This is a great question, if it’s something you’re wondering. However, before you can really learn the answer to this, it’s necessary to go over a few other things first. Those include how proteins are made up of two different kinds of amino acids, as well as how those acids work together to form two different kinds of proteins.
What are amino acids?
These are specific compounds that form proteins. There are two kinds; the first is essential amino acids, and the second is nonessential amino acids.
Essential amino acids are the kind that the human body has to get from dietary sources alone, namely food and beverage. This is because the human body either can’t produce these on its own from other parts of the diet, or it just can’t make enough of them on its own to supply itself. Nine different amino acids are thought to be essential. If you want a tongue-twister, their names are valine, threonin, histidine, leucine, lysine, methionine, isoluecine, phenylanine, and the annual Thanksgiving talking point, tryptophan.
Nonessential amino acids have equally trippy names, including tyrosine, serine, proline, glycine, glutamine, glutamic acid, cystine, aspartic acid, asparagine, arginine, and alanine. These don’t have to be consumed through dietary sources, since the human body can synthesize them on its own using various components from foods consumed.
As you can see, some proteins are necessary for full health and wellness, whereas others aren’t. Is this where complete proteins come into play? Yes! A complete protein is any food source that has all nine of the essential amino acids. Soy accomplishes this, as do many animal products, like dairy, eggs, poultry, fish, and meat. Even some fruits and veggies do it, like bananas, although their protein levels are usually far too low to make them good sources.
Does this mean that incomplete proteins don’t have all the essential amino acids?
You guessed right. Incomplete proteins account for most fruits, veggies, legumes, and grains.
This is where the concept of complementary protein nutrition comes into play. Even if some foods don’t have all the essential amino acids within them, that doesn’t mean you can’t enjoy them. You likely rarely eat only one food for a whole meal, so it’s possible to pair up complementary protein sources. When you pair two or more of the right incomplete proteins together, you get complete proteins once you clean your plate and the food is all together in your digestive system.
A very common and practical example of this is beans and rice, which pairs the incomplete proteins of grains and rice into a complementary protein in total. Peanut butter on either wheat bread or with oatmeal is another simple solution.
Hummus with pita bread, tofu with stir-fried veggies on rice, lentil soup with whole-grain bread, and yogurt with nuts are all good complementary protein pairings you can enjoy.
There are also several ‘foods’ or dishes that give you complementary proteins in what you might already consider to be a single dish. This includes macaroni and cheese, a grilled cheese sandwich, whole-grain cereal with soy milk, and a black bean/brown rice burrito. Making things even better, you can get complementary proteins out of both lasagna and pizza alone, given their complementary ingredients.
What is complementary protein nutrition? You should be able to answer that for yourself now, as you understand the science behind it and also have numerous real-world food options to support it.