Plant-Based Protein: Are Pea and Soy Protein Isolates Harmful?

Michael Greger M.D. FACLM · February 3, 2021 · Volume 52

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What are the different impacts of plant protein versus animal protein, and do the benefits of plant proteins translate to plant protein isolates?

Discuss

Transcript

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

So, are these plant-based burgers healthy or not? And the answer is…compared to what? Eating is kind of a zero-sum game; every food has an opportunity cost. I mean, every time we put something in our mouth, it’s a lost opportunity to put something even healthier in our mouth. So, if you want to know if something is healthy, you have to compare it to what you’d be eating instead. So, for example, are eggs healthy? Compared to a breakfast link sausage? Yes! But compared to oatmeal? Not even close. But look; sausage is considered a group 1 carcinogen. In other words, we know consumption of processed meat causes cancer. Each 50-gram serving a day––that’s a single breakfast link––was linked to an 18 percent higher risk of colorectal cancer. So, the risk of getting colorectal cancer eating one link a day is about the same as the increased risk of lung cancer you’d get breathing secondhand smoke all day living with a spoking spouse. So, compared to sausage, eggs are healthy, but compared to oatmeal, eggs are not.

So, when it comes to Beyond Meat and the Impossible Burger, yeah, they may be better in that they have less saturated fat, but, hey, you want less saturated fat? Plant-based meat alternatives are no match for unprocessed plant foods, such as beans or lentils. And a bean burrito or lentil soup could certainly fill the same culinary niche as a lunchtime burger. But if you are going to have some kind of burger, it’s easy to argue that the plant-based versions are healthier. There is a sodium issue, and it’s not that much, if any, lower in saturated fat, since they use coconut oil, which is basically just as bad as animal fat. There’s not much advantage on that front.

Though the total protein is similar across the board, does this matter? Is there any advantage to eating plant protein over animal protein? Let’s look at the association between animal and plant protein intake and mortality. In the twin Harvard cohorts, following more than 100,000 men and women over decades, “…after adjusting for other dietary and lifestyle factors, animal protein intake was associated with a higher risk [of] mortality, particularly [dying from cardiovascular disease], whereas higher plant protein intake was associated with [a] lower all-cause mortality”, meaning a lower risk of dying from all causes put together. So, “replacing animal protein of various origins with plant protein was associated with lower mortality”––especially if you’re replacing processed meat and egg protein, which were the worst. But when it comes to living a longer life, plant protein sources beat out each and every animal protein source. Not just better than bacon and eggs, but better than burgers, chicken, turkey, fish, and dairy protein.

Together with other studies, these “findings support the importance of protein sources for the long-term health outcome and suggest that plants constitute a preferred protein source compared [to] animal foods.” Why? Well, unlike animal protein, plant protein has not been associated with increased levels of the cancer-promoting growth hormone IGF-1, for example. Now, soy protein is similar enough to animal protein that at high enough doses, like eating two Impossible Burgers a day, you may bump your IGF-1. But the only reason we care about IGF-1 is cancer risk, and if anything, higher soy intake is associated with a decreased risk of cancer. For example, a recent systematic review and meta-analysis found that soy protein intake was associated with a decreased risk in breast cancer mortality; we’re talking “a 12 percent reduction in breast cancer death [associated with] each 5-gram-a-day increase in soy protein intake.” But the high soy groups in these studies were on the order of more than 16 grams a day, associated with a whopping 62 percent lower risk of dying from breast cancer. More than 10 grams of soy protein a day may be good, associated with cutting breast cancer mortality risk nearly in half, and getting more than 16 grams a day may be better, which is like one Impossible Burger a day. But we simply don’t know what happens at consumption levels far above that.

Plant protein has also been linked to lower blood pressure, reduced LDL cholesterol, and improved insulin sensitivity. No wonder “substitution of plant protein for animal protein has been related to a lower incidence of cardiovascular disease and type 2 diabetes.” Indeed, 21 different studies following nearly a half million people, and “high… animal protein intakes [were] associated with an increased risk of [type 2 diabetes], whereas [even just] moderate plant protein intake is associated with a decreased risk of [type 2 diabetes].” Okay, but these were just observational studies. They all tried to control for other dietary and lifestyle factors, but you can’t prove cause and effect, until you put it to the test.

The “Effect of Replacing Animal Protein with Plant Protein on [blood sugar] Control in Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.” Even just switching out about a third of your protein from animal to plant sources yielded significant improvements in long-term blood sugar control, fasting blood sugars, and insulin.

You can do the same thing looking at cholesterol. Here’s a systematic review and meta-analysis of randomized controlled trials on the effect of plant protein on blood fats. And indeed, swapping in plant protein for animal protein decreases LDL cholesterol, and this benefit occurs whether you start out at high cholesterol or low cholesterol, whether you’re swapping out dairy, or meat and eggs, and whether you’re swapping in soy or other plant proteins.

We’ve known about the beneficial effects of soy on cholesterol going back nearly 40 years, but other sources of plant protein can do it as well. Yeah, but we’re not swapping beans for beef. These products are mostly just isolated plant proteins, mostly pea protein isolate in the case of Beyond, and concentrated soy protein in the case of Impossible. If you just isolate out the plant proteins themselves are you still going to get benefits? Yes, surprisingly. Check it out.

Interestingly, the researchers concluded, that they did not ﬁnd a signiﬁcant difference between protein isolate products and whole food sources, “suggesting that the cholesterol-lowering effects are at least, in part, attributable to the plant protein itself rather than just the associated nutrients.” So, it’s not just because plant protein travels with fiber or less saturated fat. Plant proteins break down into a different distribution of amino acids; and so, it’s like if you give people arginine, an amino acid found more in plant foods, that alone can bring down people’s cholesterol. And even plant protein concentrates used in these products aren’t pure protein, retaining a few active compounds such as phytosterols and antioxidants, which also can have beneficial effects.

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Sources

Acknowledgements

Video production by Glass Entertainment

Motion graphics by Avocado Video

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

So, are these plant-based burgers healthy or not? And the answer is…compared to what? Eating is kind of a zero-sum game; every food has an opportunity cost. I mean, every time we put something in our mouth, it’s a lost opportunity to put something even healthier in our mouth. So, if you want to know if something is healthy, you have to compare it to what you’d be eating instead. So, for example, are eggs healthy? Compared to a breakfast link sausage? Yes! But compared to oatmeal? Not even close. But look; sausage is considered a group 1 carcinogen. In other words, we know consumption of processed meat causes cancer. Each 50-gram serving a day––that’s a single breakfast link––was linked to an 18 percent higher risk of colorectal cancer. So, the risk of getting colorectal cancer eating one link a day is about the same as the increased risk of lung cancer you’d get breathing secondhand smoke all day living with a spoking spouse. So, compared to sausage, eggs are healthy, but compared to oatmeal, eggs are not.

So, when it comes to Beyond Meat and the Impossible Burger, yeah, they may be better in that they have less saturated fat, but, hey, you want less saturated fat? Plant-based meat alternatives are no match for unprocessed plant foods, such as beans or lentils. And a bean burrito or lentil soup could certainly fill the same culinary niche as a lunchtime burger. But if you are going to have some kind of burger, it’s easy to argue that the plant-based versions are healthier. There is a sodium issue, and it’s not that much, if any, lower in saturated fat, since they use coconut oil, which is basically just as bad as animal fat. There’s not much advantage on that front.

Though the total protein is similar across the board, does this matter? Is there any advantage to eating plant protein over animal protein? Let’s look at the association between animal and plant protein intake and mortality. In the twin Harvard cohorts, following more than 100,000 men and women over decades, “…after adjusting for other dietary and lifestyle factors, animal protein intake was associated with a higher risk [of] mortality, particularly [dying from cardiovascular disease], whereas higher plant protein intake was associated with [a] lower all-cause mortality”, meaning a lower risk of dying from all causes put together. So, “replacing animal protein of various origins with plant protein was associated with lower mortality”––especially if you’re replacing processed meat and egg protein, which were the worst. But when it comes to living a longer life, plant protein sources beat out each and every animal protein source. Not just better than bacon and eggs, but better than burgers, chicken, turkey, fish, and dairy protein.

Together with other studies, these “findings support the importance of protein sources for the long-term health outcome and suggest that plants constitute a preferred protein source compared [to] animal foods.” Why? Well, unlike animal protein, plant protein has not been associated with increased levels of the cancer-promoting growth hormone IGF-1, for example. Now, soy protein is similar enough to animal protein that at high enough doses, like eating two Impossible Burgers a day, you may bump your IGF-1. But the only reason we care about IGF-1 is cancer risk, and if anything, higher soy intake is associated with a decreased risk of cancer. For example, a recent systematic review and meta-analysis found that soy protein intake was associated with a decreased risk in breast cancer mortality; we’re talking “a 12 percent reduction in breast cancer death [associated with] each 5-gram-a-day increase in soy protein intake.” But the high soy groups in these studies were on the order of more than 16 grams a day, associated with a whopping 62 percent lower risk of dying from breast cancer. More than 10 grams of soy protein a day may be good, associated with cutting breast cancer mortality risk nearly in half, and getting more than 16 grams a day may be better, which is like one Impossible Burger a day. But we simply don’t know what happens at consumption levels far above that.

Plant protein has also been linked to lower blood pressure, reduced LDL cholesterol, and improved insulin sensitivity. No wonder “substitution of plant protein for animal protein has been related to a lower incidence of cardiovascular disease and type 2 diabetes.” Indeed, 21 different studies following nearly a half million people, and “high… animal protein intakes [were] associated with an increased risk of [type 2 diabetes], whereas [even just] moderate plant protein intake is associated with a decreased risk of [type 2 diabetes].” Okay, but these were just observational studies. They all tried to control for other dietary and lifestyle factors, but you can’t prove cause and effect, until you put it to the test.

The “Effect of Replacing Animal Protein with Plant Protein on [blood sugar] Control in Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.” Even just switching out about a third of your protein from animal to plant sources yielded significant improvements in long-term blood sugar control, fasting blood sugars, and insulin.

You can do the same thing looking at cholesterol. Here’s a systematic review and meta-analysis of randomized controlled trials on the effect of plant protein on blood fats. And indeed, swapping in plant protein for animal protein decreases LDL cholesterol, and this benefit occurs whether you start out at high cholesterol or low cholesterol, whether you’re swapping out dairy, or meat and eggs, and whether you’re swapping in soy or other plant proteins.

We’ve known about the beneficial effects of soy on cholesterol going back nearly 40 years, but other sources of plant protein can do it as well. Yeah, but we’re not swapping beans for beef. These products are mostly just isolated plant proteins, mostly pea protein isolate in the case of Beyond, and concentrated soy protein in the case of Impossible. If you just isolate out the plant proteins themselves are you still going to get benefits? Yes, surprisingly. Check it out.

Interestingly, the researchers concluded, that they did not ﬁnd a signiﬁcant difference between protein isolate products and whole food sources, “suggesting that the cholesterol-lowering effects are at least, in part, attributable to the plant protein itself rather than just the associated nutrients.” So, it’s not just because plant protein travels with fiber or less saturated fat. Plant proteins break down into a different distribution of amino acids; and so, it’s like if you give people arginine, an amino acid found more in plant foods, that alone can bring down people’s cholesterol. And even plant protein concentrates used in these products aren’t pure protein, retaining a few active compounds such as phytosterols and antioxidants, which also can have beneficial effects.

Please consider volunteering to help out on the site.

Video production by Glass Entertainment

Motion graphics by Avocado Video

Doctor's Note

This is the third video in a series on plant-based meats. If you missed the first two, see The Environmental Impacts of Plant-Based Meat Substitutes and Are Beyond Meat and the Impossible Burger Healthful?

Still to come:

If you don’t want to wait for all nine of the videos in this series to roll out on NutritionFacts.org, you can get them right now in a digital download from my webinar a few months ago.

If you haven't yet, you can subscribe to our free newsletter. With your subscription, you'll also get notifications for just-released blogs and videos. Check out our information page about our translated resources.

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