Milk really does do a body good. It’s high in calcium, vitamin D and potassium. And it’s also rich in a beneficial protein called casein (pronounced ”KAY-seen“).
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If you’re a regular dairy milk drinker, you’re already getting some benefits of casein. But you may want to consider adding more casein to your diet. Athletes and bodybuilders have been using casein protein powder for years. But the benefits of casein aren’t just for pro sports players.
“Protein is a vital part of any balanced diet,” says registered dietitian Elyse Homan, RD, LD. “But different proteins have different effects. Understanding how each protein works is beneficial, especially if you’re supplementing with it.”
What is casein?
Casein is the main protein found in dairy milk, which includes the milk from:
Casein makes up about 80% of the protein found in milk. The other 20% comes from whey protein.
“When you think of curds and whey,” Homan says, “the solid part is casein protein, and the liquid part is whey protein.”
Getting enough protein is important because protein has many jobs. It has to:
- Carry out chemical reactions (like digestion).
- Help your tissues and organs change and grow as needed.
- Protect your body from viruses and bacteria.
- Support your body’s movement by providing cell structure.
Casein vs. whey
Casein and whey have a lot in common. They’re both:
- Animal-based proteins.
- Complete proteins — they contain all the amino acids your body needs.
- Excellent sources of calcium.
- Found in dairy milk.
The main difference is that casein is a slower-digesting protein than whey. “Casein forms a gel-like substance in your stomach,” Homan explains. “It releases more slowly than other proteins and takes longer for your body to absorb.”
Casein protein benefits
Getting the recommended daily amount of protein helps you stay healthy. But casein’s slow absorption also gives it some added advantages. The health benefits of casein include:
1. Gives you all the essential amino acids
Amino acids combine to form proteins. There are 20 amino acids that your body needs to work correctly, and they join in various ways to create different proteins.
Your body makes some of the amino acids it needs, but there are nine essential amino acids that your body can’t produce — you must get them from food. Casein is a complete protein and has all nine essential amino acids.
2. Reduces muscle breakdown
Your cells rely on regular “feedings” of amino acids to continually make proteins. When you go without eating overnight or during an extended fast, your cells may not get the needed amino acids. As a result, they look for those amino acids elsewhere and break down your body’s muscles to get them.
As a slow-release protein, casein provides your cells with the amino acids they need over a long period. The slow absorption consistently feeds your cells with amino acids, allowing muscles to recover instead of breaking down.
3. Promotes muscle growth
Casein contains a high amount of leucine, an amino acid that regulates metabolism (how your body changes food into energy) and helps build and repair muscles. If you don’t typically consume a lot of protein, adding more leucine-heavy protein to your diet (like casein) can help your muscles grow when also engaging in regular exercise.
4. Provides a good source of calcium
The casein in milk is a good source of calcium, which is essential for teeth and bone health. Not getting enough calcium can lead to a loss of bone mass and increase your risk of osteoporosis (a disease that weakens your bones).
Casein protein powder may contain up to 50% of your recommended calcium intake — but always check the label to make sure that the protein powder is a good source of calcium.
How casein protein powder can help
Casein protein’s general health benefits are good for everyone. But using casein protein powder ensures you’ll get a more significant amount of casein each day. Talk to your healthcare provider about taking casein protein powder for:
A high-protein diet can help you shed excess pounds and maintain a healthy weight. Protein can help you feel full and improve your satisfaction after the meal.
Different types of proteins affect you differently after you eat them:
- Whey protein, which you absorb quickly, makes you feel full immediately after ingesting it.
- Casein’s slow rate of release helps you feel fuller longer.
One study found that participants who consumed casein protein powder before a meal ate less at that meal than people who had whey protein, egg albumin (made from egg whites) or water alone.
“Our bodies only absorb so much protein at one time,” Homan clarifies. “About 30 grams of protein per meal is a good amount to consume. If you plan to have more than one serving of casein powder daily, space it out.” It may help you stave off cravings and decrease snacking between meals, too.
Overnight muscle growth and recovery
Bodybuilders and athletes know that protein is key for building muscle. But keeping your body’s protein levels up overnight can be challenging. That is, unless you ingest casein immediately before going to sleep.
Research shows that consuming casein protein before bed balances your body’s protein level throughout the night. When your protein level stays consistent, muscles can continue to grow and recover — even though you’re not eating.
What to consider before taking casein
For most people, casein doesn’t cause any side effects. But Homan says certain people may need to avoid or limit casein if they have a condition such as:
If you have a milk allergy, the proteins in milk trigger your immune system and cause it to overreact. People with a milk allergy are allergic to casein, whey or both.
A severe allergy can cause anaphylaxis. More mild symptoms of a milk allergy include:
“Casein allergies are not as common in adults as in children, but they do exist,” notes Homan. If you suspect you have a milk allergy, an allergist can do a test to figure out what you’re allergic to.
Like all dairy products, casein contains the sugar lactose. If you have lactose intolerance, your small intestine can’t digest milk sugar. When you have dairy products, you may develop symptoms including:
“Casein supplements do have lower amounts of lactose,” Homan states. “If you’d like to include casein in your diet but have a lactose sensitivity, the supplement might not trigger it. Talk to your healthcare provider if you’re interested in taking a supplement.”
People with kidney disease often need to limit their protein. Too much protein can cause too much waste in your blood. If your kidneys can’t remove the waste, the buildup of toxins can lead to serious health complications.
“People with a protein restriction, such as those with kidney disease, don’t have to avoid casein,” Homan says. “But they do need to watch how much total protein they eat. Your healthcare provider can help you figure out the right amount.”
Sources of casein protein
There are two ways you can add casein to your diet:
A powdered casein supplement can help you get high amounts of it, according to Homan. The most common form of casein powder is micellar casein, or you can get a rapidly absorbing type (casein hydrolysate). One serving typically contains 24 to 27 grams of protein. Mix with water to create a protein shake, or add it to smoothies, yogurt or baked goods.
“People looking to build muscle or get more protein in their diet should talk to their healthcare provider about adding casein,” she adds. “Supplementing with casein isn’t necessary if you have a healthy, balanced diet, but it can be helpful for some people.”
The U.S. Food and Drug Administration doesn’t regulate supplements. So, it’s a good idea to look for a casein supplement that underwent third-party testing. It’s usually a sign of a higher quality product.
Casein food sources
Anyone can benefit from casein, and you and your family probably already get it from the dairy products you consume, such as:
“Adding a dairy product to your breakfast is an easy way to get some casein every day,” Homan encourages. One glass of milk has 8 grams of protein — 6.4 grams (80%) of that protein is casein. “It’s great to start your day with a good protein source.”