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Supplement Reviews: Casein!

Casein protein is a milk protein extract recognized for its excellent amino acid profile, slow digestion, and interesting peptides...

What Is It?

Casein protein is a milk protein extract recognized for its excellent amino acid profile, slow digestion, and interesting peptides (casomorphins, casokinins, casoxins, etc).

What Does It Do?

Casein protein, like other protein sources, provides a rich amino acid supply to the body. Current data suggest that exercise can increase protein needs and that increased protein intakes can improve the response to exercise training.

Casein protein is slowly digested and this property of casein makes it optimal for consuming during the day as a snack in the form of dairy products or as a protein shake. Since casein slowly enters the blood stream, it has a negligible impact on protein synthesis.

However, casein does have a powerful effect in suppressing protein breakdown. This may promote a better protein status over time.

Where Does It Come From?

Casein protein makes up approximately 80% of the protein in milk. The beneficial properties of casein are partly a result of the amino acid composition and partly a result of the active peptides (the unique amino acid chain configurations that make up casein).

In order to prevent the denaturing (or destruction) of the interesting peptides, appropriate processing techniques are required. Since milk protein isolates contain 80% casein, often people will use the terms milk protein isolate as casein interchangeably.

How Do I Use It?

Casein offers a convenient way to supplement one’s whole food diet with additional protein and amino acids. Usually I suggest using anywhere between 20 and 40g per day of supplemental casein or milk protein.

Protein supplements, however, should never be used as one’s exclusive protein source.

Credibility Rating:

Rating Scale:

4/4 - This supplement/regimen has significant scientific backing and can produce significant benefits in most individuals.

3/4 - There exists a sound theoretical basis for its ergogenic effects; may work in certain individuals; further research is needed to elucidate their respective effects.

2/4 - Science is equivocal, animal data and human data may be conflicting; or mechanism of action may be unclear.

1/4 - Little or no science as well as poor theoretical foundation.

Scientific References:

  1. Coste, M and Tome, D. Milk proteins with physiological activities: II. Opioid and immunostimulating peptides derived from milk protein. Lait, 71, 241-247, 1991.
  2. Dangin, M et al. The digestion rate of protein is an independent regulating factor of postprandial protein retention. Am J Physiol Endocrinol Metab, 280(2), E340-348, 2001.
  3. Demling, R and DeSanti, L. Increased protein intake during the recovery phase after severe burns increases body weight gain and muscle function. J Burn Care Rehabil, 16, 161-168, 1998.
  4. Demling, RH and DeSanti, L. Effect of a hypocaloric diet, increased protein intake and resistance training on lean mass gains and fat mass loss in overweight police officers. Ann Nutr Metab. 44. 21-29, 2000.
  5. Desrosiers, T and Savoie L. Extent of damage to amino acid availability of whey protein heated with sugar. J Dairy Res, 58(4), 431-41, 1991.
  6. Boirie, Y et al. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Natl Acad Sci. 94, 14930-14935, 1997.
  7. Brantl, V, et al. Novel opioid peptides derived from casein. Physiol Chem, 360, 1211-1216, 1979.
  8. Hambraeus, L. Importance of milk proteins in human nutrition: Physiological aspects. In Milk Proteins ’84. Proceedings of the International Congress on Milk Proteins. Galesloot, TE and Tinbergen BJ (eds). Pudoc Wageningen, Luxemburg, 1985.
  9. Mahe, S et al. Gastrojejunal kinetics and the digestion of [15N]beta-lactoglobulin and casein in humans: the influence of the nature and quantity of the protein. Am J Clin Nutr, 63(4), 546-552, 1996.
  10. Ziemlanski, S et al. Balanced intraintestinal nutrition: digestion, absorption and biological value of selected preparations of milk proteins. Acta Physiol Pol, 29(6), 543-556, 1978.
  11. Shah, NP. Effects of milk-derived bioactives: An overview. Br J Nutr. 84 Supplement 1, S3-S10, 2000.

About The Author

John M Berardi is one of the world's foremost experts in the field of human performance and nutrition. His company, Science Link, provides unique and highly effective training, nutrition, and supplementation programs for high level athletes as well as recreational exercisers. John is a prolific author and a sought after speaker and consultant. Visit for more information about John and his team. Also, check out his new DVD entitled No Nonsense Nutrition.

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