[quote]akumaslair wrote:
hi everyone,
apologies if this has been done before but i couldn’t find it through the search function
now I know the basics of the differences between WPI and WPC.
WPI being higher in protein usually 90%+, WPC being anything from 40%-90%, with the WPI being quicker absorbed.
now, a few knowledgable people have told me, that a cheap crappy WPI is far inferior then a expensive WPI, even if the % is the same. I find this a bit difficult to understand, I would have thought protein is like energy or temperature, its just a figure in respect to ZERO with no quality. eg 100 Degrees is 100 Degress.
Currently, I am taking a rather expensive WPI x 30g twice a day, once after training and once in the evening.
I am having 2 problems, I am running out of money, so I am thinking of switching to a cheaper WPI for after training.
I ahve also just heard a few people say, for the protein shake you take during the day when you aren’t training, becuase it doesnt need to be absorbed quickly. cheaper WPI is fine or WPC is actually better!!!
can someone please give me a few pointers…[/quote]
There are differences between grades of protein other than the amount of protein contained.
For instance, there are various ways to filter protein to achieve isolate status : there is cross-flow microfiltration versus ion exchange. Ion exchange seperates components based on their electrical charge, and from what I’ve read the process is generally harsher on the fragile immunoglobulins present in the whey protein. These are immune proteins which can bolster immune system. I have read that ion exchange denatures these, rendering them inactive.
Cross flow microfiltration, on the other hand, suppposedly does not do this, and is supposedly a superior filtering method to achieve whey isolate.
Now, whey concentrate, even though it is less than 90% protein by volume, also retains the immunoglobulin content, so a blend of whey isolate and whey concentrate is good if you don’t know how your isolate is filtered.
Both whey isolate and whey concentrate are slower digesting than hydrolyzed whey protein.
I personally think whey of any sort during the day is too fast to be an ideal single source of protein; it should be combined with some slower digesting protein for optimal benefit. Use whey by itself upon waking and peri-workout.
Of course, obsessing over the details such as this might increase your cortisol levels to negate any benefit gained from optimizing your protein intake 
Buy Grow! Whey here - contains both isolate and concentrate, you know its good quality, and its very, very affordable - plus, you support this website.