Protein in Context
We hear quite a lot about protein nowadays. Can you get enough protein from plants? If so, why do people need animal protein? Couldn't we use the grain fed to them to end world hunger? This post aims to answer these questions. The truth of the matter is that advocates for animal agriculture and advocates of plant-based diets want the same thing. Our common goal is to, "Simultaneously optimize the food supply, health, environmental, and social justice outcomes for the world's population,"(1). In other words, our goals are the same. We merely tend to differ in how to get there.
To answer the first question, we must examine animal proteins and plant proteins, and their similarities and differences. Opponents of animal agriculture often focus too much on gross calorie/protein intake and output values without considering the finished product. In short, too much attention is paid to feed conversion ratios, not WHAT is being converted. Animals, especially ruminants like cows and sheep, have an amazing ability to take low-quality protein sources and convert them into higher quality proteins through the process of fermentation. In other words, they can utilize low value materials that are inedible or unpalatable for people. We call these low value materials "by-products." Examples of by-products include soybean meal, cottonseed meal, dried distillers grains, and algae meal. Of these by-products, only the soybean is able to be digested by humans. However, soybean meal has become increasingly less and less popular among farmers and feed companies alike because of the high cost associated with it. Quite simply, it is cheaper to feed products like dried distillers grains (a by-product of beer making) than it is to feed soybean meal. Since dried distillers grains are a lower quality source of protein than soy, it saves farmers money to feed this to animals, since animals convert it into a better quality protein. In contrast, plant proteins are not always high quality, and do not contain a complete amino acid profile (meaning they are not complete proteins). People must consume all the essential amino acids they need in order to prevent protein deficiency, and meat is an easily digestible source of complete protein. Opponents of animal agriculture argue, correctly, that since different plants have different amino acid profiles, all you must do to obtain what you need is combine different protein sources together. For example, beans are not a complete protein by themselves, and neither is rice. Combine them, however, and you get a complete protein source because beans contain the amino acids rice doesn't have, and rice contains the amino acids beans don't have. So technically, you can consume complete proteins without including meat in your diet. So far, those who swear by a plant based diet are correct. What many of them don't realize, however, is that some sources of protein do not turn loose of their amino acids as easily as others, and this means people must consume a higher quantity of these foods to get all the amino acids they need. The digestibility of certain foods is measured by a DIAAS (Digestible Indispensable Amino Acid) score. A DIAAS score measures the capacity of a protein source to meet the requirements for all of the indispensable (aka essential) amino acids. It is a percent, and is calculated by dividing the mg of DIAA (digestible indispensable amino acids) in a fecal test by the mg of DIAA in the reference sample, pre-digestion. This quotient is multiplied by 100 to give a percent digestibility. A DIAAS score greater than 100 means the protein supplies more than the required amount of the most limiting amino acids, and a DIAAS score of less than 100 means the protein source supplies less than the required amount of the most limiting amino acids, and therefore you must consume more of it to get enough in your system, no matter how much is found in the food pre-digestion.
This is problematic for the proponents of a plant-based diet. While you can theoretically obtain all the amino acids you need by eating enough plants that contain the amino acids you need, you have to eat MORE of them. Keeping in mind that 100 is the minimum DIAAS score for complete protein absorption, consider the following bar graph.
As you can see, the only thing that comes close to animal protein in terms of digestibility is soy. Even then, a single serving of unsweetened soy milk has only 7 grams of protein in it (2). In contrast, a serving of 85% lean, grass-fed beef boasts 23 grams of protein(3). This means you would need to drink more than three cups of soy milk to get the same amount of protein as you'd get from 4oz of ground beef. Since the recommended daily protein intake of an adult man is 56 grams (4), you'd need to drink EIGHT FULL CUPS of unsweetened soy milk to reach your recommended daily (complete)protein intake. Drink sweetened soy milk, and you pile on the calories in the form of added sugar. Eight cups of Silk Original soy milk is a whopping 880 calories (5). Getting your recommended daily intake of protein from ground beef only costs you just over 448 calories, assuming my math is correct. And you'll get more out of it because it's more easily digested. But that's just soy. What happens when the protein source isn't as easily digested as soy? How much do you have to eat to even compare to meat? I'm sure you've all seen this picture floating around:
Let's debunk that claim that broccoli is higher in protein, shall we? (And for the record, I'm not hating on broccoli. That stuff is flat out amazing for you because of all the vitamins and minerals it contains. Seriously, folks. Eat your veggies). Just how much broccoli does it take to make 100 calories? One cup of chopped, raw broccoli is 30 calories (6). This means it takes 3.3 cups of broccoli to make 11.1 grams of crude protein. This means you'd need to eat 5 WHOLE CUPS of broccoli to reach your recommended daily intake. But wait! There's more! That's CRUDE protein. When you adjust it according to its DIAAS score (61.3) and do the math, your body only absorbs 6.8 grams of protein out of that 100 calories. The rest is expelled as waste. That's just 2.04 grams of digested protein PER CUP. To reach your recommended daily intake of amino acids via broccoli, you'd need to eat 27 WHOLE CUPS OF BROCCOLI. I doubt I could choke down four. Compare that to the ground beef example used above, and you only have to eat 8.7 ounces of beef to reach your dietary intake in crude protein (the actual number would be less than that when you adjust for the DIAAS score). That's much more reasonable. Take a look at that bar graph and tell me: do you really want to see the math for SPINACH?
So technically, you can get all the protein you need from plants, as long as you eat the right ones (like soy), but animal protein certainly helps you, in that you don't have to eat as much of it. You can do a plant-based diet properly, but you have to adjust for the DIAAS score to make sure your calculations on how much you need are correct. That's why animal proteins are incredibly convenient, especially for impoverished nations like those in Africa. Good luck growing soy in the arid country of Mali (8). Instead, these people need animal products because, as discussed earlier, animals can convert low-quality proteins like grass and brush into the complete proteins (meat and milk) these people need to survive. Those who propose that the solution is to simply give them our leftover food crops are the cruelest of all. You might as well just look into the eyes of a starving child and say, "Let them eat cake." Feeding them the scraps of developed nations is wrong and sick. The simple truth is that these people NEED animal protein to get adequate nutrition. They can't subsist on incomplete proteins. So in the interest of fixing world hunger, I propose that we teach them better ways to raise animals, and develop GMO crops that will grow in their areas of the world.
In the meantime, those in America and other developed countries can rest easy, knowing they have the freedom to choose what they want to eat. That's AGmazing!
To answer the first question, we must examine animal proteins and plant proteins, and their similarities and differences. Opponents of animal agriculture often focus too much on gross calorie/protein intake and output values without considering the finished product. In short, too much attention is paid to feed conversion ratios, not WHAT is being converted. Animals, especially ruminants like cows and sheep, have an amazing ability to take low-quality protein sources and convert them into higher quality proteins through the process of fermentation. In other words, they can utilize low value materials that are inedible or unpalatable for people. We call these low value materials "by-products." Examples of by-products include soybean meal, cottonseed meal, dried distillers grains, and algae meal. Of these by-products, only the soybean is able to be digested by humans. However, soybean meal has become increasingly less and less popular among farmers and feed companies alike because of the high cost associated with it. Quite simply, it is cheaper to feed products like dried distillers grains (a by-product of beer making) than it is to feed soybean meal. Since dried distillers grains are a lower quality source of protein than soy, it saves farmers money to feed this to animals, since animals convert it into a better quality protein. In contrast, plant proteins are not always high quality, and do not contain a complete amino acid profile (meaning they are not complete proteins). People must consume all the essential amino acids they need in order to prevent protein deficiency, and meat is an easily digestible source of complete protein. Opponents of animal agriculture argue, correctly, that since different plants have different amino acid profiles, all you must do to obtain what you need is combine different protein sources together. For example, beans are not a complete protein by themselves, and neither is rice. Combine them, however, and you get a complete protein source because beans contain the amino acids rice doesn't have, and rice contains the amino acids beans don't have. So technically, you can consume complete proteins without including meat in your diet. So far, those who swear by a plant based diet are correct. What many of them don't realize, however, is that some sources of protein do not turn loose of their amino acids as easily as others, and this means people must consume a higher quantity of these foods to get all the amino acids they need. The digestibility of certain foods is measured by a DIAAS (Digestible Indispensable Amino Acid) score. A DIAAS score measures the capacity of a protein source to meet the requirements for all of the indispensable (aka essential) amino acids. It is a percent, and is calculated by dividing the mg of DIAA (digestible indispensable amino acids) in a fecal test by the mg of DIAA in the reference sample, pre-digestion. This quotient is multiplied by 100 to give a percent digestibility. A DIAAS score greater than 100 means the protein supplies more than the required amount of the most limiting amino acids, and a DIAAS score of less than 100 means the protein source supplies less than the required amount of the most limiting amino acids, and therefore you must consume more of it to get enough in your system, no matter how much is found in the food pre-digestion.
This is problematic for the proponents of a plant-based diet. While you can theoretically obtain all the amino acids you need by eating enough plants that contain the amino acids you need, you have to eat MORE of them. Keeping in mind that 100 is the minimum DIAAS score for complete protein absorption, consider the following bar graph.
As you can see, the only thing that comes close to animal protein in terms of digestibility is soy. Even then, a single serving of unsweetened soy milk has only 7 grams of protein in it (2). In contrast, a serving of 85% lean, grass-fed beef boasts 23 grams of protein(3). This means you would need to drink more than three cups of soy milk to get the same amount of protein as you'd get from 4oz of ground beef. Since the recommended daily protein intake of an adult man is 56 grams (4), you'd need to drink EIGHT FULL CUPS of unsweetened soy milk to reach your recommended daily (complete)protein intake. Drink sweetened soy milk, and you pile on the calories in the form of added sugar. Eight cups of Silk Original soy milk is a whopping 880 calories (5). Getting your recommended daily intake of protein from ground beef only costs you just over 448 calories, assuming my math is correct. And you'll get more out of it because it's more easily digested. But that's just soy. What happens when the protein source isn't as easily digested as soy? How much do you have to eat to even compare to meat? I'm sure you've all seen this picture floating around:
Let's debunk that claim that broccoli is higher in protein, shall we? (And for the record, I'm not hating on broccoli. That stuff is flat out amazing for you because of all the vitamins and minerals it contains. Seriously, folks. Eat your veggies). Just how much broccoli does it take to make 100 calories? One cup of chopped, raw broccoli is 30 calories (6). This means it takes 3.3 cups of broccoli to make 11.1 grams of crude protein. This means you'd need to eat 5 WHOLE CUPS of broccoli to reach your recommended daily intake. But wait! There's more! That's CRUDE protein. When you adjust it according to its DIAAS score (61.3) and do the math, your body only absorbs 6.8 grams of protein out of that 100 calories. The rest is expelled as waste. That's just 2.04 grams of digested protein PER CUP. To reach your recommended daily intake of amino acids via broccoli, you'd need to eat 27 WHOLE CUPS OF BROCCOLI. I doubt I could choke down four. Compare that to the ground beef example used above, and you only have to eat 8.7 ounces of beef to reach your dietary intake in crude protein (the actual number would be less than that when you adjust for the DIAAS score). That's much more reasonable. Take a look at that bar graph and tell me: do you really want to see the math for SPINACH?
So technically, you can get all the protein you need from plants, as long as you eat the right ones (like soy), but animal protein certainly helps you, in that you don't have to eat as much of it. You can do a plant-based diet properly, but you have to adjust for the DIAAS score to make sure your calculations on how much you need are correct. That's why animal proteins are incredibly convenient, especially for impoverished nations like those in Africa. Good luck growing soy in the arid country of Mali (8). Instead, these people need animal products because, as discussed earlier, animals can convert low-quality proteins like grass and brush into the complete proteins (meat and milk) these people need to survive. Those who propose that the solution is to simply give them our leftover food crops are the cruelest of all. You might as well just look into the eyes of a starving child and say, "Let them eat cake." Feeding them the scraps of developed nations is wrong and sick. The simple truth is that these people NEED animal protein to get adequate nutrition. They can't subsist on incomplete proteins. So in the interest of fixing world hunger, I propose that we teach them better ways to raise animals, and develop GMO crops that will grow in their areas of the world.
In the meantime, those in America and other developed countries can rest easy, knowing they have the freedom to choose what they want to eat. That's AGmazing!
Sources
(1) Sabate and Soret, American Journal of Clinical Nutrition 2014
(2) http://www.mydietmealplanner.com/calorie-counter/beverages/soy-milk/unsweetened-soy-milk.html
(3) http://oregongrassfed.com/content/faq-nutition
(4) http://www.sciencedirect.com.ezproxy.library.tamu.edu/science/article/pii/S0002822302903469
(5) https://silk.com/products/original-soymilk
(6) http://www.baumanfarms.com/blog/tag/vegetable-growing-for-kids/
(7) Texas A&M Agrilife Research
(8) http://answersafrica.com/top-10-poorest-countries-in-africa.html
(9) http://jn.nutrition.org/content/early/2014/11/26/jn.114.195438.short?rss=1
(10) http://www.fao.org/ag/humannutrition/35978-02317b979a686a57aa4593304ffc17f06.pdf
I'm a full-time college student at Texas A&M University, where I'm in the process of getting my Animal Science degree, with eventual aspirations to go to law school and work as a consulting lawyer for agriculture corporations. I grew up around animals, and currently manage an operation that breeds show-quality boer goats for 4H and FFA exhibitors. My family also raises commercial cattle in south Texas.
I'm a full-time college student at Texas A&M University, where I'm in the process of getting my Animal Science degree, with eventual aspirations to go to law school and work as a consulting lawyer for agriculture corporations. I grew up around animals, and currently manage an operation that breeds show-quality boer goats for 4H and FFA exhibitors. My family also raises commercial cattle in south Texas.
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