What Is Protein?

What is protein?

Protein is an essential nutrient found throughout the body. It is made from smaller units called amino acids and is needed to build, maintain, and repair body tissues.

After you eat protein-containing foods, digestion breaks the protein down into amino acids. Your body can then use those amino acids to make the proteins it needs.

What does protein do?

Protein does much more than support muscle.

Your body uses protein to help:

• build and maintain tissues
• repair cells
• support growth and development
• make enzymes and many hormones
• support normal immune function
• carry out many everyday processes throughout the body

Protein can also provide energy. One gram of protein provides about 4 calories.

What are amino acids?

Amino acids are the building blocks of proteins.

The human body uses 20 different amino acids to build proteins. Nine are considered essential because the body cannot make enough of them and they therefore need to come from food.

The nine essential amino acids are:

• histidine
• isoleucine
• leucine
• lysine
• methionine
• phenylalanine
• threonine
• tryptophan
• valine

You do not need to eat every essential amino acid at every meal. What matters more is getting an adequate balance across your overall diet during the day.

Which foods contain protein?

Protein is found in both animal and plant foods.

Common animal sources include:

• meat and poultry
• fish and seafood
• eggs
• milk and other dairy foods

Plant sources include:

• beans
• lentils
• peas
• soy foods
• nuts
• seeds
• some grains

You can explore examples in Eat Ate Here, including chicken breast, salmon, whole egg, peanuts, and fresh milk.

Do plant proteins need to be combined at every meal?

No.

Different plant foods provide different amounts of amino acids, but you generally do not need to deliberately pair specific proteins at every meal.

A varied diet across the day can provide the amino acids your body needs.

For example, foods such as beans, lentils, soy, nuts, seeds, and grains can all contribute protein as part of an overall varied diet.

How much protein do you need?

There is no single protein amount that is right for everyone.

Protein needs can vary with factors such as:

• age
• body size
• sex
• activity level
• growth
• pregnancy
• health status
• overall energy needs

This is why a daily protein target should be understood as a reference rather than a universal amount that applies equally to every person.

Eat Ate Here can help you see how much protein your logged foods contribute to your daily nutrition, but it does not replace individualized advice from a qualified healthcare professional.

Is more protein always better?

Not necessarily.

The amount of protein matters, but the food providing that protein also matters.

Two foods can contain similar amounts of protein while having very different amounts of:

• total fat
• saturated fat
• sodium
• fiber
• vitamins
• minerals
• calories

Looking at the complete nutrition profile gives more context than judging a food only by its protein content.

How does protein fit into overall nutrition?

Protein is one important part of nutrition, but it works alongside carbohydrates, fats, fiber, water, vitamins, and minerals.

Instead of asking only:

How much protein does this food contain?

It can also be useful to ask:

What else does this food contribute to my overall nutrition?

That broader view is why Eat Ate Here tracks protein together with other important parts of daily nutrition.

Practical takeaway

Protein is an essential nutrient made from amino acids and used throughout the body.

Both animal and plant foods can provide protein. Rather than focusing only on getting as much protein as possible, consider your overall needs, the variety of foods you eat, and the rest of the nutrition those foods provide.