend after workouts but also preworkout and/or during if you do a pre/during/post shake like, as well as any other time of day that you have may have a protein shake, such as in the morning when you wake, before bed, and between meals. The Mayo Clinic study supports this line of thinking as they supplied a whey/casein protein blend during rest and if further enhanced amino acid uptake in the muscle fibers. Plus, this recommendation has worked very well for thousands of people who have followed my advice over the years.
Although the UTMB researchers used soy as the medium-digesting protein in the blend with the fast-digesting whey and slow-digesting casein, egg also makes a great medium-digesting alternative. In fact, it can be argued that using egg is even better than soy since evidence suggests that soy is less anabolic than milk proteins (whey and casein) and egg protein. In fact, in my protein blend, I use egg white protein as the medium-digesting protein for a number of reasons. For one, it is more anabolic than soy. Another reason is that it is next to impossible to find soy protein that is non-GMO (genetically modified organism). Many people are fearful of the unknown health consequences of GMOs. And the third reason is that many still believe that soy will reduce testosterone levels and increase estrogen levels in males. Based on the real research, I feel that there really is no evidence or just very weak evidence that soy lowers testosterone. Yet, I still used egg for the other main reasons. Regardless of the source of the medium-digesting protein, the more critical elements of the blend appear to be the two milk proteins whey and casein.
What may be surprising about the UTMB studies to many people is that the protein blend used in the studies that proved to be superior to whey alone was only 25% whey protein and 50% casein. It appears that just a small amount of whey is needed to quickly get some amino acids to the muscle and spike muscle protein synthesis up to maximal levels. But then you need a bit more casein to keep amino acids going to the muscles for several hours later to keep muscle protein synthesis elevated for longer and promote greater muscle growth.
The UTMB researchers did not investigate different ratios of whey and casein. They used the same 25% whey, 50% casein, and 25% soy in both studies. This does not mean that this is the ideal blend, but it does show that just 25% whey protein should be adequate. The research that I have done in the actual gym with real hardcore lifters suggests that the best blend is actually 50% micellar casein (not caseinate), 40% whey protein, and 10% egg white protein. Although I don’t have data on protein synthesis or amino acid net balance in muscle fibers, I do have a lot of data showing superior gains in muscle size and strength from this precise blend compared to other ratios.
Kerksick, C. M., et al. The effect of protein and amino acid supplementation in performance and training adaptations during ten weeks of resistance training. Journal of Strength and Conditioning Research 20(3), 643–653, 2006.
Soop, M., et al. Coingestion of whey protein and casein in a mixed meal: demonstration of a more sustained anabolic effect of casein. Am J Physiol Endocrinol Metab. 303(1):E152-62, 2012.
Reidy, P. T., et al. Protein Blend Ingestion Following Resistance Exercise Promotes Human Muscle Protein Synthesis. Journal of Nutrition 143(4):410-416, 2013 .
Reidy, P. T., et al. Soy-dairy protein blend and whey protein ingestion after resistance exercise increases amino acid transport and transporter expression in human skeletal muscle. Journal of Applied Physiology, In press, 2014 .