When you go to your typical supplement store, you have 4 main protein supplements available to purchase:
1. A whey protein
2. A casein protein
3. A egg protein
4. A vegetable protein such as soy, hemp, brown rice, gemma pea, or alfalfa
Out of all the protein choices available, the gold stand is whey protein. It has the highest bioavailability and best amino acid profile. The problem with vegetable proteins like pea protein is that they have a very low biological value and poor amino acid profile.
There are two main types of whey protein available: a whey protein isolate and a whey protein concentrate. The problem with a whey protein concentrate is that it will contain a few grams of lactose (the milk sugar naturally occurring in dairy products) per serving. The majority of adult humans have a lactose sensitivity which can cause GI issues like gas, bloating and diarrhea. A whey protein isolate on the other hand is essentially pure protein and will have only trace amounts of lactose.
When purchasing a whey protein isolate you want to see nothing in the ingredients list besides whey protein isolate, natural flavours, a natural calorie free sweetener like stevia and maybe some salt, cocoa powder and soy lecithin.
I personally use the whey protein powder isolation from n2bm.com. A 30g scoop has 26g protein, 1g carbs and 0g fat.