Both come from milk and both are whey. The difference is how much processing they go through.
Whey concentrate
Concentrate is the less processed form. It commonly contains around 70 to 80 percent protein by weight, with the rest being small amounts of carbohydrate (including lactose) and fat. It usually costs less and has a fuller taste.
Whey isolate
Isolate is filtered further. It commonly contains around 90 percent protein or more, with very little lactose and fat. It usually costs more per gram.
Side by side
- Protein by weight: concentrate about 70 to 80 percent; isolate about 90 percent or more.
- Lactose: concentrate has more; isolate has less.
- Price: concentrate is usually cheaper.
- Best for: concentrate suits most people on a budget; isolate suits people who want less lactose, fat and carbohydrate per scoop.
Is isolate worth the extra cost?
Only if the lower lactose or slightly higher protein per scoop matters to you. For most people, a concentrate that fits the budget gives the same protein.
How to check
Read the label. Look at grams of protein per serving and the serving size, then work out the price per gram of protein. Neither type is lactose-free by definition, so check the label if you are lactose intolerant.
General information, not medical advice. Talk to a doctor or registered dietitian if you have a health condition.