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Casein Protein

Out of the 'curds and the whey' of milk, Casein protein is the curds. A dietary protein source with gel-forming capabilities, it is touted to be slowly absorbed in part due to slowing intestinal motility and gel-forming like fiber; adding water makes pudding.

Our evidence-based analysis on casein protein features 26 unique references to scientific papers.

Research analysis led by Kamal Patel .
Reviewed by
Examine.com Team
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Summary of Casein Protein

Primary Information, Benefits, Effects, and Important Facts

Casein protein is one of the two proteins that make up dairy protein (the other being Whey protein). It is typically known as the 'slow' digesting component of milk protein.

Everything you need to know about whey protein

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For less than the cost of a tub of whey, our guide will help you choose the best product for you to help you achieve your health goals.

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Things To Know & Note

Is a Form Of

Other Functions:

Primary Function:

Also Known As


Do Not Confuse With

Milk protein, Whey protein

Casein protein is non-stimulatory, but provides calories which can be used for energy purposes.

How to Take Casein Protein

Recommended dosage, active amounts, other details

Like any protein supplement, casein protein supplements are dosed in relation to dietary protein goals and how much dietary protein is consumed via other sources. Protein goals vary from person to person, but a general guide is:

  • If you are an athlete or highly active person currently attempting to lose body fat while preserving lean muscle mass, a daily intake of 1.5-2.2g/kg bodyweight (0.68-1g/lb bodyweight) would be a good target

  • If you are an athlete or highly active person, or you are attempting to lose body fat while preserving lean mass, then a daily intake of 1.0-1.5g/kg bodyweight (0.45-0.68g/lb bodyweight) would be a good target

  • If you are sedentary and not looking to change body composition, a daily target of 0.8g/kg bodyweight (0.36g/lb bodyweight) and upwards would be a good target

Supplementation of casein protein should be in the dose that is required to meet these ranges after dietary protein has been accounted for. If dietary protein has adequately reached these ranges, then protein supplementation is not required.

Obese individuals (body fat over 20/30% for males and females or a BMI greater than 30 without significant levels of muscle mass) should not follow the above recommendations exactly as the state of obesity would overshoot requirements. In these instances, calculate your targets based upon what your weight would be assuming an overweight BMI.

Frequently Asked Questions about Casein Protein

How can you assess protein quality?
Several scales have been developed to rate proteins according to their respective bioavailabilities and, more recently, amino acid profiles. Those scales can help guide your choice of protein, as long as you understand their premises and limitations.

Everything you need to know about whey protein

If you take whey protein, getting our Definitive Guide to Whey is a no-brainer. Learn how much to take, how often, and when to take. Learn about the differences between different types, what to look out for, the tricks supplement companies use, and more.

For less than the cost of a tub of whey, our guide will help you choose the best product for you to help you achieve your health goals.

I want the best whey for me

Research Breakdown on Casein Protein

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Casein is a protein that is derived from the milk of many species; most human consumption of casein comes from bovine (cow) milk.

Casein is the insoluble portion of the milk, whereas whey is the soluble portion; the amount of casein in standard milk protein is approximately 80%, and human milk is variable depending on time spent lactating.[1][2][3][4]

Casein protein, like all protein, is a source of dietary amino acids. As it is an animal source, it is complete in the sense that it contains all essential amino acids in adequate enough numbers for proper human functioning at the minimum level of protein intake recommended.

Casein protein also contains various bioactive peptides. These peptides are partially digested in the stomach, and prior to being broken down into their constituent amino acids they are able to exert effects in the intestines (prior to absorption). These effects may be wide-reaching, and are discussed in the following bullets.

Standard processing of casein involves a separation of the two dairy proteins (casein and whey).

Whole milk protein is treated with a compound known as a 'coagulant', usually chymosin[5], which serves to coagulate (congeal, or solidify) the casein fragment. This is a step crucial to cheese making (which requires casein to provide a solid foundation) but is also significant for separating the wheys and casein (curds).[6][7]

With the casein fragment more solid, the whey fragment (still liquid) is then separated from the casein through a process called syneresis. The degree of syneresis varies depending on what the end product (usually cheese) would be, and can be manipulated by salt[8], acidity[9], enzyme treatment[10] and physical disturbances[11] amongst other techniques to provide unique flavor and texture to the end product cheese. Casein protein supplementation is more concerned with the extraction of as much whey as possible, which leaves pure casein protein behind.

Micellar casein tends to be produced via microfiltration, which has the ability to concentrate the micellar segments of casein.[12][13]

Casein contains various Bioactive peptides, which can be defined as sequences of amino acids that are contained in dietary proteins and are partially denatured in the stomach to reveal short sequences. These sequences can exert biological effects in the intestines prior to being digested, or may be digested through a peptide transporter.[14]

When supplemented to women at 150mg daily, the AlphaS-1 peptide is known to produce an anxiolytic effect.[15] Two doses of 200mg may be able to reduce the response to perceived stressors.[16] The anxiolytic effect may also provide better sleep in those with high levels of stress.[17]

Similar to the c12 peptide, AlphaS-1 may also have an ability to induce ACE-inhibitor like effects and reduce blood pressure.[18]

AlphaS-1 is also a peptide that is noted to cause allergies, and thus persons allergic to dairy may also be allergic to this peptide in supplemental form.[19]

When administered in the form of tablets, the c12 peptide at a dose of 3.8g daily for 4 weeks is able to reduce blood pressure in pre-hypertensive subjects from an average of 138/87 to 127/80 in one study.[20] This is due to the c12 peptide having the properties of an ACE inhibitor.[21]

Glycomacropeptides can be found in the casein portion of whole milk products, but due to their water soluble nature they leave the casein portion during chymosin treatment at the beginning stages of processing.[22] They do tend to be associated with casein protein as they originate with kappa casein molecules, hence their inclusion in this Examine page. Unless otherwise added afterwards however, they are not a normal component of casein supplementations.

Casoxins and Casomorphins are peptides which are able to act on the opioid system, which is involved in the rate of digestion. The class of casomorphins are opioid agonists (activators) and the casoxins opioid antagonists.[23]

Casein seems to have a higher relative content of casomorphins to casoxins, which may explain the reduced transit speed after consumption (as activation of the opioid system reduces intestinal motility).[24]

It has been shown to have a more relaxing effect at rest and after mental stress when compared to maltitol,[25] which may be related to a specific tryptic hydrolysate found in bovine casein.[26] This AlphaS1 peptide has been shown to reduce stress when ingested by women at 150mg daily.[15]


  1. ^ Kinsella JE. Milk proteins: physicochemical and functional properties. Crit Rev Food Sci Nutr. (1984)
  2. ^ Lönnerdal B, Forsum E. Casein content of human milk. Am J Clin Nutr. (1985)
  3. ^ Kunz C, Lönnerdal B. Re-evaluation of the whey protein/casein ratio of human milk. Acta Paediatr. (1992)
  4. ^ Belloque J, Ramos M. Determination of the casein content in bovine milk by 31P-NMR. J Dairy Res. (2002)
  5. ^ Kumar A, et al. Chymosin and other milk coagulants: sources and biotechnological interventions. Crit Rev Biotechnol. (2010)
  6. ^ Johnson ME, Lucey JA. Major technological advances and trends in cheese. J Dairy Sci. (2006)
  7. ^ Huffman LM, Harper WJ. Maximizing the value of milk through separation technologies. J Dairy Sci. (1999)
  8. ^ Pastorino AJ, Hansen CL, McMahon DJ. Effect of salt on structure-function relationships of cheese. J Dairy Sci. (2003)
  9. ^ Pastorino AJ, Hansen CL, McMahon DJ. Effect of pH on the chemical composition and structure-function relationships of cheddar cheese. J Dairy Sci. (2003)
  10. ^ Lilbaek HM, et al. Improving the yield of Mozzarella cheese by phospholipase treatment of milk. J Dairy Sci. (2006)
  11. ^ Everard CD, et al. Effects of cutting intensity and stirring speed on syneresis and curd losses during cheese manufacture. J Dairy Sci. (2008)
  12. ^ Microfiltration in Cheese and Whey Processing.
  13. ^ Solanki G, Rizvi SS. Physico-chemical properties of skim milk retentates from microfiltration. J Dairy Sci. (2001)
  14. ^ Muro Urista C, et al. Review: Production and functionality of active peptides from milk. Food Sci Technol Int. (2011)
  15. ^ a b Kim JH, et al. Efficacy of alphas1-casein hydrolysate on stress-related symptoms in women. Eur J Clin Nutr. (2007)
  16. ^ Messaoudi M, et al. Effects of a tryptic hydrolysate from bovine milk alphaS1-casein on hemodynamic responses in healthy human volunteers facing successive mental and physical stress situations. Eur J Nutr. (2005)
  17. ^ Guesdon B, et al. A tryptic hydrolysate from bovine milk alphaS1-casein improves sleep in rats subjected to chronic mild stress. Peptides. (2006)
  18. ^ Rousseau-Ralliard D, et al. Inhibitory effect of αS1- and αS2-casein hydrolysates on angiotensin I-converting enzyme in human endothelial cells in vitro, rat aortic tissue ex vivo, and renovascular hypertensive rats in vivo. J Dairy Sci. (2010)
  19. ^ Schulmeister U, et al. Cloning, expression, and mapping of allergenic determinants of alphaS1-casein, a major cow's milk allergen. J Immunol. (2009)
  20. ^ Cadée JA, et al. Bovine casein hydrolysate (c12 Peptide) reduces blood pressure in prehypertensive subjects. Am J Hypertens. (2007)
  21. ^ Townsend RR, et al. A randomized, double-blind, placebo-controlled trial of casein protein hydrolysate (C12 peptide) in human essential hypertension. Am J Hypertens. (2004)
  22. ^ Keogh JB, et al. Effect of glycomacropeptide fractions on cholecystokinin and food intake. Br J Nutr. (2010)
  23. ^ Teschemacher H, Koch G, Brantl V. Milk protein-derived opioid receptor ligands. Biopolymers. (1997)
  24. ^ Taché Y, Garrick T, Raybould H. Central nervous system action of peptides to influence gastrointestinal motor function. Gastroenterology. (1990)
  25. ^ Nakamura H, et al. Influences of casein hydrolysate ingestion on cerebral activity, autonomic nerve activity, and anxiety. J Physiol Anthropol. (2010)
  26. ^ Messaoudi M, et al. Anxiolytic-like effects and safety profile of a tryptic hydrolysate from bovine alpha s1-casein in rats. Fundam Clin Pharmacol. (2009)