Casein Protein


Casein is the main protein found in milk. Similar to other animal proteins, casein is a complete protein, providing generous amounts of essential amino acids.1 However, it is digested more slowly than most other animal proteins, resulting in a more prolonged release of amino acids into the bloodstream.2
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This supplement has been used in connection with the following health conditions:

Used forWhy
2 Stars
Athletic Performance
Refer to label instructions
Casein protein is more slowly digested than other animal proteins, resulting in a slower, prolonged rise in blood levels of amino acids, so some speculate that it may better support protein synthesis by the body compared with proteins like whey protein that are more rapidly digested.
Casein protein is more slowly digested than other animal proteins, resulting in a slower yet more prolonged rise in blood levels of amino acids. This has led to speculation that casein may support protein synthesis by the body for a longer period of time compared with proteins, such as whey protein, that are more rapidly digested. However, in two double blind trials, measurements of muscle protein synthesis after leg exercises were similar whether casein or whey protein (either 20 grams or 0.3 grams per 2.2 lbs body weight taken one hour after exercise) was consumed. Other double blind studies have shown that adding protein supplements to a weight-training program improves gains in muscle mass and strength, but only one trial has compared using casein alone to other proteins for improving body composition and muscle strength. In this controlled trial, overweight men were given a low-calorie diet along with a weight training exercise plan for three months. Men who followed this plan and also took 1.5 grams per day of predigested casein protein per 2.2 lbs body weight gained more strength and lean body mass, and lost more body fat than did men using a similar amount of whey protein along with the same diet and exercise plan.
2 Stars
30 grams per day
Casein protein supplements may support weight loss in people on a low-calorie diet.
Casein, the main protein in milk, may prevent weight gain and aid weight loss due to its effect on appetite, calorie burning, and body composition. Numerous studies in animals suggest casein promotes thermogenesis (heat production) and prevents weight gain and body fat growth even in animals with genetic predisposition for, or eating a diet designed to cause, weight gain. In humans, casein protein supplements taken at bedtime have been found to increase resting metabolic rate in healthy active adults, but not in obese men and women. Protein supplements composed of casein, whey, and soy have all demonstrated similar positive effects on weight loss in clinical trials in subjects with overweight and obesity.

How It Works

How to Use It

Some benefits of casein protein have been demonstrated with as little as 20 grams per day. For improving body composition with weight training, 1.5 grams of casein protein per 2.2 pounds body weight per day has been effective.

Where to Find It

Milk protein is 70 to 80% casein, so milk, yogurt, cheese and other dairy products are high in casein. Nondairy foods sometimes contain added casein as a whitening or thickening agent. Casein is also used in some protein supplements.

Possible Deficiencies

People who do not include dairy foods in their diets do not consume casein. However, the amino acids in casein protein are available from other sources, and a deficiency of these amino acids is unlikely in a typical Western diet.


Interactions with Supplements, Foods, & Other Compounds

At the time of writing, there were no well-known supplement or food interactions with this supplement.

Interactions with Medicines

As of the last update, we found no reported interactions between this supplement and medicines. It is possible that unknown interactions exist. If you take medication, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Side Effects

People who are allergic to dairy products could react to casein protein and so should avoid it. Predigested casein protein may cause fewer reactions in people with dairy allergies, but may nonetheless cause reactions in some.3

Some, though not all, preliminary research has suggested that diets high in milk products, and therefore high in casein, might be associated with increased risk of type 1 diabetes and heart disease.4, 5 One type of casein protein has been suggested as the possible contributor to these diseases,6, 7 but other milk proteins have also been implicated in type 1 diabetes,8 and other components of dairy products, such as saturated fat and cholesterol are known to increase heart disease risk.9, 10, 11 At this time, whether casein protein plays a role in the causation of type 1 diabetes or heart disease is unclear and requires more research.

Animal and preliminary human research has also suggested that some types of casein protein might be associated with increased risk or severity of autism.12 Uncontrolled trials have suggested that eliminating sources of casein as well as gluten or other proteins may reduce symptoms of autism to some degree.13 Controlled studies have also reported promising results,14, 15 but have been criticized,16 and a double-blind trial found no effect of a casein- and gluten-free diet on autism symptoms.17 More research is needed to further explore any potential link between casein protein and autism.

Animal research has suggested that a diet high in casein protein (but not a diet with similar amounts of plant proteins) might increase cancer risk.18, 19, 20 No human research has specifically studied casein protein as a potential cancer risk. Preliminary human studies of dairy foods, which are high in casein, find little association between high dairy consumption and cancer risk. For example, milk consumption may be associated with small increases in prostate cancer risk,21 and small decreases in colorectal cancer risk,22 but no change in risk for other cancers.23 More research is needed to determine whether regular use of casein protein supplements affects cancer risk.

As with protein in general, long-term, excessive intake of casein protein may be associated with deteriorating kidney function and possibly osteoporosis. However, neither kidney nor bone problems have been directly associated with casein consumption, and the other dietary sources of protein typically contribute more protein to the diet than does casein.


1. Deutz NE, Bruins MJ, Soeters PB. Infusion of soy and casein protein meals affects interorgan amino acid metabolism and urea kinetics differently in pigs. J Nutr 1998;128:2435-45.

2. Boirie Y, Dangin M, Gachon P, et al. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Natl Acad Sci 1997;94:14930-35.

3. Wal JM. Cow's milk proteins/allergens. Ann Allergy Asthma Immunol 2002;89(6 Suppl 1):3-10.

4. Truswell AS. The A2 milk case: a critical review. Eur J Clin Nutr 2005;59:623-31 [review].

5. German JB, Gibson RA, Krauss RM, et al. A reappraisal of the impact of dairy foods and milk fat on cardiovascular disease risk. Eur J Nutr 2009;48:191-203 [review].

6. Elliott RB, Harris DP, Hill JP, et al. Type I (insulin-dependent) diabetes mellitus and cow milk: casein variant consumption. Diabetologia 1999;42:292-6.

7. McLachlan CNS: b-casein A1, ischaemic heart disease mortality, and other illnesses. Med Hypotheses 2001;56;262-72 [review].

8. Martin JM, Trink B, Daneman D, et al. Milk proteins in the etiology of insulin-dependent diabetes mellitus (IDDM). Ann Med 1991;23:447-52 [review].

9. Tholstrup T. Dairy products and cardiovascular disease. Curr Opin Lipidol 2006;17:1-10.

10. Sun Z, Cade JR. A peptide found in schizophrenia and autism causes behavior changes in rats. Autism 1999:3;85-95.

11. Kamiński S, Cieslińska A, Kostyra E. Polymorphism of bovine beta-casein and its potential effect on human health. J Appl Genet 2007;48:189-98.

12. Sun, Z, Cade JR, Fregly M, Privette RM. β-casomorphin induces Fos-like immunoreactivity in discrete brain regions relevant to schizophrenia and autism. Autism 1999:3:67-83.

13. Christison GW, Ivany K. Elimination diets in autism spectrum disorders: any wheat amidst the chaff? J Dev Behav Pediatr 2006;27:S162-71 [review].

14. Knivsberg, A-M, Reichelt, KL, Høien, T, Nødland, M. Effect of dietary intervention on autistic behavior. Focus on Autism and Other Developmental Disablities 2003;18:247-56.

15. Whiteley P, Haracopos D, Knivsberg AM, et al. The ScanBrit randomised, controlled, single-blind study of a gluten- and casein-free dietary intervention for children with autism spectrum disorders. Nutr Neurosci 2010;13:87-100.

16. Millward C, Ferriter M, Calver S, Connell-Jones G. Gluten- and casein-free diets for autistic spectrum disorder. Cochrane Database Syst Rev 2008;2:CD003498 [review].

17. Elder JH, Shanker M, Shuster J, et al. The gluten-free, casein-free diet in autism: Results of a preliminary double blind clinical trial. J Autism Developmental Disorders 2006;36:413-20.

18. Campbell TC. Dietary protein, growth factors, and cancer. Am J Clin Nutr 2007;85:1667 [letter].

19. Youngman LD, Campbell TC. The sustained development of preneoplastic lesions depends on high protein intake. Nutr Cancer 1992;18:131-42.

20. Youngman LD, Campbell TC. The sustained development of preneoplastic lesions depends on high protein intake. Nutr Cancer 1992;18:131-42.

21. Stacewicz-Sapuntzakis M, Borthakur G, et al. Correlations of dietary patterns with prostate health. Mol Nutr Food Res 2008;52:114-30 [review].

22. Pufulete M. Intake of dairy products and risk of colorectal neoplasia. Nutr Res Rev 2008;21:56-67 [review].

23. World Cancer Research Fund / American Institute for Cancer Research. "The Second Expert Report, Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective." Washington DC: AICR, 2007, p. 129-34 [review].

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