This is a short piece from clinical nutrition writer Brian Rigby on why pea/rice protein beats whey and soy, at least for people looking to lose weight.
"Pea and rice protein, when mixed together, form a "complete protein" (pea is low in sulfur-containing amino acids while rice is high in them). While whey and soy are also complete proteins, both have a number of associated issues as well, including their allergenic nature. Soy, in particular, can be problematic for people as it can cause sensitivities and inflammation and can also be higher in isoflavones than soy products which have not been processed and concentrated like soy protein isolate has been.
Whey does not contain isoflavones, but it can still be a trigger for sensitivies in certain people. In addition, due to the extremely rapid absorption of whey protein, much of it will end up as nitrogen waste in the urine unless you are a serious athlete and just going to or returning from exercise! Pea/rice protein, on the other hand, is digested and absorbed more slowly, causing it to be more satiating for people trying to lose weight and ensuring that the majority of it goes towards maintaining lean body mass, not getting excreted as waste.
Despite what you may have heard about vegetable proteins, pea/rice protein is highly digestible and readily absorbed. If you are concerned about exercise and protein for recovery, pea/rice protein is comparably high in the branched-chain amino acids (BCAAs), arginine, and lysine as whey protein, making it equal in terms of muscle recovery, strength training, and fat burning."
I dislike the term "complete protein" because it's the rare plant indeed that does not contain at least some of every amino acid--thus, they are all technically 'complete'. Instead, we should be more concerned whether a protein has high amounts of the amino acids we benefit from getting more of. BCAAs top this list.
BCAAs are the most important amino acids for building and maintaining muscle, and they're also the amino acids our body turns to when it needs to boost blood sugar (because they can be easily turned into glucose when needed). Increasing BCAA intake is linked with weight loss, but we're not 100% certain why yet. It may be that because they help dieters maintain muscle, they continue burning more calories. It could also be that they stabilize blood sugar and prevent crashing. Probably it's a combination of both plus some other reasons we still don't know.
What About Potato Protein? Potato protein is high in the BCAAs pea protein lacks. Pea protein does have BCAAs, and when compared to most other vegan proteins it's quite good, but potato just happens to be better, as is rice. So, pea is usually mixed with either pea or potato to fortify it with extra BCAA-power.
You might be wondering why we use pea protein at all. Maybe you've heard that it is high in amino acids others are lacking, so it complements the rice or potato protein. There's a grain of truth there, but it's not actually the real reason (the amino acids it complements aren't all that important, and you probably get more than enough of them elsewhere in your diet). The real reason is that it has a great taste and texture, something that potato and rice lack (potato protein is bitter, rice protein is gritty). You can get pure versions, but they lack important aestethic qualities and usually sit lonely in your cabinet as a result. Protein shakes are MUCH easier to do when they taste and feel nice!
Bottom Line: So yes, pea/potato is a "complete protein" and a suitable alternative to pea/rice!
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