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After whey protein, casein is one of the most popular on the market. It is especially popular among strength athletes, who use it most often before bedtime. That is why it has earned the nickname of the night protein. It helps with meeting their daily intake of protein, which is needed for both muscle growth and protection. However, it also promises other benefits such as promoting recovery or weight loss. In today’s article, in addition to the effects of casein, you’ll learn how it differs from whey protein and how to make the most of its effects.
In this article you will read about the effect of casein on these specific areas:
What is casein?
You can put the fear that casein is somehow an artificial substance behind you. Almost all of you consume it in your diet and you might not even know about it? Casein is a natural part of milk, which makes up approximately 80% of all proteins, with whey protein making up the remaining 20%. Therefore, you normally consume both types of protein through dairy products. How does casein from milk get to the form in which it is found in supplements?
As we have already said, the raw ingredient for the production of casein protein is milk. This is first heated and acid and enzymes are added to it to cause the milk to curdle. This separates the solid casein from the liquid whey, which then undergoes various filtration processes before it becomes whey protein itself. As a result, beware of confusion between the terms whey and whey protein. Of interest to us, however, is casein. This is also filtered, dried and further processed to produce a pure powder. Depending on the manufacturer, flavourings and other substances can then be added to the final product to ensure the best possible taste and flavour characteristics. 
The process of separating casein from whey can be seen, for example, in unblended yoghurt. The separated liquid on the surface is whey containing whey protein, which is soluble in water. In contrast, casein is insoluble in water. It takes the form of tiny spherical formations called micelles. 
When casein is mixed with acids or enzymes, it acquires a gel-like texture. This is why it is used to make cheese or cottage cheese and is also used as a thickener or stabiliser in food. It also reacts similarly in your stomach, where it is affected by stomach acids. It begins to ‘gel’, which then leads to a slower digestion process. Gradually it enters the small intestine, where it slowly releases peptides and amino acids. Depending on the portion size, this digestion process can take up to 7 hours (the rate of absorption of amino acids is approximately 6.1 g/h), which is almost twice as long as whey protein. This is why casein is often called a slow protein and whey a rapid protein. [1-2, 7, 16]
What is the nutritional profile of casein?
From a nutritional point of view, casein is one of the highest quality sources of protein, containing approximately 75-80%. When you break it down, you get all 9 essential amino acids that your body can’t produce on its own. As a result, it has the highest possible score (1) for the quality of the amino acids it contains (PDCAAS – Protein Digestibility-Corrected Amino Acid Score). When you look at how it performs in a more up-to-date method (DIAAS – Digestible Indispensable Amino Acid Score) comparing the amino acid content and digestibility of different protein sources, you will see that it performs even slightly better than whey protein. 
What is the difference between casein and caseinate?
There’s no casein like casein. You may have come across calcium, sodium or potassium caseinate on the packaging of a food or supplement. These forms are created by chemically processing casein, and the proteins contained can be degraded, which then lose their usefulness in the body. For this reason, it is recommended to supplement your diet with higher quality forms such as micellar or hydrolysed casein. 
Forms of casein
- Caseinate – produced by an older method, namely enzymatic processing of casein. It has poorer digestibility and lower utilisation of the ingested protein than newer forms.
- Micellar casein – a slowly absorbed protein produced by the microfiltration of milk in which casein is naturally present in the form of micelles. Due to this complex structure, casein proteins take longer to digest than whey protein, and the amino acids are released into the bloodstream gradually. It is mainly used as a night protein.
- Hydrolysed casein – the newest form of casein that has undergone a hydrolysis process in which proteins are broken down into more rapidly absorbed peptides. This makes it easier to digest and the necessary amino acids reach the muscles sooner. This is why this protein is also suitable for use around training. However, there are relatively few products with hydrolysed protein on the sports nutrition market and some may also be bothered by the bitter taste that is produced during hydrolysis. 
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The 6 most well-known effects of casein
1. Growth of muscle mass
Trying to gain muscle mass? In that case, you probably already know that in addition to a quality workout, your body also needs plenty of building materials in the form of amino acids. You get these through protein from your diet and supplements. This will support anabolic processes, which should outweigh catabolic ones (muscle breakdown) during the muscle-building period.
According to studies, casein is very effective in this respect. Thanks to its slower absorption, it supplies the body with amino acids for a longer period of time, and the formation of muscle protein (MPS – Muscle Protein Synthesis) can take up to 6 hours, according to some studies. In the case of whey protein, this time was 3.5 hours. However, it may be even more important as a night protein. Even scientific studies have shown that taking casein before going to bed led to the promotion of anabolic processes associated with muscle growth during sleep. 
It’s no wonder that the intake of casein before going to bed is one of the basic rules of muscle building. It has been followed by bodybuilders since the golden era of bodybuilding, who traditionally consumed it in the form of cottage cheese. Furthermore, it is one of the richest sources of this protein, but nowadays, it is often replaced by more concentrated supplements that don’t require you to keep your fridge stocked with cottage cheese.
You can’t forget that in order to support muscle growth it is also important to meet the total daily protein intake, which for strength athletes should generally be in the range of 1.4-2 g/kg body weight. 
If you are in the process of gaining muscle mass and are wondering how best to support it through diet and training, read these practical tips in our article 10 Nutrition and Training Tips for Maximum Muscle Growth.
2. Maintaining muscle mass and strength
If you’re trying to lose fat while maintaining maximum muscle, casein can help. With a low energy intake from your diet, it’s common for your body to start burning more or less muscle in addition to fat. This can be partially prevented if you have an optimal daily protein intake. Casein will then help especially with the continuous supply of amino acids during sleep or at any other time when we go longer without eating. This way, the body won’t have to reach into muscle tissue for its own stores of amino acids during prolonged fasting.
The anti-catabolic effects of casein have been tested in a number of studies. One of them examined the effect of protein intake on overall fat loss and muscle mass gain. Participants were in a caloric deficit, had a higher protein intake (1.5 g per kg of body weight), and ingested either hydrolysed casein or hydrolysed whey protein. In addition, they strength trained. The experts observed similar fat loss in both groups after 12 weeks. However, muscle gain was slightly higher with casein (+4 kg ± 1.4 kg) than with whey protein (+2 kg ± 0.7 kg). However, the difference in favour of casein was even more pronounced in terms of increase in chest, shoulder and leg strength. 
Casein can help you maintain your hard-earned muscle mass and strength even whilst you’re losing weight.
Check out what else can help you lose weight healthily in our article Tips to Help You Lose Weight and Get Fit.
3. Post workout regeneration
Quality recovery is the key to success for every athlete. Not at the gym, but in the time you rest, all the magic happens. This is because training-damaged muscle tissue is repaired, new muscle cells are formed and energy sources are replenished. In order for everything to work as it should, we need to rest enough and replenish protein and other necessary nutrients.
In the immediate post-workout period, it is effective to boost recovery with a quick protein in the form of a whey protein drink. However, if you do not get to eat solid food for a longer period of time, casein also has a place in a post-workout protein drink. This also applies if you want to support anabolic processes during sleep. The latter has also been proven in studies to optimise the formation of new muscle cells, reduce muscle breakdown and achieve a positive protein metabolism where anabolic processes outweigh catabolic ones.
In terms of recovery, however, studies have shown that ingesting 40-48 g of casein approximately thirty minutes before going to bed can alleviate muscle damage caused by training and reduce post-exercise muscle soreness (DOMS – Delayed Onset Muscle Soreness). Putting these properties together, you can’t ignore the promising potential of casein protein and its effect on recovery. 
For more ways to make recovery more effective, read our article How to Boost Recovery with a Massage Gun and Other Aids?
4. Feelings of satiety
You already know that casein is digested more slowly than other sources of protein, so it’s no surprise that scientists have decided to investigate its effect on satiety. Protein generally has a greater satiating effect than carbohydrates and fats. Thus, when you eat a meal with a higher content of this nutrient, the feeling of fullness lasts longer than if you eat an equally calorie-dense meal without protein. 
According to experts, casein protein is a big part of why dairy products fill us up so rapidly and for longer. However, there are several mechanisms behind this and it is not yet clear which plays the biggest role. Activation of certain receptors in the stomach appears to play a role. It breaks down casein into simpler peptides with a bitter taste. This is then picked up by special bitter taste receptors in the cells, which stimulate the production of stomach acid, the hormone serotonin, and slow down gastric emptying. All of this can ultimately lead to a prolonged feeling of satiety. 
When you feel fuller for longer, you reduce the risk of overeating and can better control your appetite. Therefore, maintaining a healthy body weight.
In case you are struggling with an uncontrollable sweet tooth in particular and are wondering what could help, here are some of the most important things you can learn from our article 15 Steps to Rid Yourself of Sweet Cravings.
5. Weight loss and maintaining a healthy weight
At a time when you are reducing your food portions and doing everything you can to lose centimetres on your waistline, the properties of casein become even more important. As you already know, it can help you maintain muscle mass, which is often lost along with fat during weight loss. The second benefit is the enhancement of satiety and also better control over your food intake, which is one of the main prerequisites for successful weight loss.
In addition, casein will help you achieve optimal protein intake, which is worth taking more of during weight loss for muscle protection and satiation. Ideally between 1.2-2.4 g of protein per kg of body weight, depending on how physically active you are. Athletes, especially strength athletes, are generally advised to keep their intake near the upper end of this range, around 2 g of protein per kg/bodyweight. 
How to eat while losing weight or gaining muscle?
- To learn more about how much protein to consume based on your goal or stage in life, read our article How Much Protein to Consume for Muscle Growth, Weight Loss, Endurance Performance or Pregnancy?
- The Online energy intake and macronutrient calculator will help you set your energy intake, protein, carbohydrates and fats.
- In case you’re wondering what else is important when losing weight, read our article Simple Weight Loss Basics: You’ll Be Surprised At What’s Really Important.
- For more dietary supplements that facilitate weight loss, check out our article Dietary Supplements for Weight Loss: Which Help Burn Fat or Satiate?
6. Other possible effects of casein
- Antibacterial effects: studies have also found that milk proteins, including casein, can inhibit the effects of harmful bacteria such as Escherichia coli. As a result, they can support our body’s natural immune functions. 
- Antioxidant effects: some milk peptides may also be involved in protecting cells from oxidative stress. 
- Support immune functions: casein contains bioactive peptides that are associated with the activation and growth of white blood cells (lymphocytes) and macrophages, the main components of cellular immunity. 
- Lowering triglyceride levels: in a study, it found that by adding casein to a fat-rich meal led to a reduction in postprandial (after-meal) triglyceride levels, which may have a positive effect on the cardiovascular system. 
The best sources of casein
As we have already said, casein makes up 80% of milk protein. It has a solid consistency, so it’s no surprise that the richest sources are cheese or cottage cheese. However, casein protein is also found in milk, yogurt and other fermented dairy products. Outside of regular foods, this protein can also be found in supplements in the form of micellar casein, complex night proteins and other multi-ingredient products.
What is the difference between casein and whey protein?
These proteins differ in chemical structure and properties, which then determine in which situations they are used. In general, whey protein is preferable after a workout or during the day when you want to replenish protein quickly. However, when you know you won’t be eating for an extended period of time and you want to supply your muscles with amino acids for several hours, go for casein alone or in combination with whey protein. The same goes for bedtime. The best way to do this is to combine whey protein and casein in your supplementation. [12-13, 16]
|Slow (up to 7 hours)
|Rapid (up to 3.5 hours)
|Rate of absorption of amino acids from the intestine into the blood
|Content of l-leucine (the amino acid with the greatest anabolic potential
|Before going to bed, during a longer fasting period, after a workout
|Before and after workouts, during the day
|Impact on appetite
|Satiety that lasts longer (up to 180 minutes after consumption)
|Rapid satiety (30-60 minutes after consumption)
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Recommended casein intake
The appropriate daily dose of casein depends on your goals to determine your ideal daily protein intake. Protein from food and supplements can help you achieve this.
How to use casein?
- Take 1-2 times a day in a dose of 20-40 g according to your daily protein intake. 
- It is useful before bedtime or at any time during the day or if you go several hours without eating. But you can also use it after a workout when it can take a longer period of time (2 hours or more) to eat a solid, complex meal.
- Choose micellar or hydrolysed casein.
- In addition to single-ingredient products, you can also find micellar casein in more complex night proteins.
- Consume the supplement alone mixed in a shaker with water or milk or add it to porridge or smoothies.
- Follow the manufacturer’s instructions for recommended use.
If you’re also wondering which foods can help you meet your daily protein intake, see our article Foods That Easily Add Protein to Your Diet.
What should you combine casein with?
- For maximum anabolic potential with leucine, BCAA or EAA.
- To support regeneration with maltodextrin or other carbohydrates.
- To create a complex protein drink with proteins with different absorption rates, mix with whey protein.
Side effects of casein
Since casein is a natural part of our diet in the form of cheese and other dairy products, it is considered safe. As long as you are healthy, you do not have to worry about side effects if you follow the recommended dosage. 
For whom is casein not suitable?
- If you have kidney or liver disease, consult your doctor about the suitability of taking casein.
- It is not recommended for individuals with casein allergy or lactose intolerance. For these, plant proteins may be more suitable.
You can learn more about protein in our other articles:
- Our article How to Select the Right Protein for Weight Loss or Muscle Growth can also help you decide which protein to go for.
- If you want to learn more about whey protein, read our article Which Protein to Choose? Whey Concentrate, Isolate or Hydrolysate?
- In case you want to partially or completely replace animal proteins with plant proteins, our article How to Select the Best Plant Protein? will help you with your choice.
- You can read more about the importance of protein for women in our article How Does Protein Change the Female Body and Help You Lose Weight?
- If you are still hesitating whether it is better to combine protein with water or milk, it will become clear after reading our article Is it Better to Drink Protein with Water or Milk?
What should you remember?
Casein is an effective dietary supplement for anyone who wants to maximally support muscle gain or post-workout regeneration. Thanks to the fact that it is digested slowly, it satiates for several hours, which can also come in handy during weight loss. It is especially suitable before bedtime or when you can’t get to a solid meal for several hours. In supplement form, it is ideal to choose micellar or hydrolysed casein and take it 1-2 times a day in quantities of 20-40 g.
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