Casein protein

About Casein protein

The dominant protein of milk, making up about 80% of milk protein. Micellar casein retains its native micelle structure and clots in the stomach; caseinates are chemically processed and do not.

Casein is defined by its digestion kinetics. In the stomach it forms a clot that empties slowly, producing a low, prolonged rise in blood amino acids rather than whey’s sharp peak — the original tracer study described whey as "fast" and casein as "slow" protein, and the terms stuck. That property gives casein one genuinely tested application: taken before sleep, 30–40 g raises overnight muscle protein synthesis and improves training adaptations across several trials. It is one of the few timing claims in supplementation that has actually been examined rather than asserted.

Sold as

Micellar casein powder, Calcium caseinate, Milk protein blend, Cottage cheese as a whole food

Standardised to

Protein percentage and whether micellar or caseinate — the two behave differently in the stomach — a product without this marker may not resemble what was studied.

Also known as

Micellar casein, Calcium caseinate, Slow protein

Regulation: Sold as a food or dietary supplement with no pre-market efficacy review. The same contaminant testing considerations apply as for other protein powders.

What the research used

The amounts, forms and durations published trials of Casein protein actually administered.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

In the food catalogue

The whole-food form, where one exists. The evidence for a concentrated extract rarely transfers to the food, or the other way round — these are cross-links, not equivalents.