Wherein I Learn What Protein Is…

I had the lucky chance to be able to share coffee with an insightful group of people last week, most of them dietitians, to talk about school food.

At one point in our conversation I admitted that I didn’t know what protein is.

Other than having a vague sense that I need protein to survive, and that I can get it by eating things like meat – he takes a moment to Google “sources of protein” – eggs, tofu, nuts, and beans, I had no idea why I might need protein to survive. Nor what eating more, or less, or better, or worse sources of protein would do to me.

Fortunately my dietitian friends greeted my admission of ignorance kindly; indeed one of them suggested that perhaps knowing about the ins and outs of protein might be a lot less important than simply understanding what eating “whole foods” is about.

But, regardless of their kindnesses, I decided I needed to learn about protein.

Fortunately I had, on my recent trip to London, come across the book Gut: The Inside Story of Our Body’s Most Underrated Organ in the London Review Book Shop and purchased a copy. While the book isn’t about protein specifically – it has far more to say about the mechanics of poop – it does helpfully provide a well-worded short course on the fundamentals of food. And it has this to say about protein:

Having examined carbohydrates and fats, there is just one more nutritional building block to consider. It is probably the least familiar: amino acids. It seems strange to imagine, but both tofu, with its neutral-to-nutty taste, and salty, savory meat are made up of lots of tiny acids. As with carbohydrates, these tiny building blocks are linked in chains. This is what gives them their different taste and a different name: proteins.

Digestive enzymes break down these chains in the small intestine and then the gut wall nabs the valuable components. There are twenty of these amino acids and an infinite variety of ways they can be linked to form proteins. We humans use them to build many substances, not the least of which is our DNA, the genetic material contained in every new cell we produce every day. The same is true of other living things, both plants and animals. That explains why everything that nature produces that we can eat contains proteins.

That’s exactly the concise explanation of what protein is that I needed: it allowed me to take the disconnected bits of protein trivia I’ve been floating through all my life and to start to bind them together.

It also makes eating protein sound pretty important to success in life.

This is only one of the wonderful things I learned from the book Gut. Beyond the aforementioned poop mechanics, I learned about fats and carbohydrates, about the immune system, about saliva, about what the appendix does. And I’m only halfway through the book. It’s entertainingly written, well illustrated, and, as with the treatise on protein, provides just the right amount of information to allow one to start making sense of how food and body work together to support life.

As the story of protein continues in the book, it gets even more interesting:

Plants construct different proteins than animals, and they often use so little of a given amino acid that the proteins they produce as known as incomplete. When our body tries to use these to make the amino acids it needs, it can continue to build the chain only until one of the amino acids runs out. Half-finished proteins are then simply broken down again, and we excrete the tiny acids in our urine or recycle them in our body.

After reading that paragraph I went from simple connecting-the-dots to a sudden and profound shift in my world view:

When we eat plants and animals we are simply taking the stuff they used to make themselves, and using it to make ourselves.

That may be self-evident to you, but this revelation has just completely rocked my world.

I’d simply never thought of plants and animals this way, and never connected the notions of eating, plants & animals, and protein all together in a systematic way.

Amino acid swapping. That’s what it’s all about. That is amazing.

I’m so glad I admitted I didn’t know what protein was, and that I set out to correct that.


Oliver Rukavina's picture
Oliver Rukavina on June 8, 2016 - 15:30

It's like any Vegetarian they think you are "OH They have MEAT and Vegetables!" and Vegetarians say "Oh We do not eat meat and we do eat vegetables!"

Oliver B's picture
Oliver B on June 8, 2016 - 16:52

I am so happy for you, Peter. Seriously, I'm that much of a geek and so committed to science literacy. In fact, even though I know what protein is in PhD detail, I had a similar epiphany lately about eating being a process of using the biochemical constituents of one organism to build more of another one that's digesting it, that it's categorically a different approach to growth than photosynthesis, and that it's kind of incredible that it's even possible. BTW, those explanations are strictly inaccurate and a little misleading, in that they suggest proteins are inherently acidic, being "made of amino acids." Amino acids cease to be acids in the chemical binding process that links them together in a chain that we call a protein, or a protein molecule. The chains have pendant clusters of atoms that can be acidic or basic or oily-neutral. That's why different enzymes are able to catalyze different kinds of chemical reactions, and why some proteins bury parts of themselves in the oily membrane that surrounds a cell--because there are oil-loving segments of their chains and water-loving parts. Each kind of amino acid has a different pendant and that's what distinguishes them from one another. If you don't have all 20 kinds, your body can't build and maintain everything it needs to.

Oliver B's picture
Oliver B on June 8, 2016 - 16:54

Strictly a protein is a chain of "amino acid residues." It's made from amino acids and made *of* amino acid residues.

Carla Gilders's picture
Carla Gilders on June 9, 2016 - 02:37

Diet for a Small Planet was all about the incomplete protein of plants and combining amino acids in things like rice and beans to create complete proteins. Who knew???

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