WPC, WPI and Casein are all derived from cows milk and are exceptionally high-quality sources of protein that will support muscle growth and recovery. Per 30g serving, all three varieties provide >2.5g of leucine, the primary amino acid required to stimulate muscle protein synthesis.
As for WPC and WPI, the only significant difference between the two is the degree of processing and filtration. WPC goes through an ultrafiltration process where the filters are approximately one micrometer in diameter. WPI goes through a lengthier filtration process, with filters approximately 4 times smaller than those used to produce WPC. As a result, WPC is ~80% protein by weight, ~5-7% milk fat, and contains a moderate amount of lactose, whereas WPI is ~90% protein by weight, ~1-2% milk fat, and is virtually lactose free. Whey proteins will start to denature and coagulate after cooking for ~10+ minutes at 90 degrees C. -
Compared to whey, casein proteins have a larger molecular weight, are more heat stable during cooking, and don’t coagulate at cooking temperatures of 100 degrees C. Following filtration, casein is approximately ~80% protein by weight, ~5-7% milk fat, and contains a moderate amount of lactose. Casein is also considerably higher in calcium.
Due to their smaller molecular weight, whey proteins can be digested and absorbed at a faster rate than casein, with the potential to spike blood amino acid levels within 1-2 hours of consumption. Casein is considered to be “slower digesting” than whey, and the consequential prolonged absorption can result in elevated blood amino acid levels for 6-8 hours following consumption. However, it’s important to recognise these values are based on consuming whey/casein in isolation, whereas digestion and absorption would differ in the context of a mixed meal.
If you're lactose intolerant, on a very low-calorie diet and/or have money to spare, then WPI might be the best choice for you! However, if you can tolerate lactose, don't mind an extra 10 calories in your protein scoop, and want to save money, then purchasing WPC and/or Casein is an excellent choice to support health, body comp change and performance!