There are many debates on why whey isolate is preferential to concentrate and we recently had a lengthy topic on MT discussing this. I have consolidated much of this debate in this article. Isolate does take longer to produce, has less fat and a higher level of protein, but does this justify the price?
The main differences are
1) Whey Protein Isolate has been processed for longer. Dairy whey goes through a series of ceramic filtration units which selectively remove fat, lactose and damaged proteins. The longer the process is continued the higher the protein and lower the fat and lactose; eventually leading to whey protein isolate. It takes a lot longer than making whey concentrate and is therefore more expensive.
2) There is very little difference in Biological Value (BV). BV is a protein scoring system used to determine the actual amount of a given protein that will be used by the body. It measures urinary and faecal losses of nitrogen when the test protein is fed to human beings. To determine the actual BV of the protein the results are then derived using this formula:
BV = (Nitrogen retained ¸ Nitrogen absorbed) x 100
This method is superior to Chemical Scoring (CS) because it is in vivo (in the body). CS looks at the overall amino acid profile of a given protein and compares with the 'standard' egg protein. If the profile of the test protein is 50% of that found in egg then the test protein gets a rating of 50.
You may have noticed that some claim whey has a BV of 159. However, the CS of whey is 159% better than egg, i.e. the CS of whey is 159, NOT the BV! Whey protein has a BV of 104.
3) The reason why manufacturers originally made whey isolate was for people who are lactose intolerant and people wanting a completely fat free product. Also whey isolates contain smaller amounts of certain minerals; hence isolates have a very 'clean' taste.
4) Composition of isolate and concentrate are nearly identical. They both contain similar amounts of branch chain aminos and similar amounts of protein fractions.
5) Both concentrate and isolate are absorbed at almost the same rate. The only time this changes is if the protein has been hydrolysed (see Issue 13).
6) Price! A whey protein isolate is typically about 50% more expensive than a concentrate. It may be the better protein, but you are paying for it!
As a protein source, whey concentrate does the job very well. In the grand scheme of things, does having the protein being absorbed very slightly quicker or having a few mg more of one amino acid really make that much different compared to having a balanced, healthy diet and putting a lot of effort in the right places in your workout? The following analogy was posted by a member: using whey isolate is like filling a family car with Formula 1 type petrol - it won't improve the performance of it. Use the money saved to buy some good quality food.
Think of isolate as a protein that has been filtered or cleaned a bit more. But does it really matter? People are getting 'whey' to concerned with science!