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Is there casein in whey protein isolate?

No, whey protein isolate does not contain casein. Whey protein isolate is a highly purified form of whey protein, which is one of the two major proteins found in milk, the other being casein. During the production of whey protein, the casein is separated and removed, leaving primarily whey protein.

Whey protein isolate is processed to remove almost all fat and lactose, and it typically contains at least 90% protein by weight. This high level of processing not only increases the protein content but also ensures that almost all other non-protein components, including casein, are eliminated1. The purpose of producing whey isolate is to provide a high concentration of protein with minimal impurities, which is particularly beneficial for those who are lactose intolerant or have allergies to other milk proteins like casein2.

For those who are specifically looking to avoid casein due to allergies or dietary preferences, whey protein isolate is an excellent choice. However, if you are allergic to milk proteins in general, it is important to proceed with caution, as some individuals who are allergic to casein may also react to traces of other milk proteins that might be present in whey products3.


  1. Smithers, G. W. (2008). Whey and whey proteins—From 'gutter-to-gold'. International Dairy Journal, 18(7), 695-704.
  2. Hoffman, J. R., & Falvo, M. J. (2004). Protein – Which is Best? Journal of Sports Science and Medicine, 3(3), 118-130.
  3. Vandenplas, Y., & Hauser, B. (2014). An updated review on the basics of whey protein and its clinical applications. Current Gastroenterology Reports, 16(4), 383.
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