If you live in the 21st century, you’ve most likely heard comparisons about plant protein vs animal protein. You’ve probably heard plant foods like quinoa, broccoli and soy are equally good sources of protein as animal foods, like eggs or steak. Sadly, protein myths like these are everywhere. Misinformed logic and bad Big Ag-fueled science permeates modern media. You have good reason to feel confused!
So is plant protein as good as animal protein?
In short, plant and animal foods are not equal when it comes to getting quality protein. Eat according to mainstream logic and you may unknowingly pay the price with your health.
Despite the info we’re constantly fed, getting quality protein is not simply about eating foods with lots of protein. Just because you can get relatively comparable grams of protein in a cup of quinoa as you can get in an egg or an ounce of beef does not mean quinoa and eggs or beef are comparable sources of protein. The nutrition rabbit hole goes deeper than that.
If you don’t willingly go down the rabbit hole and take informed action (read: on your plate), it’s highly likely your diet is deficient.
In the following article, I’ll unpack the myths and facts about plant and animal proteins, so you can make informed, empowered food and health choices.
What Protein Does for Your Body (Quality Protein, That Is)
Unlike fat or carbohydrates, your body can’t store protein.
Your body is in a constant process of using protein for countless bodily functions, making it super-important to eat enough quality protein every day, at every meal.
Basically, we need to eat a lot more protein than our bodies use. For every kilogram of body weight (2.2 pounds), our bodies use 0.33 grams of protein each day just for bare minimum maintenance.1
With a few hundred varieties, protein is one of the building blocks of life (where it all begins!). It’s responsible for some pretty important things, like, but not limited to
- making up our chromosomes (how we pass our traits on to our offspring)
- making up everything from bones, muscles, veins, arteries, skin, hair, nails, organs
- making up antibodies that help immunity
- making up enzymes that are responsible for countless chemical reactions in your body, including food digestion, and the breakdown of waste for elimination
- making up hormones when they combine with substances called sterols
- helping your body grow
- repairing tissues
- transporting oxygen around your body in red blood cells
- transporting fat around your body
- transporting cholesterol around your body, so it regulates the risk of heart disease
- providing satiety after we eat it.2
When you consider all the roles protein plays, you can understand why it’s so important to eat adequate quality protein.
To understand what determines protein quality–and who wins the epic battle of plant protein vs animal protein–we need to first take a look at how protein works.
Amino Acids and Protein Synthesis
Protein is made up of amino acids.
Your body can make some amino acids. There are twelve of these, called non-essential amino acids.
The eight amino acids your body can’t make are called essential amino acids; you can only get them from food. When you eat protein in foods, your body breaks down the protein into amino acids and rebuilds them into new combinations that form new proteins needed by your body to run.
If you don’t have enough protein in your diet and, more specifically, if you don’t have enough of all essential amino acids in your diet, your body can’t function properly.
It just so happens the amino acid profiles of some foods match up better than others, in terms of amounts and varieties, with the amino acid needs of the human body. And there is a difference between plant protein vs animal protein. Animal protein is superior. More on this shortly.
First, let’s get clear on how amazingly-ridiculously-insanely important it is that you get enough of all essential amino acids in certain amounts in your diet. Take, for example, protein’s role in cholesterol transport and liver detoxification.
Quality Protein Is Linked to Heart Health
Protein plays a pivotal role in the formation of apoproteins3, which transport cholesterol in your blood. If you don’t have all essential amino acids in the correct amounts, your body can’t properly transport cholesterol. For this reason, numerous studies have linked various levels of apoproteins to a potential cause of heart disease.4
Basically, the quality of protein you eat is integral to your body’s ability to manage any cholesterol (healthy and unhealthy varieties) that it makes.
If you’re not eating animal protein, you’re not getting adequate quality protein, and you’re not optimally supporting heart health.
Quality Protein Is Necessary for Healthy Detoxification
You also need quality protein for your body to properly detoxify. The amino acids that make up quality protein are required for the major pathways in the liver’s Phase II detoxification:
- Glutathione conjugation
- Sulfation and Sulfoxidation
In the 21st century, our ability to detoxify is all too often inhibited by all kinds of toxins our ancestors didn’t confront. This means any cleanse program that doesn’t pay attention to, or propagates misinformation about quality protein isn’t going to work very well. [Cough.] Juice cleanses. [Cough.]
Getting the right kind of protein–animal protein–becomes even more important the more you know about the way your body works.
Stop Only Focusing on Grams of Protein
“How much protein should I eat a day?” is a flawed question. It only focuses on the quantity of protein–the total number of grams of protein.
Unless you’re mainly subsisting on a diet of grains, bread, cereal, pasta, other flour-based products and sugar, you’re probably not severely deficient in terms of how much protein you’re consuming.
Whether we look at the Academy of Nutrition and Dietetics’s recommendations, or the cuisines of traditional cultures, getting just 15-30 percent of your daily calories from protein isn’t too hard. (Though don’t forget: you do have to eat protein every day because your body doesn’t store it.)
Remember how protein is made up of amino acids, both essential and nonessential?
Remember how you need to get—must get–essential amino acids from food because your body can’t make them?
Consider these reminders in the context of assertions from many health “experts,” who tell you you can get the same amount (grams) of protein from plant foods (beans, legumes (including soy), nuts, seeds, veggies, and to a lesser degree grains) as you can from animal foods (meat, eggs, dairy, fish and organ meats). While this may be the case, it’s also an incomplete, irrelevant point when it comes to supporting your body’s most basic functions.
When you compare plant protein to animal protein, you’re comparing apples and oranges.
Start Focusing on the Quality of Protein: NPU
Instead of only focusing on grams of protein, you also need to consider the quality of protein. The quality of protein is determined by the array and amounts of amino acids found in that protein, not the total number of grams of protein.
Technically, you can find most of the amino acids you need in both plant and animal foods, but the devil is in the details. And when it comes to plant protein vs animal protein, the details favor animal protein.
Protein quality is determined by what percentage of protein your body can actually absorb and use from a given food. This percentage is known as Net Protein Utilization (NPU).
Animal vs Plant Protein Absorption
Animal protein has the highest NPU. Animal protein also lacks the additional negative, counterproductive properties associated with eating enough plant foods to get the amino acids you need.
The shocking truth is that if you don’t have enough of all essential amino acids, your body can’t effectively use the essential amino acids you do eat.
The widespread, unchecked hype and misinformation that says plant protein sources are comparable to animal protein sources excessively focuses on grams of protein, as opposed to NPU (Net Protein Utilization).
We’re all different, with different stats (age, weight, activity levels), but that doesn’t change the fact that certain foods contain the ideal, highest levels of amino acids your body needs, and there are certain foods that simply can’t compare.
NPU: Protein Absorption Rates of Foods
Check out the Net Protein Utilization (NPU) of the following foods:
- 6-1/2 eggs have an NPU of 94%
- 5-1/2 cups of milk have an NPU of 86%
- 5 ounces of Swiss or cheddar cheese have an NPU of 82%
- 6.6 ounces of steak (beef) have an NPU of 75%
- 1 cup cooked brown rice has an NPU of 74%
- 1 cup cooked quinoa has an NPU of 68%
- 2 cups of soybeans have an NPU of 66%
- 2 cups of peanuts have an NPU of 56%
- 36 slices of whole wheat bread have an NPU of 53%
- 7.2 cups of dried beans and peas have an NPU of 34%.5,6,7,8
Plant Protein vs Animal Protein: A Case of Mistaken Equality
Basically, proteins from animal foods provide essential amino acids and tout a higher NPU that proteins from plant foods just plain can’t.
For this reason, we call animal proteins “complete” proteins.
Mother’s milk contains all the amino acids, in the precise amounts required by her baby (Nature knows!).
After mother’s milk, the best source of protein that has lots of the amino acids your body needs are eggs—whole eggs, none of this “whites only” crap. Nature put the egg and the yolk together for a reason and that reason is nutrient-dense and delicious (as you’ve learned, don’t worry about saturated fat).
Various Types of Meat
After eggs, your body loves all the plentiful essential amino acids in pork, then sources like beef, chicken, fish and dairy.9
(The Myth of) Rice and Beans
True, you can combine rice and beans to get a more ideal array of amino acids (again, we can measure it in a generalized way via NPU). That said, you would have to eat unreal amounts of these plant foods to achieve the amino acid levels your body needs, and that you could easily get from animal-sourced foods.
Again, to make matters worse, not getting enough of all essential amino acids on a daily basis puts you at risk for deficiency because you can’t effectively absorb each essential amino acid if even one is too low. Got plenty of seven of the eight essential amino acids? That one missing or deficient amino will jeopardize your body’s ability to properly absorb and use those seven you did get enough of.
Are you going to eat 14 to 21 cups of beans in a day (which is what 7.2 cups of dried beans makes when cooked), or maybe you could eat half the beans and 18 slices of bread instead?10 Not too realistic, huh?
(The Myth of) Quinoa
True, quinoa contains all the essential amino acids, but not at higher levels, and it also only contains 8 grams of protein in a cup (cooked), alongside a whopping 40 grams of carbs (only 5 of which are fiber, the other 35 are starch). Women of average weight would need to eat about 5-1/2 cups of quinoa per day to meet daily minimum protein needs of around 45 grams protein. That comes out to 192 grams of starchy insulin-spiking carbs total! Not really realistic or smart, is it?
More Problems with Plant Sources of Protein
Keep in mind: the above figures are simply mentioned for the sake of comparison. In ways not related to protein, plant-sourced foods like grains, legumes, beans and plant oils are still not nutrient-dense enough, and too high in other things (i.e. starch, antinutrients, inflammatory types of fats) your body doesn’t need or need much of.
Plus, soy is unhealthy for a number of reasons, and actually blocks your body’s ability to absorb protein11 (check out Chapter 6 of Eat Like a Fatass, Look Like a Goddess for more on this). Also, wheat isn’t ideal for many people, further making it an inferior source of protein (see Chapter 4).
Wanna be realistic and smart? Eat animal protein. (Yes, doing this can be done ethically, and in a way that is super-beneficial for the planet.)
Problems with Higher-NPU Plant Protein Powders
What about those vegan protein powders that combine protein from lots of different sources (grains, beans and legumes) to get as high of an NPU as possible?
In terms of nutrition: such a plant-based blend will never contain 100% of the essential amino acids at the doses you need. Allow me to repeat: regularly missing just one amino acid, or having too low an intake of any one amino can have a serious impact on your ability to properly assimilate all the others you might have in abundance. This will impact your health.
If you have to turn to science-y powders with a blend of ten-plus ingredients, you’re not doing something right—especially if those ten-plus ingredients can’t even give your body everything it needs.
In terms of ecology, these protein powders require quite a bit of resources to produce these more comprehensive amino acid profiles. Why?