Upvote:3
The official rule for dairy products (which whey protein is) is that you can bring 20kg, valued at $20 or less, and of course you must declare it.
I wasn't able to discover what happens if you bring something valued at over $20, though my strong suspicion is that you may have to pay a duty and/or taxes on it.
In practice what may happen is that the customs officer will see it's canned goods from the United States and ignore it.