Assignment: due today

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.

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.

• 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.

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.

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.

ChooseMyPlate.gov Daily Food Plan lets you enter your age, sex, weight, height and physical activity level to get a personalized plan just for you.

Is there any harm in getting more protein than I need? Most people eat more protein than they need without harmful effects. However, protein contributes to calorie intake, so if you eat more protein than you need, your overall calorie intake could be greater than your calorie needs and contribute to weight gain. Besides that, animal sources of protein can be sources of saturated fat which has been linked to elevated low-density lipoprotein (LDL) cholesterol, a risk factor for heart disease. In addition, for people with certain kidney diseases, a lower-protein diet may be recommended to help prevent an impairment in kidney function.