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Incomplete vs. Complete Proteins

Nov 24, 2009

Protein is an essential part of a diet to maintain balanced nutrition. It performs many important functions, such as building lean body tissue and creating digestive enzymes. Not all protein is created equal, however. There are complete and incomplete proteins, which are found in different food sources. This article will outline the difference between the two, and how to incorporate them into your diet for full protein requirements of the body.

Almost all whole foods contain protein. Some contain more amino acids than others, and some contain all the amico acids necessary for optimal dietary needs. Proportions of these amino acids may vary from one food to another. Meals that combine a variety of protein foods can provide all the essential amino acids that may be lacking from one particular source. Vegetable protein sources are often lacking in one or more essential amino acids, as opposed to animal proteins which are generally considered complete proteins.

Complete Proteins

A complete protein contains an adequate amount of all of the essential amino acids that should be incorporated into a diet. Some protein contains all the amino acids needed to build new proteins, which generally come from animal and fish products. A complete protein must not lack even one essential amino acid in order to be considered complete.

Sources of Complete Proteins

The following foods are examples of complete proteins, which need not be combined with any other food to provide adequate protein:

  • Meat
  • Fish
  • Poultry
  • Cheese
  • Eggs
  • Yogurt
  • Milk

Incomplete Proteins

An incomplete protein is any protein that lacks one or more essential amino acids in correct proportions. These can also be referred to as partial proteins. Even if the protein contains all the essential amino acids, they must be in equal proportions in order to be considered complete. If not, the protein is considered incomplete.

Sources of Incomplete Proteins

The following foods are examples of incomplete proteins:

  • Grains
  • Nuts
  • Beans
  • Seeds
  • Peas
  • Corn

Combining Incomplete Proteins to Create Complete Proteins

By combining foods from two or more incomplete proteins, a complete protein can be created. The amino acids that may be missing from one type of food can be compensated by adding a protein that contains that missing amino acid. When eaten in combination at the same meal, you are providing your body with all the essential amino acids it requires. These are considered complementary proteins when they are combined to compensate for each other's lack of amino acids.

Samples of Complementary Proteins

Examples of combined complementary proteins to create a complete protein in one meal include:

  • Grains with Legumes - sample meal: lentils and rice with yellow peppers.
  • Nuts with Legumes -  sample meal: black bean and peanut salad.
  • Grains with Dairy - sample meal: white cheddar and whole wheat pasta.
  • Dairy with Seeds - sample meal: yogurt mixed with sesame and flax seeds.
  • Legumes with Seeds - sample meal: spinach salad with sesame seed and almond salad dressing.

By learning what foods complement each other, it is possible to create a perfectly balanced meal with the proper proportions of proteins. This will ensure that your body is getting all the essential amino acids it requires for optimal bodily functions.

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