What comes to mind when you hear the word “protein?” If you were to say meat, you’re not alone. Most of us have been conditioned to equate protein with animal-based food.
But did you know that at least 14% of the total calories of every plant are protein? Or how about that a cup of cooked oatmeal offers as much protein as an egg, and per calorie, spinach is about equal to chicken and fish?
Vegetables are just as veritable a source of protein as animals, but there seems to be a lingering concern about the perceived quality of plant-based proteins. And this has led many to believe that plant proteins rank much lower on the nutritional ladder than proteins derived from foods like poultry, eggs and steak. But this is hardly the case.
To better understand the common misperceptions of plant-based proteins, let’s start with the basics.
WHAT IS PROTEIN?
Proteins, along with carbohydrates and fats are macronutrients — the main components of our diet and that our bodies require in relatively large amounts for normal function and good health. Vitamins and minerals are also important parts of the puzzle, but these are needed in much smaller quantities, which is why we refer to them as micronutrients.
Proteins are made up of smaller building blocks called amino acids, strung together in chains. There are 20 different amino acids, nine of which are considered essential because our bodies cannot produce them naturally. These essential amino acids must be obtained through diet.
Each source of protein has a different arrangement of hundreds or even thousands of amino acids. During digestion, our bodies break down the protein molecules then put them back together to create new and different proteins based on what our systems need.
When we consume proteins that have a similar amino arrangement to those in our own body, we synthesize that protein very efficiently. Animal-based proteins, not surprisingly, are much more similar to our protein structure than plant-based proteins, so our body is able to break them down more readily and rapidly. This is where the concept of protein “quality” comes into play — the more efficient a protein can be broken down, the higher “quality” we assume the protein is.
QUALITY DOES NOT EQUAL GOOD HEALTH
Quality equates to the efficiency with which food proteins are used to promote growth. And this would be all well and good if the most efficient proteins also equaled the greatest health. But this is just not the case. In fact, there have been a number of epidemiological studies and clinical research that have shown exactly the opposite to be true, most notably, the China Study.
A massive collaboration between Cornell University, Oxford University and the Chinese Academy of Preventive Medicine, the China Study is the most comprehensive study of diet, lifestyle and disease that has ever been conducted in the history of biomedical research. Over the course of the intensive study, researchers surveyed a wide range of diseases and diet and lifestyle factors across rural China and Taiwan, and eventually produced more than 8,000 statistically significant associations between various dietary factors and disease.
The study also showed that even relatively small intakes of animal-based foods were associated with adverse effects. And what’s more, the study revealed that the source of animal protein didn’t matter. Whether it came from a lean pork chop, egg whites, or a glass of whole milk, the results were all the same.
THE SURPRISING BENEFITS OF PLANT PROTEINS
Yet what made the China Study particularly remarkable was what it revealed about plant-based proteins. The scientists found that by removing animal protein from the equation and replacing it with plant-based protein, they created the opposite effect of the aforementioned points. In fact, not only did the plant proteins prevent degenerative disease, they also, in many cases, reversed it, even in instances where there was a genetic predisposition factor involved.
What it really comes down to is that eating animals is a significantly different nutritional experience from eating plants. On top of the aforementioned, plant-based foods have substantially more antioxidants, fiber and minerals than animal-based foods and significantly less cholesterol and saturated fat. Plant-based foods also tend to be alkaline forming, which can help your body combat inflammation, reduce stress and protect bone health.
THE PRESSING IMPORTANCE OF NUTRITION
While eating tons of animal-based proteins is not the sole reason people develop chronic health issues, it is a major factor, especially right here in the United States. At 200 pounds of meat per person per year, the average consumption of meat in America is higher than anywhere else in the world. And it’s hurting our national health. We spend more on our health care than any other country, yet Americans have twice the obesity rate, twice the diabetes rate, and nearly three times the cancer rate as the rest of the world.
This is why the need for change is as urgent as ever. Granted, many will be reluctant to go against popular opinion, which values animal-based proteins as the purest and highest-quality proteins, but the science and statistics should be reason enough to doubt the status quo. Nutrition undoubtedly has a very strong effect on our health and arguably, our likelihood of developing chronic disease. And the China Study, as comprehensive in its design as it was in its findings, delivered a very clear message — that we can maximize our health and well-being simply by choosing to eat the right foods.
So start small. Take steps in the right direction. Because the choices you make when it comes to what’s on your plate may be the choices that save your health.
Recently, I was teaching a nutrition class and describing the adequacy of plant-based diets to meet human nutritional needs. A woman raised her hand and stated, “I’ve read that because plant foods don’t contain all the essential amino acids that humans need, to be healthy we must either eat animal protein or combine certain plant foods with others in order to ensure that we get complete proteins.”
I was a little surprised to hear this, since this is one of the oldest myths related to vegetarianism and was disproved long ago. When I pointed this out, the woman identified herself as a medical resident and stated that her current textbook in human physiology states this and that in her classes, her professors have emphasized this point.
I was shocked. If myths like this abound not only in the general population but also in the medical community, how can anyone ever learn how to eat healthfully? It is important to correct this misinformation, because many people are afraid to follow healthful, plant-based, and/or total vegetarian (vegan) diets because they worry about “incomplete proteins” from plant sources.
How did this “incomplete protein” myth become so widespread?
No Small Misconception
The “incomplete protein” myth was inadvertently promoted and popularized in the 1971 book, Diet for a Small Planet, by Frances Moore Lappé. In it, the author stated that plant foods are deficient in some of the essential amino acids, so in order to be a healthy vegetarian, you needed to eat a combination of certain plant foods at the same time in order to get all of the essential amino acids in the right amounts. It was called the theory of “protein complementing.”
Lappé certainly meant no harm, and her mistake was somewhat understandable. She was not a nutritionist, physiologist, or medical doctor; she was a sociologist trying to end world hunger. She realized that converting vegetable protein into animal protein involved a lot of waste, and she calculated that if people ate just the plant protein, many more could be fed. In the tenth anniversary edition of her book (1981), she retracted her statement and basically said that in trying to end one myth—the inevitability of world hunger—she had created a second one, the myth of the need for “protein complementing.”
In this and later editions, she corrects her earlier mistake and clearly states that all plant foods typically consumed as sources of protein contain all the essential amino acids, and that humans are virtually certain of getting enough protein from plant sources if they consume sufficient calories.
Amino Acid Requirements
Where did the concept of essential amino acids come from and how was the minimum requirement for essential amino acids derived? In 1952, William Rose and his colleagues completed research to determine the human requirements for each of the eight essential amino acids. They set the minimum amino acid requirement equal to the greatest amount required by any single person in their study. Then to arrive at the recommended amino acid requirement, they simply doubled the minimum requirements. This recommended amount was considered a definite safe intake.
Today, if you calculate the amount of each essential amino acid provided by unprocessed plant foods and compare these values with those determined by Rose, you will find that any single whole natural plant food, or any combination of them, if eaten as one’s sole source of calories for a day, would provide all of the essential amino acids and not just the minimum requirements but far more than therecommended requirements.
Modern researchers know that it is virtually impossible to design a calorie-sufficient diet based on unprocessed whole natural plant foods that is deficient in any of the amino acids. (The only possible exception could be a diet based solely on fruit).
Pride and Prejudice
Unfortunately, the “incomplete protein” myth seems unwilling to die. In an October 2001 article on the hazards of high-protein diets in the medical journal Circulation, the Nutrition Committee of the American Heart Association wrote, “Although plant proteins form a large part of the human diet, most are deficient in one or more essential amino acids and are therefore regarded as incomplete proteins.”1 Oops!
Medical doctor and author John McDougall wrote to the editor pointing out the mistake. But in a stunning example of avoiding science for convenience, instead of acknowledging their error, Barbara Howard, Ph.D., head of the Nutrition Committee, replied on June 25, 2002 to Dr. McDougall’s letter, stating (without a single scientific reference) that the committee was correct and that “most [plant foods] are deficient in one or more essential amino acids.” Clearly, the committee did not want to be confused by the facts.
Maybe you are not surprised by this misconception in the medical community, but what about the vegetarian community?
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