images of various protein-rich foods such as fish, eggs, chicken, red meat and beans What do you think about when you hear the word protein? Maybe it's an ad for some protein shake that promises massive muscles? Or is it the last high-protein diet craze you read about? With all this talk about protein, you might think Americans were at risk for not eating enough. In fact, most of us eat more protein than we need. Protein is in many foods that we eat on a regular basis.

This section will help you learn more about protein. You'll find information about what foods have protein and what happens when we eat more protein than we need.

What is Protein?

Proteins are part of every cell, tissue, and organ in our bodies. These body proteins are constantly being broken down and replaced. The protein in the foods we eat is digested into amino acids that are later used to replace these proteins in our bodies.

Protein is found in the following foods:

	meats, poultry, and fish
	legumes (dry beans and peas)
	tofu
	eggs
	nuts and seeds
	milk and milk products
	grains, some vegetables, and some fruits (provide only small amounts of protein relative to other sources)

As we mentioned, most adults in the United States get more than enough protein to meet their needs. It's rare for someone who is healthy and eating a varied diet to not get enough protein.

What are the types of protein?

Proteins are made up of amino acids. Think of amino acids as the building blocks. 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.

In the diet, protein sources are labeled according to how many of the essential amino acids they provide:

A complete protein source is one that provides all of the essential amino acids. You may also hear these sources called high quality proteins. Animal-based foods; for example, meat, poultry, fish, milk, eggs, and cheese are considered complete protein sources.

photo of various foods

An incomplete protein source is one that is low in one or more of the essential amino acids. Complementary proteins are two or more incomplete protein sources that together provide adequate amounts of all the essential amino acids.

photo of various foods

For example, rice contains low amounts of certain essential amino acids; however, these same essential amino acids are found in greater amounts in dry beans. Similarly, dry beans contain lower amounts of other essential amino acids that can be found in larger amounts in rice. Together, these two foods can provide adequate amounts of all the essential amino acids the body needs.

Is it true that complementary proteins must be eaten together to count as a complete protein source?

How much protein do I need?

Maybe you've wondered how much protein you need each day. In general, it's recommended that 10–35% of your daily calories come from protein. Below are the Recommended Dietary Allowances (RDA) for different age groups.²

Here are examples of amounts of protein in food:

	1 cup of milk has 8 grams of protein
	A 3-ounce piece of meat has about 21 grams of protein
	1 cup of dry beans has about 16 grams of protein
	An 8-ounce container of yogurt has about 11 grams of protein

Added together, just these four sources would meet the protein needs of an adult male (56 grams). This doesn't count all the other foods that add smaller amounts of protein to his diet.

Rather than just focusing on your protein needs, choose an overall healthy eating plan that provides the protein you need as well as other nutrients.