As far as protein goes, any high-quality complete protein is a great foundation for muscle gain, fat loss, and improved recovery.
But, if you're looking for more than just the basics, combining a couple of different sources of protein might help give your body an additional boost.
If you dig into the research about protein, studies suggest that a special combination of whey and casein protein might be the ultimate mix for optimal results.
In fact, when compared to carbs, whey protein, and even a mix of whey protein and amino acids, the blend of whey protein and casein had the greatest benefits.
If you want to add casein to your diet, it's important to understand why this protein is oftentimes overlooked and might give your body exactly what it needs when combined with whey.
What is Casein Protein?
Casein protein comprises 80 percent of all milk protein, with the remaining 20% being whey protein. Casein is a slow-releasing protein that has been shown to improve muscle growth, among other health benefits.
Casein is a complete animal protein, meaning it contains all the essential amino acids your body needs to function well, as well as important minerals such as calcium and phosphorus (source).
While casein is found in the milk of different animals, we mainly consume the one derived from cow’s milk. One cup of milk contains approximately 7 grams of protein, the majority of which is from casein. Comparatively, cottage cheese contains around 23g of protein per cup, making dairy products a great source of casein (source).
Casein vs. Whey
Casein and whey have different chemical profiles, and they are extracted from milk in different ways. As milk is heated and enriched with different enzymes in the cheese-making process, the casein coagulates and forms curds that are made into cheese or added into dairy products, while whey separates into a liquid that can be washed, dried, and made into a powder.
To put it in simple terms: casein is the solid milk extract, and whey is the liquid part.
Although they are both complete proteins, casein and whey have different amino acids profiles. Whey protein contains more branched-chain amino acids (BCAAs), namely leucine, isoleucine, and valine. Leucine, in particular, has been found to boost muscle protein synthesis.
Essential amino acids aren’t produced by the body, and therefore, especially as an athlete, you do need to make sure to meet your daily EAAs requirements in the form of complete proteins. However, although whey protein has more of some EAAs, the main difference between casein and whey is in the rate of their absorption.
While whey protein is ingested rapidly, casein has an ability to form a gel or a clot in the stomach, ensuring a sustained, slow release of EAAs, usually lasting several hours.
Comparatively, studies show that whey protein increases leucine in the plasma almost immediately post-consumption. Its ingestion stimulates protein synthesis by 68%, while protein synthesis after casein ingestion is at 31%.
It appears that whey consumption is more beneficial during or before workouts, as it stimulates higher muscle protein synthesis, but this study also showed that 7 hours post-ingestion, casein had actually had a greater effect on EAAs levels in the blood.
The slow-releasing casein can, therefore, be used before bed, as a long-acting muscle growth stimulant, while whey protein has more immediate benefits.
What are the Benefits of Casein Protein?
Complete proteins such as casein help the body absorb nutrients and vitamins, and they help and stimulate many important physiological functions.
Casein has relatively high levels of all EEAs, with leucine at 8.3g. Amino acids are incredibly beneficial in human metabolism as they provide boost protein synthesis, reduce protein catabolism (the breakdown of proteins), and enable muscle-building.
Dairy products, especially yogurts and cottage cheese, contain high levels of casein, so eating these foods is a good way to keep your protein intake high and within daily recommendations. However, if you’re looking to go intake more than the average recommended amounts, as many athletes do, protein dietary supplements are a good way to go.
Due to its high leucine content, casein is extremely useful for long-term muscle building. What’s more, when ingested at night, it supports recovery and prevents protein and muscle breakdown.
Researchers found that casein supplementation can lead to improved muscle strength and an increase in lean tissue. Casein has also been demonstrated to aid in fat loss, along with increasing lean gains.
In terms of weight loss, casein will boost your energy expenditure (metabolism) and increase your base metabolic rate while improving satiety and making you feel more full and less prone to food binges.
Not only will casein help you lose weight, improve strength, and build muscle, but the bioactive peptides contained in casein could have great additional health benefits.
One study examined the effects of bioactive peptides and found that they have anti-microbial, immune-modulatory, and antioxidant benefits which could play a role in the prevention of disease, high blood pressure, and osteoporosis.
Are There any Side Effects of Casein Protein?
Casein protein is generally safe to consume for healthy individuals. Some people may have a casein allergy or lactose intolerance, in which case, any foods or dietary supplements need to be carefully examined for ingredients. While casein and whey protein powders generally don’t contain any lactose, they could still have trace amounts.
Healthy individuals have no negative changes in kidney function tests while following high protein diets.
What is Micellar Casein?
Micellar casein is the purest form of casein there is. In milk, casein is contained within micelles, essentially solid particles floating in liquid.
Remember how we mentioned that casein takes a while to release amino acids? It’s because it’s found in these micelles, which have the ability to form a gel or a clot in the stomach and supply long-acting nutritional benefits.
What’s the Difference Between Micellar Casein and Casein?
Micellar casein is the by-product of cheese-making and is the least-processed version of casein. It’s the complete casein protein featuring all five caseins: alpha, beta, gamma, delta, and kappa. It's made by separating the casein protein from whey, fat, and lactose in milk.
Other casein supplements, such as calcium caseinate and hydrolyzed casein are made through different chemical processes.
Micellar casein is the slowest form of casein when it comes to digestion, and it holds long-acting nutritional benefits.
Is Micellar Casein Safe?
As mentioned before, casein in all its forms is generally safe for human consumption. However, if you’re allergic to casein (i.e. milk proteins), you’ll also be allergic to micellar casein.
The Verdict: When Should You Use Casein or Micellar Casein?
Casein protein has numerous health benefits, and it can boost performance and protein synthesis for athletes. In the sea of protein supplements, casein stands out because it’s a complete protein featuring all the necessary essential amino acids.
But, is there a need to include as your preferred protein supplement? That largely depends on your goals.
It makes sense to supplement whey protein, as it comprises only 20% of milk proteins. But if you eat enough milk, cheese, or yogurt, you could already be getting all the casein you need.
In general, whey protein is the preferred dietary supplement for many athletes, as it’s rapidly ingested and boosts muscle repair and building within hours. Hydrolyzed caseinate has similar effects, but if you want fast absorption, whey protein is still the better choice.
The true benefits of casein, and in particular micellar casein, lie in their slow-releasing activity and fat loss properties.
If consumed at night, micellar casein can provide a slow release of amino acids during the time you’re fasting (i.e. sleeping). In this way, casein helps long-term muscle building, which is great for anyone who is dedicated to training, and it prevents the breakdown of protein, thus aiding recovery.
You can combine the rapidly ingested whey during and post-workouts, but casein will help you maintain and steadily increase muscle mass.