Whey and casein proteins are similar in many ways, largely due to the fact they're both derived from cow's milk. However, there are some distinct differences between the two protein sources that may make one a better choice for you, depending on your day's activities. Be sure to talk to your doctor before taking any type of nutritional supplement.
Composition
Whey protein is a byproduct of the cheese-making process. About 20 percent of the protein in cow's milk is whey protein. The other 80 percent is casein protein. According to Eric Satterwhite of Bodybuilding.com, whey and casein protein have basically the same amino acid profile. Amino acids are the building blocks of protein, and since both whey and casein are derived from the same dietary source, the amino acids contained in each are very similar.
Absorption
The primary difference between whey and soy protein is in their respective absorption rates. Whey protein is quickly absorbed in your body, so the amino acids begin the muscle-building/repairing process relatively quickly. According to Bodybuilding.com, whey protein enters your body and causes peak levels of amino acids in your bloodstream within 20 to 40 minutes. Casein protein absorbs much slower; it may take three to four hours for the protein synthesis process to be completed.
Which Is Better?
The fact is that there's not a clear-cut winner. A 2004 study published in the "Medicine & Science in Sports & Exercise" journal showed that consuming whey or casein protein supplements leads to similar results in terms of muscle gains and muscle protein synthesis. This is true even though each offered different patterns in terms of blood amino acid responses, which is largely due to the absorption rate of each. A fast-acting protein, such as whey, may be ideal for post-workout drinks where protein is needed quickly, while a slow-absorbing protein like casein may be better for a pre-bedtime snack where a slower-digesting protein is ideal.
How Much?
No matter which type or combination of the two proteins, you choose to take, it's important not to exceed the recommended dietary allowance of protein (RDA). The RDA for adults is 10 to 35 percent of your total daily caloric intake. Sedentary people should stick to the lower end of the scale, while active people should consume more protein to support muscle growth and prevent loss of lean muscle mass. According to the University of Illinois McKinley Health Center, a 20 to 25 g whey protein shake per day is ideal for the average person while 40 to 50 g each day is beneficial for athletes.
References
- Bodybuilding.com; Casein vs. Whey? Benefits and Disadvantages Everyone Should Know!; Jamie Hale
- Bodybuilding.com; Should I Take Whey or Casein?; Eric Satterwhite
- "Medical & Science in Sports & Exercise"; Ingestion of Casein and Whey Proteins Result in Muscle Anabolism after Resistance Exercise.; Tipton KD, et al.; Dec. 2004
- University of Illinois McKinley Health Center: Creatine and Whey Protein Supplements
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