What Is Casein?: Uses, Benefits, and Side Effects of Casein Protein Powder

David Fang
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person holding protein shake while sitting next to dumbbells

Let's take a moment to discuss protein powder. Specifically, what is casein protein and how can it benefit me? One of the most important aspects of optimal health is ensuring you are getting the right balance of macronutrients. With diet, having adequate amounts of proteins, fats, and carbohydrates are essential to energy, longevity, and health.(1) Protein is essential for a host of various functions.

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Benefits and Role of Protein in the Body

Proteins, which are clusters of amino acids, play a major role in nearly all chemical reactions in the body. They help with proper gene expression, regulate the immune system, and help build and maintain muscle with exercise.(2) Some of the best amino acids, such as tryptophan, tyrosine, and arginine, found in protein, play a vital role in cognitive performance, stress management, and healthy brain function.(3)

Proper Dosing: How much protein should I be taking?

According to the American College of Sports Medicine, protein should comprise 10-30 percent of your daily caloric intake, depending on your needs.(4) The American Dietetic Association recommends intake of 0.8 grams of protein per pound of body weight for the average person.(5)

Despite its importance, many people need help to consume enough protein. Even with healthy food and lifestyle choices, achieving an ideal protein intake may take time. Factors like age, underlying conditions, genetic disorders, and even some medications can affect how your body synthesizes protein, requiring even more intake to meet requirements.(6)

Many people are turning to casein protein powder to help bridge the gap. Let's look at the benefits, side effects, and something you should consider when incorporating casein protein into your nutritional plan.

What Is Casein?

Casein is a protein found in dairy products such as milk, cheese, yogurt, and dairy-based infant formula. It is the most abundant protein within these foods, making up 80% of their protein content. Casein gives milk its white color. Active ingredients include calcium, peptides, and amino acids.

Our Top 3 Casein Protein Picks

Uses for Casein

They often sell this protein as a powder, and it serves as a dietary supplement. Bodybuilders, athletes, and active people often use it to improve performance, complement recovery, and increase muscle size.

Casein has four subtypes. However, as a dietary supplement, there are two forms of casein on the market:

  • Micellar casein: The most common and is characterized by a slower rate of digestion
  • Casein hydrolysate: Predigested and absorbed more quickly

For those who are already making healthy lifestyle choices but still aren't able to hit their protein targets, casein can help make up the difference. This is especially helpful for people who do not partake in meat-based protein sources, such as vegetarians.

Individuals with conditions that require additional protein supplementation to meet daily requirements because of poor protein synthesis can use casein.

Benefits of Casein

Essential amino acids are important for the body to operate properly. Since your body doesn't produce them, we must derive them from food sources and supplementation. Casein is referred to as a complete protein, meaning it contains all the essential amino acids that your body needs. (7)

There is research that shows it can serve as an anti-catabolic to prevent breakdown and preserve muscle mass.(8) It's for this reason that a growing number of bodybuilders will use this during their muscle-building phase to promote growth and in their cutting phase in order to preserve as much muscle mass as possible while in a caloric deficit.

Casein can be beneficial for other types of athletes, as well. In endurance sports, studies confirm that the addition of protein during endurance exercise can suppress muscle breakdown afterward. It can also help reduce the amount of soreness you feel during recovery.(16) This can cause improved recovery times that allow you to get back to training sooner while maintaining muscle mass essential for performance.

Casein contains several bioactive compounds—chemicals found in small amounts within certain foods that promote good health. There is promising research underway to determine their effectiveness at reducing things like cancer and heart disease.(9)

Micellar casein's slow absorption rate can help on several fronts. Its "time-release" qualities can translate to a slower, more measured release of amino acids to your cells over longer periods of time. It can also play a role in helping your body make use of the protein it consumes resulting in a reduced risk of muscle breakdown for fuel.(10)

Contrary to what some supplement manufacturers will try to tell you, casein protein is not a magic formula for muscle growth. With that said, if you are protein deficient, casein protein is a great tool that may help bring you into a high enough protein surplus to elicit muscle growth.(11) This is less a direct benefit of casein and more to do with the fact that your body needs protein to grow in general.

There is emerging preliminary research that shows casein protein may help provide additional benefits such as:

  • Reduction in blood pressure: Some research suggests a correlation between bioactive peptides found in casein and a host of immune and blood pressure benefits.(9)
  • Lower triglyceride levels: A study showed that ingredients in casein could reduce triglyceride levels by up to 22% after consuming a meal.(12)
  • Antioxidant benefits: Peptides in casein may help fight the accumulation of harmful free radicals.(13)
  • Improved body composition and fat loss: Several studies show significant improvements in subjects who took in a protein supplement when it came to their fat loss and muscle gain.(14) In one instance, fat loss was three times greater in the test group than in the placebo group over a 12-week period.(15)

We've chosen to only include potential benefits that are accompanied by science-backed data. It's important to note that nutritional supplements and their claims are not evaluated by the FDA. As with any other dietary supplement, base your decision regarding casein protein on scientific data.

Please take additional claims by supplement companies with a heavy dose of skepticism and also require that they back up their listed benefits with science and, ideally, third-party studies from respected, impartial institutions.

With that said, it's clear that casein protein can provide a host of benefits that can impact many aspects of your health.

Side Effects of Casein

For most healthy people, casein supplements are generally safe to take. Most adults do not experience negative side effects as a direct result of casein protein. However, as with any dietary supplement, it is important to take casein as recommended and for its intended purposes. Complications or side effects can occur if you take an excessive amount well above your daily needs. This is a pitfall that some people trying to build muscle will encounter.

To reduce issues with overconsumption, we recommend you examine the protein dosage guidance from both the American College of Sports Medicine and The American Dietetic Association.(4, 5) Another aspect to consider is to only source casein protein from high-quality sources and brands that are committed to best practices.

Casein Precautions

As with anything related to your health, casein may not be suitable for all people. It is always best to consult with a medical professional or registered dietitian about your specific situation before beginning.

While the risk of side effects is very low, there are some additional things to consider when incorporating casein protein into your lifestyle:


Milk-related allergies often develop during infancy and into early childhood and adulthood. However, a milk allergy may not exclude you from being able to take casein. Hydrolyzed casein protein has been further processed and can help some individuals with milk allergies receive the nutrients and benefits without discomfort.

It's important to note that a milk allergy differs from lactose intolerance—an intolerance to milk's natural sugar. People with this kind of intolerance may still take some forms of casein protein with little difficulty.

Casein Dosage

Your ideal amount of casein intake will vary depending on things like age, underlying conditions, physical activity, height, and weight. While there are benefits to taking casein protein, it's not meant to be a total replacement for the protein that you get from a healthy diet and whole protein sources.

It is worth taking time to research the ideal timing of taking in casein protein. For example, taking protein before or after a workout may provide more growth benefits than at other times.(18)

If you have questions regarding how much you should take, consider consulting with a medical professional.

Sources of Casein

Casein is readily available in different forms from various sources. While casein protein supplements are convenient, most health professionals recommend getting your protein from a variety of sources for the host of additional benefits they bring.

Casein sources include:

  • Food: Things like milk, yogurt, and cottage cheese. They provide additional nutrients that are important for proper protein synthesis and unlock additional benefits affecting health and wellness.
  • Casein supplements: Most commonly protein powders of different flavors and forms of casein.

FAQs About Casein Protein

What does casein do to the body?

Casein is a form of protein, a vital macronutrient. It aids in a host of processes within the body, such as healthy body composition, improved metabolism, efficient recovery, and muscle building and retention.

What foods have high casein?

Casein can be derived from dairy products such as milk, yogurt, and cheese. For example, a cup of 2% cottage cheese can contain up to 24 grams of protein, most of which is casein.

What is the difference between dairy and casein?

Dairy is any food made from the milk products of different animals, such as cows. Casein is a type of protein found in milk.

What are the symptoms of casein intolerance?

With lactose intolerance, symptoms can include upset stomach, bloating, cramping, and nausea. (19) To help ease symptoms, consider opting for a hydrolyzed version of casein protein.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.


  1. Venn B. J. (2020). Macronutrients and Human Health for the 21st Century. Nutrients, 12(8), 2363. https://doi.org/10.3390/nu12082363
  2. Poos, M. I., Costello, R., & Carlson-Newberry, S. J. (1999). Conclusions and Recommendations from the Workshop Report The Role of Protein and Amino Acids in Sustaining and Enhancing Performance Submitted June 1999. In Committee on Military Nutrition Research: Activity Report: December 1, 1994, through May 31, 1999. National Academies Press (US).
  3. Lieberman, H. R. (1999). Amino acid and protein requirements: cognitive performance, stress and brain function. The role of protein and amino acids in sustaining and enhancing performance, 289-307.
  4. American College of Sports Medicine. (2015). Protein intake for optimal muscle maintenance. Anton, S.
  5. Rodriguez, N. R., DiMarco, N. M., & Langley, S. (2009). Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance. Journal of the American Dietetic Association, 109(3), 509-527.
  6. Scheper, G. C., van der Knaap, M. S., & Proud, C. G. (2007). Translation matters: protein synthesis defects in inherited disease. Nature reviews. Genetics, 8(9), 711–723. https://doi.org/10.1038/nrg2142
  7. Haug, A., Høstmark, A. T., & Harstad, O. M. (2007). Bovine milk in human nutrition--a review. Lipids in health and disease, 6, 25. https://doi.org/10.1186/1476-511X-6-25
  8. Marchesini, G., Zoli, M., Dondi, C., Bianchi, G., Cirulli, M., & Pisi, E. (1982). Anticatabolic effect of branched-chain amino acid-enriched solutions in patients with liver cirrhosis. Hepatology (Baltimore, Md.), 2(4), 420–425. https://doi.org/10.1002/hep.1840020405
  9. Mohanty, D. P., Mohapatra, S., Misra, S., & Sahu, P. S. (2016). Milk derived bioactive peptides and their impact on human health - A review. Saudi journal of biological sciences, 23(5), 577–583. https://doi.org/10.1016/j.sjbs.2015.06.005
  10. Dangin, M., Boirie, Y., Garcia-Rodenas, C., Gachon, P., Fauquant, J., Callier, P., Ballèvre, O., & Beaufrère, B. (2001). The digestion rate of protein is an independent regulating factor of postprandial protein retention. American journal of physiology. Endocrinology and metabolism, 280(2), E340–E348. https://doi.org/10.1152/ajpendo.2001.280.2.E340
  11. Campbell, B., Kreider, R. B., Ziegenfuss, T., La Bounty, P., Roberts, M., Burke, D., Landis, J., Lopez, H., & Antonio, J. (2007). International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 4, 8. https://doi.org/10.1186/1550-2783-4-8
  12. Mariotti, F., Valette, M., Lopez, C., Fouillet, H., Famelart, M. H., Mathé, V., Airinei, G., Benamouzig, R., Gaudichon, C., Tomé, D., Tsikas, D., & Huneau, J. F. (2015). Casein Compared with Whey Proteins Affects the Organization of Dietary Fat during Digestion and Attenuates the Postprandial Triglyceride Response to a Mixed High-Fat Meal in Healthy, Overweight Men. The Journal of nutrition, 145(12), 2657–2664. https://doi.org/10.3945/jn.115.216812
  13. Rival, S. G., Boeriu, C. G., & Wichers, H. J. (2001). Caseins and casein hydrolysates. 2. Antioxidative properties and relevance to lipoxygenase inhibition. Journal of agricultural and food chemistry, 49(1), 295–302. https://doi.org/10.1021/jf0003911
  14. Verreijen, A. M., Verlaan, S., Engberink, M. F., Swinkels, S., de Vogel-van den Bosch, J., & Weijs, P. J. (2015). A high whey protein-, leucine-, and vitamin D-enriched supplement preserves muscle mass during intentional weight loss in obese older adults: a double-blind randomized controlled trial. The American journal of clinical nutrition, 101(2), 279–286. https://doi.org/10.3945/ajcn.114.090290
  15. Demling, R. H., & DeSanti, L. (2000). Effect of a hypocaloric diet, increased protein intake and resistance training on lean mass gains and fat mass loss in overweight police officers. Annals of nutrition & metabolism, 44(1), 21–29. https://doi.org/10.1159/000012817
  16. Jäger, R., Kerksick, C. M., Campbell, B. I., Cribb, P. J., Wells, S. D., Skwiat, T. M., Purpura, M., Ziegenfuss, T. N., Ferrando, A. A., Arent, S. M., Smith-Ryan, A. E., Stout, J. R., Arciero, P. J., Ormsbee, M. J., Taylor, L. W., Wilborn, C. D., Kalman, D. S., Kreider, R. B., Willoughby, D. S., Hoffman, J. R., … Antonio, J. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14, 20. https://doi.org/10.1186/s12970-017-0177-8
  17. Dupont, C., Bradatan, E., Soulaines, P., Nocerino, R., & Berni-Canani, R. (2016). Tolerance and growth in children with cow's milk allergy fed a thickened extensively hydrolyzed casein-based formula. BMC Pediatrics, 16(1), 1-8.
  18. Schoenfeld, B. J., Aragon, A., Wilborn, C., Urbina, S. L., Hayward, S. E., & Krieger, J. (2017). Pre- versus post-exercise protein intake has similar effects on muscular adaptations. PeerJ, 5, e2825. https://doi.org/10.7717/peerj.2825
  19. Swagerty Jr, D. L., Walling, A., & Klein, R. M. (2002). Lactose intolerance. American family physician, 65(9), 1845.