Whey and casein both come from milk and are both complete proteins. The main difference lies in the rate of digestion: whey is absorbed relatively quickly, whilst casein is digested slowly over several hours. They are not competitors; they complement each other. Below, you can read about where this difference comes from, when to use which, and how to choose what suits your goals and daily routine.
What is the difference between whey and casein?
Whey and casein are the two proteins found naturally in cow’s milk. The most important distinction is this: whey is digested quickly, whilst casein is digested slowly.
Milk consists of approximately 3.5% protein. Of this, roughly 80% is casein and 20% is whey. During cheese production, the whey is filtered out of the curd, whilst the casein largely remains in the milk. Both are complete proteins containing all the essential amino acids; they differ mainly in their amino acid composition, and therefore in how quickly your body processes them.
As sources of protein, they serve the same purpose. Protein contributes to a growth in muscle mass. Protein contributes to the maintenance of muscle mass. Protein contributes to the maintenance of normal bones. This applies to both whey and casein, as they are both simply forms of protein. Would you like a more in-depth look at each type? We’ve written a separate article on why whey protein is used and what it does, and on what casein is and how slow-release protein works. This article focuses solely on the comparison.
Is casein the same as the protein in quark?
Yes. Casein is the protein found naturally in quark, milk and cheese. Quark is therefore one of the richest natural sources of casein.
As around 80 per cent of the protein in milk is casein, you’ll find it in many dairy products. That’s why quark is often mentioned when the topic of casein comes up. If you want to get casein without eating quark every day, casein protein powder is a practical alternative containing the same type of protein.
Whey or casein – which is best?
Neither is ‘best’. Both are complete proteins; the choice comes down to timing, texture and personal preference, not quality.
In short: whey is absorbed quickly and is therefore a common choice around training sessions or as a quick, protein-rich snack. Casein is digested slowly over several hours and is therefore more commonly used in the evening, or as a slow-digesting protein source within a meal. Many people use them together, precisely because their digestion rates differ.
When should you take whey and when should you take casein?
The timing follows logically from the digestion rate. Take whey when you want protein quickly, and casein when you’re consuming it over a longer period.
- Whey: absorbed quickly. Handy around a training session or at a busy time when you want a protein-rich shake quickly.
- Casein: digested slowly over several hours. Commonly taken in the evening, or via a casein-rich option such as a tub of quark.
- Vegan: suitable at any time. If you’re lactose intolerant or don’t eat animal products, vegan protein powders are your alternative. There’s also a certified organic option made from pure fava beans: our Vegan Protein Organic.
The total amount of protein you need depends on your weight and how active you are. We’ll look at this in more detail in our article on how much protein you need each day.
Whey, casein and vegan protein compared
Below is a summary of the key differences: source, digestion rate, texture and typical uses.
| Characteristic | Whey | Casein | Vegan (pea, fava, soya) |
|---|---|---|---|
| Source | Milk (whey protein from the curd) | Milk (approximately 80% of milk protein) | Pulses and cereals |
| Digestion rate | Fast | Slow, over several hours | Medium (faster than casein, slower than whey) |
| Naturally found in | Rare in the daily diet, mainly as a supplement | Quark, milk, cheese | Pulses, beans, nuts |
| Texture in a shake | Thin and light | Creamy and thick (suitable for protein fluff) | Varies depending on the source |
| Suitable for those with lactose intolerance | No | No | Yes |
| Suitable for vegans | No | No | Yes |
| Commonly used | Around training | In the evening or as a slow-digesting source of protein | At any time of day |
How do you use casein powder?
You use casein powder just like whey powder: mix a scoop with water or milk to make a shake. Due to the protein structure, a casein shake is creamier and thicker than a whey shake.
The natural option is still quark, and we prefer to get our nutrients from our daily diet. But powder is handy if you want some extra protein without having to eat quark every day. A popular way to use casein is in ‘protein fluff’: pulse 125 grams of frozen fruit in a food processor until powdery, add 20 grams of casein powder and 100 ml of milk, and whisk with a hand mixer for about 3 minutes until light and creamy. Casein works well for this because it whips up light and fluffy.
Frequently asked questions
Is whey or casein better for muscle building?
Neither is ‘better’. They are both complete protein sources. Protein contributes to a growth in muscle mass. Protein contributes to the maintenance of muscle mass. The difference lies in digestion rate and timing of consumption, not in quality.
Can you combine whey and casein?
Yes. Because they are digested at different rates, they complement each other well. A common combination is whey around your workout and casein later in the day or in the evening.
Does casein contain lactose?
Whey and casein are both milk proteins, so they are not suitable for people with lactose intolerance or those on a vegan diet. In that case, opt for a vegan protein powder.
Is casein powder the same as quark?
Casein is the protein found in quark, so in terms of protein type, they are the same. Powder is purer and easier to measure out; quark also contains moisture, fat and other nutrients.
Stock up on whey and casein at home
Would you like to have both a fast-acting and a slow-release protein source at home? Our organic casein (plain) is a casein powder without any unnecessary additives, and you’ll find its fast-acting counterpart in the whey range. Together, they cover your entire day, from around your workout right through to the evening.
