The Differences Between Whey, Pea, and Casein Protein

When it comes to nutritional supplements, protein powders offer one of the biggest bangs for your buck. Plenty of research validates the positive role they can play in helping you hit your diet and fitness goals more quickly. But those giant tubs aren’t cheap. After all, they’re a month-worth of nutrition. So before you make the investment, you ought to first understand some basic protein principles. As the Romans said, Praemonitus, praemunitus (meaning forewarned is forearmed). Once you know what’s good when and why, you can then focus on more pleasurable dilemmas—like which products taste best.

Most people know that protein has something to do with muscle. And it’s true that you need dietary protein to promote growth. But there’s more to it. Like carbohydrates and fat, protein is a crucial nutrient your body needs every day. Protein is key to repairing damaged cells and tissue throughout your body, is needed to synthesize hormones, and is a supporting player in scores of other metabolic activities not immediately tied to building your biceps. Among other things, you need protein to keep your bones strong (calcium alone doesn’t do it), which should be reason enough for athletes in training to sit up and take note.

Less appreciated is protein’s role in satiety. For most of us, getting to the body and fitness level we want is a two-sided coin of exercise and diet. If you’re trying to get lean, consuming too many calories will offset the cardio and resistance hours you’re putting in, making workouts frustrating. Since protein helps you stay full, it makes it easier for you to stay within your ideal calorie range.

But even those not on a robust fitness plan may benefit from protein’s satiety profile. Analysts say the next big target for protein marketers will be the general, weight-conscious public. Always looking for a silver bullet, consumers may embrace protein supplements to help them lose or keep off unwanted pounds.

Just as carbohydrates come in different forms (starches, high glycemic carbs, low glycemic carbs, and simple sugars), different protein sources have different effects on performance. By eating the right kind of protein at the right point in your routine, you can max out each source’s benefits. To avoid writing a book, we’ll focus below on three of the most common protein sources found in stores today: Whey, pea, and casein. But the principles are the same for others, like soy, dairy, beef, hemp, and rice.

How the Body Assimilates Dietary Protein
Whether it originates in a cow or a tilled field, the human body digests dietary protein in two places: the stomach and the small intestine. In each case, special acids and other chemicals break the protein down into peptides, enzymes, and amino acids, which in turn do useful things like build muscles, repair DNA, and help make neurotransmitters.

In the stomach, hydrochloric acid combines with pepsinogen to make pepsin, the body’s chief digestive enzyme and the one compound we have that can digest collagen, a main component of animal connective tissue. Once created, pepsin begins to dissolve protein’s chemical bonds and this releases amino acids.

When the protein you’ve eaten moves from the stomach to the small intestine, the pancreas releases two more enzymes: Trypsin and chymotrypsin. These dissolve the protein further into its component amino acids, which it’s worth noting are extremely tiny organic compounds. They’re so small, in fact, that they penetrate the intestinal lining and work their way into the bloodstream by way of small blood capillaries.

It’s the combination of which amino acids the digestive process releases and how quickly the amino acids get into the blood (how bioavailable they are) that sets one protein source apart from another. Exploiting these differences can help you maximize your effort in the gym, repair, and grow your muscles after a sweat session, and avoid hunger attacks that can send you scrounging for diet-busting junk food.

When You Should Consume Whey
Whey is among the most widely consumed protein supplements. It comes from the translucent, liquid part of milk that’s left over from cheese making and is a complete protein, meaning it contains all nine of the amino acids humans need.

Whey is called a fast-digesting protein because once you consume it your stomach pushes it on quickly. That leads to a big, swift bump in the amino acids circulating in your blood, making it a good choice for a post-workout snack. About 1-2 hours after you exercise, your body experiences a spike in protein synthesis, during which it works harder to repair the muscles you just broke down. If you consume whey within 30 minutes of your workout, your body can absorb the amino acids in time to take advantage of this window and supply your body with the raw materials it needs. In a sense, you’re getting a head start on the muscle building that normally takes much longer to accomplish.

But unless you plan to keep sipping whey throughout the day and evening, its quick-hit nature makes it less than ideal for the slow-and-steady muscle growth that we typically think of happening in the 12 to 24 hours after an intense workout. That’s where it’s cousin, casein protein comes in. But note because both whey and casein come from cow milk, neither is well suited for people with dairy allergies.

The Best Time to Have Casein Protein
Casein is the main protein component in cow’s milk, and happens to be what makes milk white. It, too, is a complete protein. Unlike whey, which is quickly pushed through the stomach into the small intestine, casein protein forms a gel once it reaches the stomach.

It’s that gel—along with chemical qualities that make it relatively insoluble—that make casein a slow-digesting protein. Unlike whey, casein keeps on giving, steadily releasing amino acids over several hours. That makes casein protein another good post-workout supplement.

Recently, researchers have found a synergistic effect is created when whey and casein protein are combined. Taking whey within 30 minutes of your working and then taking casein is right before bed is the ideal combination. That’s because casein helps create an “anti-catabolic” environment in your body. During sleep, there’s a six-hour window when you body synthesizes protein. The “slow drip” nature of casein provides a steady supply of amino acids to make the most of that window.

What About Pea Protein?
Pea protein has been showing up on store shelves for the last several years. And it’s easy to see why. It’s 100% plant-based, so vegans and people with dairy allergies can use it. Pea protein is digested at a medium rate, providing satiety levels that are about the same as whey and casein protein. Like most plant-based proteins, it’s hypoallergenic so you probably won’t develop an allergy even after prolonged use. Finally, perhaps because it’s seen as a “natural alternative” to whey and casein, manufacturers tend to leave out a lot of the additives and artificial ingredients you often find in milk-based products.

One downside is that pea is not a complete protein and shouldn’t be used as your main source of dietary protein. But as a supplement, it’s got a lot going for it. And, when you combine the three proteins—whey, pea, and casein—in a recovery drink for example, you create a prolonged delivery system that maximizes absorption. And who doesn’t like a little extra absorbing?

Even with all the existing protein supplements on the market, research continues into new sources and combinations. You can even buy beef-based protein powder, and coming down the pike from more than one company are supplements derived from lab-grown crickets.

So explore what’s out there. Unlike a lot of over-hyped supplements, protein really does help. And since you’re going to be eating it anyway to stay alive, you might as well make smart protein choices that help meet your fitness goals.