Whey causes fast release of protein in blood. Casein causes slow release of protein in blood. This can be used e.g. to use use whey after sport and casein before going to bed.

But what about vegan proteins? Where are soy, pea, wheat and rice protein located? Didn't find any information about that.

I am searching for something like whey > soy > wheat > rice > pea >casein (where left if releaseing quicklier and right is releasing slowlier), this is just an example which could be wrong. Till now i only know whey > casein. So it's about "Vegan protein absorption with respect to each other" in terms of absorption speed.

Does somebody know?

  • @C.Lange This question is specificly about soy, pea, wheat, rice protein (vegan protein). While the topic gives some interesting info in general (thank you) it does not answer the question here. Apr 20, 2021 at 18:44
  • Gotcha. Vegan protein absorption with respect to each other.
    – C. Lange
    Apr 20, 2021 at 20:33
  • From some quick googling it seems to be soy>whey>pea but I haven't found robust enough sources on this subject or something comparing all the sources mentioned above....
    – E.Aigle
    Apr 22, 2021 at 4:16
  • I believe the first paragraph adequately answers this question - "If the amino acid profile of one source is identical to another, its potential value or utility is also identical.". This is regardless of source. There is also a linked article that supports this.
    – JohnP
    Apr 22, 2021 at 14:48
  • @JohnP This question is about the speed of absorption, how fast the amio acids are released in the body (so how fast they are e.g. in blood), not about if and what is absorbed. E.g. "Milk's casein proteins actually go about making themselves more difficult to digest, forming small insoluble little balls, or curds, when they reach the stomach. Digestive enzymes have to work hard to break these curds apart, resulting in longer digestive times and slower release of the protein's nutrition." source Apr 22, 2021 at 15:22

1 Answer 1


The reason why casein is considered to be a slower digesting protein is that it curdles inside the stomach, making it difficult to digest, so its amino acids are released slowly. It's reasonable to assume that this effect is unique to casein, and that all other proteins are "fast digesting".

It's also pretty questionable whether this slow-digesting property of casein is actually beneficial, as not only is casein inferior at stimulating muscle growth compared to whey1, but the body also experiences a refractory period in response to elevated blood amino acids, where muscle protein synthesis stops after a while and does not respond to continued elevated blood amino acids2, suggesting that slow-digesting proteins are in general not useful.

That said, this does not appear to have ever actually been tested, i.e. there is no study I could find which fed participants protein before bed, divided into whey and casein groups, and measured total overnight muscle protein synthesis. So any claims about which is better for consumption prior to bed should be regarded as merely speculative.


  1. Tang, J. E., Moore, D. R., Kujbida, G. W., Tarnopolsky, M. A., & Phillips, S. M. (2009). Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology, 107(3), 987–992. https://doi.org/10.1152/japplphysiol.00076.2009
  2. Mitchell, W. K., Phillips, B. E., Hill, I., Greenhaff, P., Lund, J. N., Williams, J. P., Rankin, D., Wilkinson, D. J., Smith, K., & Atherton, P. J. (2017). Human skeletal muscle is refractory to the anabolic effects of leucine during the postprandial muscle-full period in older men. Clinical Science, 131(21), 2643–2653. https://doi.org/10.1042/cs20171230

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