Protein is made up of building blocks called amino acids. Your body makes some amino acids. These are called nonessential amino acids. Other amino acids must come from the foods you eat. These are called essential amino acids. A protein with all the essential amino acids is considered a higher quality or complete protein. Animal sources of protein such as meat, milk and eggs are complete.
The source can be important. A protein lacking one of more essential amino acids is considered incomplete. Plant sources of protein don’t contain all the essential amino acids your body needs and are considered incomplete.
Why do we need protein?
- Growth (especially children, teens, pregnant women)
- Tissue repair
- To make essential hormones and enzymes in the body
- For energy if other energy sources, like carbohydrates, are not available
How much do we need?
You only need about 15-20% of your daily calories from protein and most American’s get enough. The Recommended Dietary Allowance (RDA) for most healthy adults is approximately 50-60 grams per day. The RDA for growing children, adolescents, and pregnant women is higher.
Common sources in the diet. You can see how easy it is to get the recommended amount.
|Food source||Grams of protein|
|4 ounces grilled chicken breast||34|
|4 ounces broiled lean steak||27|
|1/2 cup cottage cheese||14|
|1 cup cooked kidney beans||13|
|2 tablespoons peanut butter||8|
|8 ounces milk (1% fat)||7|
|4 ounces tofu||7|
|4 ounces cooked pasta noodles||6|
|2 slices whole wheat bread||5|
How can you be sure you are getting enough complete protein?
You can still get all of your essential amino acids from vegetable or plant sources if you eat a variety of plant-based foods.
Do athletes need more protein?
Extra protein in the diet isn’t usually necessary. Contrary to popular belief, eating more won’t give you more muscle. The only way to make your muscles bigger is to exercise the muscles. If you eat too much protein, the extra amount that is not needed for growth and repair is just extra calories. Extra calories, regardless of the source get stored as body fat.
Words to know
Essential amino acids. Amino acids that our bodies cannot make and we must get from food sources
Nonessential amino acids. Amino acids that our bodies are able to make
Complete protein. Protein source containing all of the essential amino acids
Incomplete protein. Protein source missing one or more essential amino acid