Proteins: Complete, Incomplete and Complementary



Proteins are made up of amino acids. Amino acids are the building blocks of protein. There are 20 different amino acids that join together to make all types of protein. Some of these amino acids can’t be made by our bodies, so these are known as essential amino acids. It’s essential that our diet provide these.

Humans can produce 10 of the 20 amino acids. The others must be supplied by food. If we don’t get enough of even 1 of the 10 essential amino acids the body’s proteins degrade. Unlike carbohydrate and fat, the human body does not store excess amino acids for later use—the amino acids must be in the food every day.

The 10 amino acids that we can produce are alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine. Tyrosine is produced from phenylalanine, so if the diet is deficient in phenylalanine, tyrosine will be required as well. The essential amino acids are arginine (required for the young, but not for adults), histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These amino acids are required in the diet.

In the diet, protein sources are labeled according to whether or not they have all the essential amino acids or not. They are called complete or incomplete.

A complete protein source is one that provides all of the essential amino acids.  Animal-based foods such as meat, poultry, fish, milk, eggs, and cheese are complete protein sources.

Plant sources of protein are incomplete, with the exception of soybeans and quinoa. If a vegetarian has a limited diet, they can potentially not be getting their daily protein needs met. They must be careful to eat a wide a variety of protein rich plant foods.

Complementary proteins are two or more incomplete protein sources that together provide adequate amounts of all the essential amino acids.

Lentils for example are low in certain essential amino acids; however, these same essential amino acids are found in greater amounts in barley. Similarly, barley contain lower amounts of other essential amino acids that can be found in larger amounts in lentils. Together, these two foods can provide adequate amounts of all the essential amino acids the body needs. A soup that contains both lentils and barley is an excellent example of a complete protein.

In the past, it was thought that these complementary proteins needed to be eaten at the same meal for your body to use them together. Now studies show that your body can combine complementary proteins that are eaten within the same day.


Maria’s Lentil Barley Soup with Cheese Topping


Lentils are an easy-to-cook legume. They are nutritious, providing you with several nutrients including fiber, folate, iron, potassium, phosphorus, calcium and protein. However, the protein in lentils is incomplete, as it does not contain sufficient amounts of all of the essential amino acids.

However, the barley contains the amino acid the lentils provide making this soup full of complete, complementary protein. Lentils and barley make a complete protein for a vegetarian or vegan. Barley is a highly nutritious whole grain.

To understand more about incomplete, complete and complementary protein go here.

Lentil Barley Soup with Cheese Topping (Vegans of course would omit the cheese)

• 2 tablespoons extra-virgin olive oil
• 1 small onion, finely chopped (about 1 cup)
• 2 cloves garlic minced
• 2 stalk celery, finely chopped (about 1/2 cup)
• 2 medium carrot, finely chopped (about 1/2 cup)
• ¾ tsp dried thyme
• ¼ tsp dried basil
• Coarse salt and freshly ground pepper
• ¾ cup barley
• 1 cup brown lentils, rinsed and drained
• 10 cups chicken or beef broth
• Optional: 1/2 head cauliflower, cored, trimmed, and cut into small florets (about 3 cups)
• 3 ounces Gruyere, Swiss, or Parmesan cheese, shredded (1 cup)
Heat oil in a large pot over medium-high heat. Add onion, celery, carrot, and garlic. Cook stirring occasionally, until vegetables are softened, about 8 minutes. Add barley, thyme and broth; bring to a boil. Set the timer for the length of time the package directions say to cook the barley minus 30 minus. Reduce heat, cover and simmer.

When the timer goes off add the lentils, stir, cover and continue to cook about 30 minutes more until both the barley and lentils are tender. Season with salt and pepper.

Optional: Stir in cauliflower, increase heat to medium-high, and simmer just until cauliflower is crisp-tender, about 5 minutes.

Serve and pass cheese to sprinkle on top.


Easy Microwave Omelet


egg maker omelet

A easy, delicious nutritious omelet can be made with one of my favorite kitchen gadgets the Nordic Microwave Egg Maker. Click on the link and it is on page 3 of the Amazon Recommended Products.

Look how much food you get for only 270 calories! The omelet with the greens and sauteed mushrooms provides 200 calories, 12 grams of protein and 3 grams of fiber. Serve with half a sweet honey crisp apple which adds another 70 calories and 4 grams of fiber.

omelet and apple

To make the microwave omelet, beat two eggs in a small bowl; divide the mixed eggs equally into the two sides. Place in the microwave for one minute and then check doneness. Continue with another 30 seconds until almost set.

If you want to add greens, place some on top and continue another 30 seconds until egg is done to your liking.

I like to use Costco’s Organic Triple Washed Power Greens (Baby kale, chard and spinach). I always buy organic greens since they can be contaminated with pesticides and/or herbicides. For the other produce that is critical to buy organic see my article on the Dirty Dozen).

Power Greens Costco1

Flip one side of the omelet maker onto the other and slide the omelet onto a plate. I like to top with sautéed sliced crimini mushrooms.