There has been and continues to be an age-old debate over which protein is best. Whey Protein Isolate (WPI), Whey Protein Concentrate (WPC), Casein or a naturally occurring mix of WPI and Casein called Milk Protein Isolate (MPI)?
It’s time to separate the marketing bullshit and bro-science from the REAL SCIENCE.
Whey Protein Concentrate (WPC)
WPC offers the benefit of being well digested and fairly rapidly absorbed. Research shows amino acids in the blood peak around the 90-minute mark. One of the major benefits of WPC is the reduced amount of processing which leads to a higher level of micro fractions than its WPI sibling.
These micro fractions are beneficial for enhancing immune support, digestion and reducing inflammation.
Whey Protein Isolate (WPI)
Often referred to as the BIG BROTHER of WPC. WPI has a higher protein content, lower lactose (carbohydrate) content and is generally faster absorbed than WPC with the amino acid levels peaking around the 60-minute mark.
The downside is the lack of micro fractions in comparison to WPC.
Micellar Casein is the slower digesting protein of the diary family with amino acids peaking and maintaining around 5 hours before returning to baseline up to 8 hours after consumption. It has higher levels of naturally occurring Glutamine than Whey but lower levels of Leucine.
Casein is considered to have a greater Anti-Catabolic (muscle sparing) benefit than whey.
Milk Protein Isolate (MPI)
MPI may well be the best of both worlds (fast and slow). MPI is an isolated protein (virtually zero carbs and fats) containing whey and casein as it occurs in nature.
This mix of naturally occurring fast and slow digesting protein is exactly what the research is now showing to be most effective for building muscle.
What The Research Says...
A 2006 study comparing Whey, BCAA’s and Glutamine (WBG) to Whey and Casein (WC) showed that the combination of fast and slow digesting proteins (WC) was 200% more effective at increasing lean muscle mass (DEXA).
In this study, the WC group gained 2kg of lean muscle in 10 weeks. In addition to the increases in Lean Body Mass the subjects using the WC had better results in 1RM and Peak Power Output.
A similar conclusion came out of a Danish study where they fed young male athletes 20g of Whey or 20g of casein. The results of the study showed that Muscle Protein Synthesis (MPS) was increased rapidly with whey but dropped off quickly. Casein, on the other hand, took more time to increase MPS but maintained it for longer.
Overall, combining both Whey and Casein would have resulted in a greater gain in net MPS according to the researchers.
Casein is known for its Anti-catabolic (reducing muscle breakdown) qualities and Whey for its Anabolic (building muscle) qualities so it stands to reason that a combination of the two would be the best solution. Getting your amino acid levels above baseline rapidly after training and keeping them there for longer is the ultimate goal for building more muscle and reducing muscle breakdown.
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.