You, Protein, and Amino Acids

This is what an amino acid can look like.

In March, I posted an article called “What’s an Incomplete Protein?” This article was also posted on the Fooducate blog where it came in for some criticism, and rightly so.

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 As my commenters and further research showed me, these questions were outdated and simplistic.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!


14 thoughts on “You, Protein, and Amino Acids

  1. You do need to eat that daily variety from different plant food groups, though, which is why the whole “complete” and “incomplete” phrasing has stuck around. Your internal amino acid “pool” sticks around for about 3 days, but it’s still better to have intake of all the essential amino acids daily. I’m emphasizing the different food groups, rather than just variety. You can eat a wide variety of fruit and nuts and still be missing essential amino acids.

    • It was the concept of the “pool” that bothered a number of readers on the Fooducate site. Maybe a bus travelling around our bloodstreams would have been a better metaphor, i.e., carrying the different amino acids around our body. Re the food groups, point taken and people need to eat vegetables and grains as well. But it’s the vegetarians who, by missing meat, need to be well informed about plant-based proteins. As for the rest of us, you’re right…a good, balanced diet should do it.

      • Hmm, interesting aspect to object to. My grad school nutrition classes used the “pool” analogy and I always liked it. Accessible body stores might be a better way to phrase it technically, but what an awkward way to phrase it for general conversation.

        Anyway, I’m enjoying your explorations of the science of nutrition.

  2. This is a great post. As a vegan (mostly vegan) I get so tired of the “how do you get enough protein” question. People aren’t very educated about food in our culture (US), and it’s a shame really.

    • Thanks for visiting and commenting. And it is unfortunate that the Lappe book made such an deep impression…it’s now part of the popular culture so people see you as eating lots of incomplete proteins as opposed to eating in a healthful way.

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