Casein Protein

Casein is a form of protein that helps prevent muscle breakdown, increase fullness and improve body composition. Alongside whey, casein protein is extracted from milk (both cow’s milk and human milk contain differing amounts of casein) (1).

Casein protein on the other hand is much slower when it comes to digestion, due to it forming a “clot” in the stomach and drip feeding nutrients and amino acids into the blood stream over a longer period (2, 3).

Best Casein

1. Bulk Supplements Casein

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Bulk Supplements offer 100% pure casein protein powder with no other ingredients, fillers or additives.

Each supplement is tested in their in-house laboratory before distribution, ensuring that all products are safe for consumption. Their FDA-registered cGMP manufacturing and distribution facility has a staff of over 60 full-time employees that take pride in providing excellent customer service and producing quality products for our customers. For these reasons, it’s our top pick.

2. Ascent Native Fuel Casein

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Ascent Native Fuel Casein protein is a phenomenal product, containing 25g protein per scoop and 11g of naturally occurring BCAAs. They use zero artificial ingredients and are certified gluten-free and Informed-Sport Certified.

Where Ascent really shines is quality control. Unlike most companies, they don’t buy protein from anyone else. Ascent buys Grade A milk from trusted dairy farmers and then filter the proteins in our own facilities – and they’ve have been doing this for over 30 years.

3. Naked Casein

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Naked casein has only one ingredient: 100% micellar casein protein powder. It also comes with no growth hormones, no rBGH, no rBST and no additives.

This casein protein is also cold processed, which means there is no contamination from chemical detergents (no acid or bleach), synthetic additives, or heavy metals. It’s one of the cleanest products in the marketplace.

4. Legion Athletics Casein+

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Casein+ is a naturally sweetened and flavored, made from exceptionally high-quality milk from small dairy farms in Ireland. It’s 100% micellar casein protein with no GMOs, MSG, hormones, artificial food dyes, or unwanted fillers or chemical junk.

What’s more, Casein+ tastes delicious, mixes great and is packed with essential amino acids, including leucine.

5. Rivalus Promasil Casein

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Promasil Casein protein powder contains a blend of 4 casein protein types: native micellar casein, micellar casein, partially hydrolyzed casein, and alpha-lactalbumin to maximize the release of protein into the bloodstream over hours and hours.

The advantage of extended digestion time is hours-long delivery of amino acids – an attribute that is particularly advantageous throughout the night while you sleep. All Rivalus products are free of banned substances and built-in world-class facilities.

6. Optimum Nutrition Gold Standard Casein

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Optimum Nutrition has been a leader in protein powders since they were pretty much invented, due to their superior formula. Each serving of Gold Standard Casein contains 24 grams of time-released protein, over 5 grams of BCAAs (Leucine, Isoleucine, and Valine) and nearly 5 grams of Glutamine & glutamine precursors in every scoop.

It also contains Aminogen digestive enzymes to enhance utilization.

7. MuscleTech Casein Gold

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Nitro-Tech Casein Gold is superior to other casein protein powders – more protein per scoop, fewer carbs and more servings. It delivers 24g of high-quality protein taken from multiple premium casein protein sources.

Nitro-Tech Casein Gold Smooth is a great-tasting protein powder that doesn’t pack the extra sugar and carbs you’ll see in other whey protein and casein protein powders.

8. Dymatize Elite Casein

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Dymatize elite casein provides a sustained release of muscle-building amino acids to support muscle growth and recovery. It contains 25 grams of 100% micellar casein, 5 grams of BCAAs & 2.3 grams of L-leucine per serving.

Elite Casein uses a cross-flow microfiltration processing to help preserve the natural state of casein protein’s important muscle-building properties.

9. Kaged Muscle Kasein

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Kaged Muscle Kasein is a complete protein that gives you essential amino acids to help repair and rebuild muscle during recovery. Each serving contains 25 g of ultra-premium cold-pressed micellar casein isolate for a sustained-release protein that helps prevent muscle breakdown.

Kaged Muscle Kasein is manufactured using an innovative microfiltration process that preserves the structural integrity of the protein. Each tub of Kaged Muscle Kasein has 100 percent ingredient transparency on the label so you know exactly what you’re putting into your body.

10. Six Star Elite Series Casein Protein Powder

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Six Star Elite Series casein protein powder ensures a continued flow of amino acids to your muscles with their sustained delivery formula. Each scoop serves up 24g of protein and 4.9g of BCAAs.

Six Star Casein Protein comes in a delectable triple chocolate flavor, distinguished by the Gold Medal from the American Masters of Taste.

How We Rank

The first step we took to find the best products was to see which products were 100% casein and which ones were protein blends with casein. While protein blends can have some advantages, 100% casein is what we wanted for this ranking. This is why BSN Syhtna-6, which is a blend of multiple proteins (including casein), as well as BioTrust are not found on this list.

The second thing we looked at was the formulation. Was it pure protein powder, or did it have a ton of sugar, artificial sweeteners, and undesirable additives? We preferred products with ingredient lists of less than 5 for our rankings, and ideally 1-2. This is why you’ll find Naked Casein (which only has one ingredient: casein protein), at the top of our list.

Lastly, we looked at flavoring and mixability. Casein protein can be challenging to make taste right and mix well. It often requires superior manufacturing and attention to detail in the processing. Products like Legion Casein+ and Ascent Native Fuel are ranked at the top because they go the extra mile to ensure high-quality casein mixes well.


1. Casein protein can prevent muscle breakdown. Exercising in a fasted state is generally seen as a bad idea, but it used to be promoted as a fantastic way to burn fat.

This belief was pretty much laid to rest by an article by Brad Schoenfeld where he stated that not only is there no increase in fat loss, but due to a lack of energy, the workout will potentially lead to less fat burning as performance will have dropped (4).

But people still do it, often due to training very early in the morning.

If you train in a fasted state, then your body will not have any protein stores to begin protein synthesis. This means that taking some immediately after a workout would be beneficial. A 2009 study found that taking a protein and carbohydrate meal immediately post-workout (fasted) will prevent muscle protein breakdown (5).

A combination of whey protein, casein protein, and a carbohydrate source would be perfect.

2. Casein protein can protect against muscle loss. For weight loss to occur you need to be in a calorie deficit, that is the only way that you can drop body fat. The bigger the deficit, the faster the fat loss (up to a certain point). This is why crash diets and week-long fasts can cause such incredibly fast weight loss results.

The downside of creating a big deficit is that you can actually begin to lose muscle mass (there are of course many other physiological and psychological downsides – which is why crash diets are such a poor nutritional strategy). But even a sensible diet can lead to some muscle loss, the trick is to limit this as much as possible. Studies have shown that increasing protein intake can prevent muscle loss during short-term calorie deficit diets.

A 2013 study found that consuming twice as much protein as recommended can protect fat-free mass during a short-term diet (6).

Whey protein or casein protein, or a combination of both would be perfect for this.

3. Casein protein can increases satiety. Satiety is another word for feeling full after a meal, the fuller (or more sated) you feel after a meal the less likely you are to want to eat. This means that foods that can increase satiety after a meal are better on diets. The most satiating food according to the satiety index for common foods is the boiled potato (7).

But high protein foods that are also satiating are better due to their ability to increase your metabolism and protect muscle.

Many studies have compared casein protein powder to whey and other protein powders and have found mixed results, some found casein to be more satiating while others found whey. A 2011 study compared casein, pea protein, whey, and egg albumin (protein powder) to find which was the most satiating (8).

It found that casein and pea protein were significantly more satiating than the other sources.

A 2014 study found that whey protein was more satiating than casein and also more satiating than a carbohydrate supplement (9).

This may seem a bit confusing, and it is.

There doesn’t seem to be much of a consensus on why whey and casein might/might not be more satiating than the other. Casein is slower to be absorbed and travels through the intestines at a slower rate, which makes it work like fiber and theoretically should make it more satiating. But whey may cause a different hormonal response.

A 2008 study explains it like this:

“Different proteins cause different nutrient-related responses of (an) orexigenic hormones. Protein-induced satiety coincides with a relatively high GLP-1 release, stimulated by the carbohydrate content of the diet, PYY release, while Ghrelin does not seem to be especially affected, and little information is available on CCK.” (10)

In other words, different protein sources can stimulate different hormones that deal with appetite, but at the moment science is not certain which proteins affect which hormones. On the other hand, a study in 1998 failed to find any difference between protein types and instead posited that protein intake is more important (how much protein you have) (11).

They also suggested that because you usually consume protein as part of a meal the other foods will influence satiety overall. Of course, this is clearly not the case when taking a casein or whey protein shake as they are taken in isolation. Whatever the science says, one thing is for certain – casein protein can increase satiety and is, therefore, a good supplement to take while on a diet.

4. Casein protein can help improve body composition. Due to casein protein being effective at protecting fat-free mass during a diet, and improving dieting adherence by increasing satiety, it is perhaps no surprise that casein protein can improve body composition. It is well established that reducing carbohydrates and increasing protein intake can improve body composition, and studies have demonstrated this (12).

A high protein diet can increase thermogenesis (slightly), increase satiety (as we mentioned above) and as a result improve weight loss (13).

Both whey and casein protein have been shown to do this, particularly when combined (milk protein). A 2013 study found that milk protein can improve metabolic health and reduce body fat (14).

5. Casein protein taken before bed can improve post-exercise recovery. A 2012 study looked at post-exercise recovery and casein protein (15).

The study involved 16 healthy young men who all performed a resistance workout (free weights and machines) at 8 pm after consuming a standard diet.

30 minutes before sleep (11:30 pm) they took either 40g of casein protein powder, or they took a placebo. The study measured their blood and muscles to assess how much protein synthesis occurred during sleep (7.5 hours). The study found that casein protein is taken immediately before bed (or within a 30-minute window if you want to be specific) increased whole-body protein synthesis rates and improved the subjects’ net protein balance. An increase of 22%.

One of the reasons for casein being so effective pre-bed is that it is slow releasing because casein has slower motility than whey protein, it can spend more time releasing amino acids (particularly Leucine) into the blood. This means that it can elevate protein synthesis for longer than whey protein (16).

6. Casein protein may help improve sleep quality. A lot of articles and fitness professionals claim that casein is good for improving sleep quality, but there is surprisingly little evidence for this. One of the main reasons why casein is said to improve sleep is that it contains tryptophan. This is an amino acid that helps regulate sleep, but only 1.1% of casein is made up of tryptophan (17).

There are other foods (such as egg whites) that contain much higher quantities of tryptophan than casein.

In fact, it might not have anything to do with tryptophan, casein may help improve sleep quality because it contains a peptide called AlphaS-1 Peptide. This peptide is known for reducing anxiety (called an anxiolytic) and reduce stress.

A study on rats suffering from chronic stress found that AlphaS-1 peptide found in casein protein helped to improve sleep (18).

You could also theoretically claim that casein protein may help reduce stress and anxiety too, but there are no human studies that confirm this.

7. Casein protein can help build muscle. The link between protein supplementation and muscle mass is well known. Provided you are performing adequate exercise whey or casein protein will absolutely help increase muscle mass.

A systematic review on the effects of protein supplements on muscle mass found that protein supplementation can enhance gains in muscle mass (hypertrophy) and strength, it also found improvements in aerobic and anaerobic performance (19).

Provided there is enough stress on the muscles from resistance exercise of course.

A 2012 study looked at the effect of protein supplementation on the muscle mass of both young people and older people (20).

It found that prolonged exercise, combined with whey, casein, or a combination of whey and casein led to significant increases in both populations.

A similar study found that whey and casein protein were more effective than soy protein when it came to muscle accretion in both young and elderly people (21).

There was an interesting study that looked to find the best protein supplement, comparing whey, casein, bovine colostrum (also a milk protein), and soy protein. They found that:

“In athletes supplementing their diets with additional protein, casein has been shown to provide the greatest benefit for increases in protein synthesis for a prolonged duration. However, whey protein has a greater initial benefit for protein synthesis. These differences are related to their rates of absorption. It is likely a combination of the two could be beneficial” (22).

8. Casein protein can help build greater strength when combined with resistance exercise. If casein protein can increase muscle mass, then it stands to reason that it can also help build strength too. A 2013 study found that a combination of resistance exercises and pre and post-workout protein shakes led to changes in performance, they found no difference between casein and whey protein (23).

A 2006 scientific review article found that combining whey and casein protein led to the greatest gains in strength and fat-free mass over a 10 week period (24).

A similar study in 2005 found that milk protein (a combination of whey and casein) combined with a 12-week training program led to greater gains in strength and hypertrophy than a soy-based protein (25).

9. Casein protein can help with weight loss. A study out of the Netherlands showed that casein protein could help increase the metabolic rate during sleep. The study also showed a massive 33% increase in feeling full, helping you eat less food overall (26).

Another 2004 study showed that casein could help men double their fat loss over a 12 week period (8% vs 4%) (47).

10. Casein protein is long-lasting. Casein is considered a slow-digesting protein because it takes hours for the amino acids to leave the bloodstream. This means muscle tissues have a longer opportunity to use the amino acids for repair work and growth. This is especially beneficial overnight when you are not consuming any protein or amino acids.

11. Casein protein helps promote colon health. In a study performed out of Australia, researchers investigated the health benefits of various proteins and found that dairy proteins promote colon health better than meat and soy (27).

12. Casein protein is good for your teeth. According to a study conducted in the United Kingdom, one way to help prevent a more expensive dental visit might be to consume casein. Their research found that casein proteins have the potential to reduce or prevent the effects of enamel erosion (28).

Side Effects

1. Casein protein can cause minor side effects in people with a dairy allergy. Due to casein being free of lactose, a lot more people are able to consume it than they are other dairy protein sources. But you can still be allergic to it if you have a dairy allergy. The side effects of this can be nausea, bloating, headaches, and similar minor complaints, but nothing too serious.

2. Casein protein has been found with low levels of contamination. One issue that has surfaced recently is contamination, a recent study by the clean label project found that many protein powders had levels of lead, cadmium, and BPA within them (29).

Now there should be some context given here, while the levels were higher than expected, they were still well within safe levels. Secondly, milk and egg-based proteins (including casein) were found to be much safer than vegan and plant-based protein powders.

3. Casein protein may lead to a higher risk of mortality in a higher protein diet. There is a lot of debate at the moment on whether high protein diets are safe or not. The worry about kidney problems occurring has finally been laid to rest (protein will not affect healthy kidneys at all) but some studies indicate that lower protein diets lead to a lower risk of mortality in under 65s (30).

That same study also found that people who were over 65 actually benefited from higher protein, possibly due to the increased requirement of Leucine in the elderly (31).

Recommended Dosage

How much protein you require is influenced by many factors, whether you are young or old, whether you are active or inactive (studies have shown that athletes require twice as much protein as sedentary people (32).

If you are looking to build muscle, or lose weight can also affect this. Your body weight and muscle mass can also have an impact, as can your gender.

Examine probably gives the best advice – due to it only considering studies performed on humans, and aiming their information at a variety of individuals.

They break up society into three groups: Athletes and highly active people (1.5-2.2g/kg), people attempting to lose weight while preserving muscle mass (1.0-1.5g/kg), and sedentary people who are not looking to change their body composition (0.8g/kg and up) (30).


When should you take casein protein? Because casein is a slow-digesting protein, its best suited to take it before bed or as a meal replacement instead of post-workout.

Can you be allergic to casein protein? If a glass of milk or a slice of pizza causes swollen lips, hives, or other significant symptoms, you may have an allergy to casein, a protein in milk. Another milk protein associated with food allergies is whey. Some people are allergic to both casein and whey

Are protein powders regulated by the FDA? Protein powder is viewed as a dietary supplement by the FDA. As a dietary supplement, the FDA allows manufacturers to evaluate the safety and labeling of their products independently. Though this is the case, however, consumers can still a large amount of research independently for the best possible information about the protein powder they choose

Is whey or casein protein better? Whey is considered a “fast” protein because it is rapidly digested in as little as an hour, whereas casein is a “slow” protein that is digested over several hours. Neither is better than the other as they serve different purposes.

Are protein shakes safe for long-term consumption? Unfortunately, there is not much information or research to confirm the long-term effects of protein powder use. It is important that consumers understand some of the risks involved with unknown factors. Despite this, however, protein powder has so far not been linked to any chronic issues or concerns.

Do eggs contain casein protein? Eggs do not contain casein, though some dishes that contain eggs may have it, depending on ingredients.

Is casein protein cancerous? most milk proteins including casein can promote the growth of both normal cells and cancer cells. However, this isn’t confirmed in human studies to be harmful.

Can I lose weight by just drinking protein shakes? Manufacturers of protein shakes may claim that their products help decrease body fat or promote weight loss, but protein shakes aren’t a magic bullet for weight loss. Replacing meals with protein shakes may help you reduce your daily calories, which can help you lose weight.

What foods have casein protein in them? Because casein is a protein, it’s found mostly in dairy products with moderate-to-high protein content such as low-fat milk, yogurt, kefir, and cheese.

Is it ok to take casein protein in the morning? Yes, anytime that isn’t post-workout is ideal for casein.

Is ghee free of casein protein? Ghee or clarified butter (also known as drawn butter) is a casein-free alternative to regular butter. Both ghee and clarified butter have the milk proteins casein and whey removed and what remains is butter fat.

What is soy lecithin and why is it in many casein protein powders? Soy lecithin is used in protein powder (and many other foods) to help stabilize certain mixtures of ingredients. While it’s generally a good idea to limit your intake of soy products (and soy protein in particular), there’s a big difference between what’s in casein supplements and eating tofu every day. Unless you are very allergic to soy, you can rest assured that the tiny amount of soy lecithin in casein protein powders is harmless.

How much casein protein can I eat per day? There really is no upper limit too much you can consume per day. Anecdotal evidence, however, suggests that getting at least 50% of your daily protein from whole food sources is a good rule of thumb.

Do protein shakes cause weight gain? Weight gain occurs when you eat more calories than you burn. If your daily protein shake contains 200 calories in excess of your body needs, it could result in a gain of 21 pounds in a year.

Is slow-digesting casein protein better for building muscle? There is evidence that using a slower-digesting protein like casein may result in more muscle growth over the long term. More research is needed to confirm these findings, however.

Is casein protein powder good for weight loss? Yes, casein is a “slow” protein and is believed to help improve the chance of muscle growth and fat loss.

Do protein shakes make you fart? Sometimes protein can cause intestinal distress leading to protein farts. Taking a probiotic or a high-quality protein powder should remedy this. You may need to switch to a different type of protein if it persists.

What type of protein shake is best for me? Protein shakes come in a variety of types. The best way to determine which protein shake is right for you; it is always a good idea to identify your specific goals and research which type will give the best results.

Can you ever have too much protein? Generally, the recommended amount of protein would want to be maintained. Though the likelihood of ingesting too much protein per day is not likely, it is important to maintain a balanced diet whenever possible.

Does casein protein have any side effects? Casein may cause some digestive distress, especially in those who are lactose intolerant.

Does casein protein spike insulin? Casein protein does not cause the same massive spike in insulin that whey protein does.

Is casein protein bad for you? Casein can cause minor side effects in people with a dairy allergy. Due to casein being free of lactose, a lot more people are able to consume it than they are other dairy protein sources. But you can still be allergic to it if you have a dairy allergy.

Do whey and casein combined lead to better results? There seems to be a growing consensus that combining whey and casein together leads to better results. You could either take a scoop of each, or have a whey protein shake post-workout, and a casein protein shakes before bed. Lots of supplement companies pre-mix the two together but find the option that provides the best value for money and protein per serving.


Casein protein is a great protein supplement for people looking to build muscle, increase strength, preserve muscle, or lose weight. It appears to have a few benefits over whey protein when it comes to satiety and protein synthesis, but whey has other benefits that casein doesn’t.

There are essentially no side effects to taking casein unless you have a lactose or dairy allergy. The fear of contamination is overblown, particularly for animal sources of protein. But you can always check the clean label project website to find which products have the lowest levels.

If you are an athlete, bodybuilder, or just someone who goes to the gym twice per week, there are many benefits to taking casein. Even sedentary people will benefit from casein, with increased satiety, improved metabolism, and better sleep (possibly).

For Healthtrends #1 recommended Casein supplement, click here.

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