Dr. Rhonda Patrick: Is there a difference with respect to the source of protein supplements? So, for example, if it's sourced from casein versus whey versus egg white protein with respect to— we're talking about skeletal muscle protein synthesis and presumably increases in muscle mass.

Dr. Luc van Loon: Yeah, so this is stuff that we— the whole intrinsically labeled cows, so the cow infusion, getting intrinsically labeled milk, and we extracted whey and casein in order to show the digestion and absorption kinetics and also the capacity to stimulate muscle protein synthesis.

Now, we've done these studies years ago, and that shows that micellar casein is a slowly digestible protein, so the increase in circulating essential amino acids in the blood is more sluggish than when you ingest whey protein, which is a more rapidly digestible protein. And so, the whey protein gets, or is more rapidly digested, greater increases in muscle protein synthesis. And also has a greater anabolic response, greater increase in muscle protein synthesis. Now, we thought that's maybe only because of the more rapid digestion and absorption, so we hydrolyzed the casein, make it more rapidly digestible, so it was just as easily digested and absorbed as the whey, but it still had a lesser response. So that might be due to the lesser amount of leucine in casein than in whey.

Whey has a higher leucine content, and we know that leucine is an amino acid that has very strong signaling properties. So it stimulates the mTOR pathway, and therefore it sets off the whole anabolic cascade. And we also double-checked that by adding free leucine to the casein, and we got a greater response. So in short, we know that the anabolic potential of a protein is related to the rate of digestion and absorption, and at least the amount of leucine in combination with other amino acids. And that's the whole basis of why whey is more popular with athletes than casein. But the differences are very small. And so, in practice, in combination with diets and throughout the whole day, all the food that you eat, it's very minimal.

But of course, I mean, I ride a bike that is only 9 kilos, but I might have actually 15 kilograms of overweight. So I could actually do with a much heavier bike, but I still want the fastest bike and the lightest bike. And so people want the best supplement. Does it make that much of a difference? I don't think so that much. Sitting upright while you eat or actually chewing well has also a huge effect on the rate of digestion and absorption. So, but these differences exist, but these— the differences are very small if you compare milk, whey, or egg protein. Oh, egg white as well. Egg is also great from amino acid composition and also digestion and absorption, it's great.

Dr. Rhonda Patrick: I want to shift back and talk about the protein source because we've talked about the animal source, we've talked about supplemental sources of protein from animal products, but there's also a large percentage of people that are vegetarian and vegan, don't consume any animal products. So maybe you can tell people a little bit about the differences between food sources, plant sources of protein versus animal sources of protein?

Dr. Luc van Loon: First, and then again, I have to make the difference between whole foods, protein isolates, and protein concentrates. So if you want to consume protein through plant-based foods, so beans, lettuce, nuts, whatever, is it's more difficult to get a certain amount of protein in. If you want to ingest 20 grams of protein through eating meat, 70 grams of meat.

If you want to get 20 grams of protein in by eating potatoes, you have to eat more than a kilogram of potatoes. So first of all, it's just more difficult to get the same amount of protein in if you actually consume it as whole foods. And then when you consume it as whole foods, most plant-based foods have antinutritional factors. So the capacity for you to extract that protein through your body is less. So the digestibility is lower. Those are the 2 issues when you, when you have plant-based foods. Now, nowadays, and much of the research has looked at the proteins that are actually in plant-based foods, extracted those proteins, and then assessed their capacity to stimulate muscle protein synthesis.

It has been done for some proteins like wheat protein, soy protein a lot, pea protein, about 5 different proteins that we and others have actually assessed. And then some of them actually, some of these studies show a lesser capacity to stimulate muscle protein synthesis when compared to an equivalent amount of mostly dairy protein. That might be attributed to the fact that there's less leucine, less essential amino acids, and sometimes most of the plant-based proteins are deficient in one or more specific amino acids. That's often methionine and lysine. The last 5 years we have been trying the protein extracts from pea and gluten and corn And actually, if we give in healthy subjects, we give 30 grams, which is quite a lot of protein, we don't see a difference with dairy protein.

So if you give sufficient protein, a protein extract where digestibility is high, there's not that much difference in muscle protein synthesis. However, if you take it from a plant-based food, then for an equivalent amount of protein, less of that protein becomes available. And that is, of course, something you have to compensate for a little bit.

Dr. Rhonda Patrick: So vegans who are interested in preserving and gaining muscle mass with their resistance-training programs can supplement with plant-based protein powder sources that will allow them, on a gram-for-gram basis, especially if it's a high enough dose, to gain the same muscle mass as someone using, let's say, animal-based protein supplements?

Dr. Luc van Loon: I think so.

So they don't necessarily have to take supplements, supplements is probably easier. They can also compensate for lesser quality by greater quantity, but then you have to consume a huge amount of food. And of course you improve the quality of your protein sources by having a very diverse variety of plant-based foods. So if you really know what you're doing from a nutrition perspective, dietetics perspective, then I think you're quite capable doing that on a vegan diet, but it's more difficult. And of course, if you start using plant-based protein isolates or plant-derived proteins, I should say, it gets easier.

Dr. Rhonda Patrick: You mentioned pea protein is what you looked at in your study and compared it to dairy, 30 grams and 30 grams, there was no difference in terms of skeletal muscle protein synthesis. What about— so is pea protein different from rice protein in terms of its amino acid composition? Is there a protein powder that's better perhaps for vegans that are interested in increasing their muscle mass?

Dr. Luc van Loon: We years ago, we looked at all the commercially available protein extracts, so plant-derived proteins. And then you see that some of them are actually low in leucine, but some, just as corn, is actually higher in leucine than most animal-derived proteins. So not all plant-based proteins are the same. Duh.

The deficiencies in lysine and methionine is also, one protein can be very deficient in methionine, the other one is actually deficient in lysine but not in methionine. So there's not one specific protein that I would say that one is the best, but you can mix up and blend different plant-based proteins that actually together have a very nice protein-balanced amino acid profile. Combinations are great. What we expected from our studies with the individual proteins, that they would actually show a lesser response, and that by adding some milk protein, we would actually compensate for that. But in all those proteins, like the pea protein, we actually did not find a lesser muscle protein synthetic response. But I do need to note that we did that with 30 grams.

Of a protein extract, so you don't have the digestibility issue.

Dr. Rhonda Patrick: You mentioned lysine and methionine. Maybe you can explain to people why those are also important. You mentioned leucine and how that stimulates mTOR, and that's important for muscle protein synthesis. But why is lysine and methionine important? And then maybe also, what would be a good combination of plant-based plant-sourced protein powders perhaps to get all those? Like you said, pea protein, is there something else in combination with pea that would cover all the bases?

Dr. Luc van Loon: One of the things, I mean, some amino acids may have stronger signaling properties, but of course, if you're trying to build a protein, you need all the building blocks, all the different building blocks, and that includes methionine and lysine, of course. So you need sufficient amounts of all the amino acids. Now, you can actually take blends, and we used a blend with three different plant-based proteins. That worked fine. But you also see that some combinations, for example, one is low in methionine and the other one low in lysine, actually make nice blends. And funny enough, if you start looking at those proteins, then you suddenly realize that all over the world people are consuming meals that actually have proteins that are very nicely complementary or matching.

And so when I saw those data the first time, I suddenly realized why a fajita actually has beans in it. So the wheat and the beans are actually a nice complementary amino acid mix. So it's really funny if you see that. Somewhere, people have actually noticed that or experienced that.

Dr. Rhonda Patrick: And then sprouting, I think also some of the— you can get sprouted quinoa, a source of protein, where it's getting rid of some of the, as you mentioned, antinutritional components, like the fiber matrix and, in some cases, other lectins that are sort of inhibiting some of the absorption of protein.

Dr. Rhonda Patrick: What about protein isolate versus concentrate? Is it better to consume protein isolate for higher protein?

Dr. Luc van Loon: I would prefer the product where the protein actually is in, so not even the isolate or the concentrate. But then if you're using a supplement and you want to take the pure protein, then you can take the isolate or the concentrate. The isolate is only the protein. The concentrate is basically the concentrated protein, so it still has other stuff. Like for milk protein concentrate, it still has lactose in it and still has some other stuff, some fat in there. So yeah, is one better than the other? It depends on what you're aiming for, what your nutrient targets are, basically.

Dr. Rhonda Patrick: If someone's interested in lower fat content and more protein content?

Dr. Luc van Loon: Yeah, then you would go for an isolate, of course. Protein isolate, okay.