Casein Protein

Overview

Casein and whey are the two milk proteins compared in classic digestion research. [4] Casein powders, often sold as "micellar casein", are dietary supplements marketed as slower-digesting protein, often for the evening. In the US the FDA is not authorized to review dietary supplements for safety and effectiveness before they are marketed. [5] For most people a balanced diet already provides enough protein, and protein products are not necessary. [6] Whey is covered on Whey Protein and milk-protein allergy and lactose on Milk Protein in Powders.

Evidence labels used below: evidence in adequately nourished people means trials in healthy people who already eat enough; mixed means studies disagree or are small; position statement is a professional society's summary, not a new trial; physiology study is a short experiment on how the body handles a meal.

What casein does differently

In a classic tracer study in healthy adults, whey caused a dramatic but short rise in blood amino acids, while casein caused a prolonged plateau of moderate rise, probably because of slow stomach emptying. [4] Protein breakdown in the whole body was inhibited by 34 percent after casein but not after whey, and protein synthesis was stimulated by 68 percent after the whey meal against 31 percent after casein. [4] Net leucine balance over seven hours was more positive with casein. [4]

This was one meal in healthy adults. It describes digestion speed. It does not show that casein or whey gives better results over months.

In a small 2009 experiment in young men (six per group) given drinks with equal essential amino acids after leg exercise, muscle protein synthesis was higher after whey hydrolysate than after micellar casein, and the authors linked the difference to how fast the proteins are digested or to leucine content. [7] That too is a short physiology study.

What research shows

The position stand's author list includes affiliations with commercial organizations, so independent trials matter. [9] Proper evidence not found, in the sources we searched, for casein-specific benefits outside exercise or older-adult muscle outcomes; we searched PubMed for casein and whey hydrolysate in resistance training and read the reviews listed above.

Who might consider it

For most people a balanced diet already covers protein. [6] Casein may suit someone who wants a slower-digesting evening protein, but dairy foods can do a similar job. See Protein Powders vs Whole Foods and Protein Timing, Distribution and the Anabolic Window.

Lactose and allergy

Lactose intolerance is different from milk allergy, and tolerance varies between people. [12] The NHS lists protein shakes among processed foods that can contain lactose. [1] The sources we read give no typical lactose amounts for casein powders, so check the label. See Milk Protein in Powders. The NHS lists cows' milk first among common allergic foods, and the FDA names milk among the nine major US allergens. [2][13]

Related

Whey Protein · Plant Protein Powders · Amino Acids & Protein