There’s a new alternative to whey, casein and soy — but can it match up?

In the old folktale “Stone Soup,” a wanderer teaches a miserly woman all about sharing by successfully making a delicious soup out of a stone … and plenty of regular old soup ingredients that he sneakily convinces his host to spare. “Soup from a stone,” she says upon tasting the final outcome. “Fancy that!”
     Confused as to why we’re reliving our childhood? True, folktales and fitness don’t generally share pages in this magazine, but we bring this up because we had a variation on the miserly woman’s exclamation running through our heads the whole time we were working on this article: “Protein from a pea. Fancy that!”

Surprise Bounty
Don’t get us wrong; it’s not that peas don’t normally contain protein. In fact, as far as vegetables go, they’re a fairly good source. A half-cup of cooked green peas contains 4 g of protein, and a half-cup of its close relative, the split pea, contains 8 g of protein. But the problem is that, like most proteins from vegetable sources, the protein found in peas is not complete.
     “In order to be considered complete,” says Tabatha Elliott, PhD, who studied protein at the University of Texas Medical Branch (Galveston), “it has to contain all nine essential amino acids, the ones that can’t be synthesized in the body and therefore have to be consumed.” Not many food sources contain all nine; the only ones are meat products (including dairy and eggs), soybeans and quinoa.
     To be clear, most vegetables contain most aminos, just not in “quantities sufficient to make them complete proteins,” says Elliott. Combining different foods in one meal, however, is one way to ensure you’re getting adequate amounts of all aminos. For example, grains tend to be low in lysine, while legumes are low in methionine and cysteine. Eat a bowl of rice and beans, though, and you’ll get decent levels of all of the amino acids. But the beauty of a product like pea protein powder is that it comes complete with a full slate of aminos, because to create it, supplement companies concentrate the protein naturally found in peas. (They also remove the majority of the carbohydrates.)

Bodybuilding Boost
This is excellent news for vegans (who won’t touch whey or casein proteins since they’re derived from milk) and those with severe food allergies (who often can’t tolerate soy or milk products). But it’s also good news for the carnivorous allergy-free fitness freak. You could eat nothing but chicken breasts as your protein source, and you would likely achieve your fitness goals. But it’s a much better idea to throw a little fish and some steak into the mix, even some tofu now and again. The same is true of protein powders. Sure, you can stick with your old trusty whey shake, but you’ll be better off if you switch it out for a soy or casein shake — or even go half and half on occasion. Why? Because, as we’ve seen, different foods have different amino-acid profiles. While all complete proteins will contain decent levels of all nine essential aminos, some will contain more phenylalanine, say, while others will have higher levels of valine. “Eating a variety of foods and shakes throughout the day ensures you’re getting good levels of all aminos,” says Elliott, and that can have benefits to muscle growth and beyond.
     For example, most aminos do more than just create protein and muscle, and pea protein powder is particularly high in three aminos that can have powerful effects on your physique:
     Arginine: Nitric oxide is a molecule that acts on blood vessels, causing them to dilate. Wider blood vessels means more blood can flow through, bringing more nutrients to hungry, growing muscles. And the way to increase your body’s nitric-oxide levels is by increasing your arginine levels, as arginine is integral to nitric-oxide production.
     Branched-chain Amino Acids: BCAAs have a fancy acronym, but it just describes their chemical makeup. What it doesn’t tell you is how these three aminos — isoleucine, leucine and valine — are just about the most important aminos in a bodybuilder’s shake. Together, they make up the majority of muscle tissue and are crucial to its creation and repair. But they also kick-start protein synthesis; increase levels of insulin, an anabolic hormone; decrease levels of cortisol, testosterone’s mortal enemy; and even can improve immune function.
     Glutamine: Besides having enormous influence on the health of the intestinal tract (so enormous, in fact, that your body will happily chew up your muscle to supply your intestines with glutamine if you don’t have enough in your blood stream), studies have shown that glutamine is implicated in endurance, muscle recovery after intense exercise and even fat burning.