If a protein in a food provides us with the essential amino acids, it is called a complete protein. If it does not supply all the essential amino acids, it is called an incomplete protein.

All meat and other animal products are sources of complete proteins. These products include beef, lamb, pork, poultry, fish, shellfish, eggs (the best source of complete proteins), milk, and milk products.

Protein in foods such as grains, fruits, and vegetables are considered incomplete proteins. Plant proteins can be combined to include all of the essential amino acids and form a complete protein. Examples of such combinations are rice and beans, and corn and beans.