People wondered about my explanation of microbiology and, after I read their comments, so did I! Fooducate asked me to rewrite, and this is the result, adapted for this blog.
The article had come about because I had questions “niggling” at me. I eat very little meat but lots of beans and whole grains. Here’s what I thought was true: Beans are an incomplete protein that needed to be completed to provide a protein that my body could use.
My questions were: What exactly is an incomplete protein? And what do I have to do to make sure it becomes complete? As my commenters and further research showed me, these questions were outdated and simplistic.
But let’s start at the beginning.
Where did the concept of incomplete and complete proteins come from?
In 1971 Frances Moore Lappé’s book, Diet for a Small Planet, became a huge bestseller. Her concern was world hunger, and she wanted to help poor people, who couldn’t access enough meat, get protein in their diets from plant-based foods. She believed that protein complementing was the answer.
This theory says that if a person combines two incomplete-protein foods in one meal—for example, rice and beans, then that person will be eating a complete protein just as if he or she was eating meat or dairy or eggs.
However, Lappé was not a scientist and the theory of protein complementing was later proven to be false. Lappé herself has acknowledged this.
Unfortunately, her book’s success meant that the theory has permeated our culture. For example, I “googled” complete protein and got some 12 million hits. In other words, people are still talking about incomplete and complete proteins, even if the terms no longer accurately explain what is really happening.
Scientists today talk about amino acids.
Thousands of different kinds of proteins exist in your body. While they have different functions, all are molecules that include the same amino acids. It’s the arrangement of these amino acids that determines the type and function of a protein.
There are two major categories of amino acids: nonessential amino acids, which are built by your body, and essential amino acids, which you can only get through food.
There are nine essential amino acids and their main purposes are
- Histidine—physical and mental growth
- Isoleucine—muscle production, blood formation
- Leucine—growth hormone production, tissue production and repair
- Lysine—bone development, hormone production
- Methionine—digestion of fats, removal of plaque
- Phenylalanine—brain processes and mood
- Threonine—monitoring of body proteins
- Tryptophan—mood, pain, and sleep regulation
- Valine—muscle production
Unlike fats, however, the essential amino acids aren’t stored in your body. Therefore, you need a daily supply of them, which you get through two sources: animal-based and plant-based foods.
Animal sources—meat, dairy, eggs—contain the essential amino acids organized in such a way that they deliver protein immediately—in “one bite,” so to speak. As commenter Christopher pointed out, it works this way because we’re animals too.
Plant-based food—beans, nuts, whole grains—also contains the essential amino acids but, because we’re not plants, they’re not organized in the appropriate ratio to deliver protein to us in “one bite.”
Your body does all the work.
When you digest foods that contain essential amino acids, these acids enter your blood stream. Not being a scientist, I don’t understand the cellular complexities of what happens next.
But what I do get is this: your body gets all the amino acids—essential and non-essential—to combine in the right ways, in the right places, and at the right times to build the different protein molecules it needs.
In other words, you do not have to consciously think about creating the right balance of essential amino acids at any one meal. Your body handles the “balance-making” for you.
Eat a wide variety of non-processed, plant-based foods every day.
As we all know, work that is well done is characterized by efficiency and effectiveness. Your body’s work is no different, but it needs the right tools.
Poor tools—highly processed foods and “white” foods, e.g., white bread—make it harder for your body to do its job well. These foods have not only been stripped of important nutrients, they also include high levels of sugar, fat, and salt—substances that can be dangerous to your health.
Whether you eat meat or not, your daily diet should also include plant-based foods which, in addition to essential amino acids, include many other nutrients vital to good health. Think fruits and vegetables, beans and legumes, nuts and seeds.
Please. Do your body a favor. Eat well and wisely!
- Amino Acids and Proteins, University of Cincinnati, 2004.
- Essential and Nonessential Amino Acids for Humans, University of Illinois at Chicago, date unknown.
- The Nutrition Source—Protein: Moving Closer to Center Stage Harvard School of Public Health, 2012
- The Chemistry of Amino Acids, University of Arizona, 2003.
- The Myth of Complementing Protein, J. N. Novick, Healthy Times, 2003
- Protein in Diet, MedlinePlus Medical Encyclopedia, 2004