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What Are Proteins and How Do They Work in Food?

by Rohail Bukhari on Feb 01, 2023

Take your nutrition knowledge to the next level! Discover what proteins in food do for you, and why they are important for a healthy diet.

What Are Proteins?

Protein is an essential macronutrient [1], meaning they are one of the three main sources of energy your body needs for the function, structure and regulation of the body's tissues and organs (the others are fats and carbohydrates).

They are composed of small building blocks called amino acids [2], which are strung together in long chains and act as building blocks for muscle and tissues in your body, and play an important role in the processes of growth and maintenance.

Proteins also help to regulate many important bodily processes like digestion [3], metabolism [4] and immunity [5].

There are 20 different types of amino acids [6] in the human body that are needed to function properly, and these can be obtained from a variety of different sources, including animal and plant-based foods.

How Do Proteins Benefit The Body?

Proteins in foods are particularly important to your body because they are known as the “building blocks” of life.

The amino acids that make up protein are essential for the proper functioning of the body.

Some of the ways in which protein benefits the body are:

Building and repairing tissues [7]: Protein is necessary for the growth and repair of tissues, including skin, muscle, bones and organs.

Transporting molecules [8]: protein is used for transporting molecules such as oxygen and nutrients, around the body

Providing energy [9]: While carbohydrates and fats are the primary sources of energy within the body, protein can also be used for energy when needed.

Producing hormones and enzymes [10]: Many hormones and enzymes which are responsible for chemical reactions in the body, are made of protein.

Maintaining muscle mass and strength [11]: Protein is important for maintaining muscle mass and strength, particularly in people who are physically active

Supporting the immune system [12]: Protein is necessary for the production of antibodies, which help the body fight off infections and diseases.

How Much Protein Does Your Body Need Everyday?

So, how much protein does your body need every day? The answer depends on a number of factors, including your age, sex, weight, and level of physical activity.

The Recommended Dietary Allowance (RDA) for protein is a general guideline for how much protein you should aim to consume each day. The RDA for protein is [13]:

0.8 grams of protein per kilogram of body weight per day for adults

1.0-1.2 grams of protein per kilogram of body weight per day for athletes and people who are physically active

For example, if you weigh 68 kilograms (150 pounds) and are not physically active, you would need about 55 grams of protein per day (68 x 0.8).

If you are physically active, you would need about 68-82 grams of protein per day (68 x 1.0-1.2).

Protein should be distributed evenly throughout the day [14]—aim for at least 20 grams in each meal.

It is important to note that these recommendations are for the average person and may not be appropriate for everyone.

Some people, such as vegetarians and vegans, may need to be more mindful of getting enough protein, as they may not be getting it from animal-based sources.

Additionally, people with certain medical conditions, such as kidney disease [15], may need to limit their protein intake.

How Is Protein Absorbed?

Protein is absorbed into the body through a process called digestion [16]. Digestion is the breakdown of food into smaller molecules that can be absorbed and used by the body.

Protein digestion begins in the stomach [16], where stomach acid and enzymes called proteases break down the protein into smaller peptides [16]. These peptides are then further broken down into individual amino acids in the small intestine by enzymes called peptidases.

Absorption of the amino acids happens in the small intestine [17] which contains microvilli. These are small, finger-like structures that increase the absorptive surface area of your small intestine. This allows for maximum absorption of amino acids and other nutrients.

Once they've been absorbed into the bloodstream they are transported to the liver [18] for further processing.

How Can I Absorb More Protein?

Here are a few ways in which you can absorb more protein:

Choose high-quality protein sources: Some protein sources, such as lean meats, poultry, fish, and plant-based sources like beans, lentils, and quinoa, are higher in nutrients and lower in unhealthy saturated fats and calories. These types of protein are generally easier for the body to digest and absorb.

Eat a balanced diet: To absorb more protein, it is important to eat a balanced diet that includes a variety of protein-rich foods. This can include animal-based sources such as meat, poultry, fish, eggs, and dairy products, as well as plant-based sources such as beans, lentils, nuts, and seeds.

Spread your protein intake throughout the day [14]: Instead of getting all of your protein at once, try to spread your intake out throughout the day. This can help your body to better absorb and utilise the protein.

Consume with carbohydrates [19]: Carbohydrates can help to shuttle the amino acids into muscle cells, where they can be used for protein synthesis.

Include protein at each meal: Eating protein at each meal can help to ensure that your body is consistently getting a supply of amino acids throughout the day, which can help to increase protein absorption

Consider taking a protein supplement: If you are having trouble getting enough protein from your diet, you may consider taking a protein supplement, such as a protein powder or amino acid supplement. These supplements can be a convenient way to increase your protein intake.

Avoid processed protein sources: Processed protein sources, such as deli meats and processed cheeses, are often high in sodium and unhealthy additives and may not be as nutritious as a whole, unprocessed protein sources. To get the most benefit from protein, it is best to choose whole, unprocessed protein sources

Don't overdo it [15]: While protein is an important macronutrient, it is possible to get too much of it. Consuming too much protein can put a strain on the kidneys and may contribute to dehydration. It is important to consume protein in moderation as part of a well-balanced diet.

What Foundational Habit Will Help Me Absorb More Protein?

To maximise the benefit of protein consumption, it's important to be mindful and intentional in your habits.

One foundational habit that can help you absorb more protein is to eat protein-rich foods regularly as part of a balanced diet.

Eating a variety of protein-rich foods, including both animal- and plant-based sources can help to ensure that you are getting all of the essential amino acids your body needs.

In addition, it is important to eat protein throughout the day, rather than getting all of your protein at once. This can help your body to better absorb and utilise the protein.

Other habits that can help you absorb more protein include:

Choosing high-quality protein sources: Some protein sources, such as lean meats, poultry, fish, and plant-based sources like beans, lentils, and quinoa, are higher in nutrients and may be more easily absorbed by the body.

Eating protein with carbohydrates[19]: Eating protein with carbohydrates can help to increase the absorption of amino acids. This is because the insulin released in response to the carbohydrates can help to shuttle the amino acids into muscle cells, where they can be used for protein synthesis.

Additionally, make sure to drink plenty of water as dehydration can cause a decrease in muscle strength [20] which reduces the efficiency benefits of protein consumption.

By incorporating these habits into your daily routine, you can help your body absorb more protein and ensure that you are meeting your protein needs

Sources of protein In Foods

Animal-based protein sources include meat, poultry, fish, eggs, and dairy products. These sources of protein are considered complete proteins, as they contain all of the essential amino acids in the right ratios [21]. Some examples of animal-based protein sources include:

Beef: A 3-ounce serving of beef contains about 26 grams of protein.

Chicken: A 3-ounce serving of chicken contains about 26 grams of protein.

Fish: A 3-ounce serving of fish contains about 21 grams of protein.

Eggs: One large egg contains about 6 grams of protein.

Dairy products: A cup of milk contains about 8 grams of protein, while a cup of yoghurt contains about 8-12 grams of protein.

Plant-based protein sources include beans, lentils, nuts, seeds, and grains. These sources of protein are often considered incomplete proteins, as they may not contain all of the essential amino acids in the right ratios. However, eating a variety of plant-based protein sources can help to ensure that you are getting all of the essential amino acids your body needs. Some examples of plant-based protein sources include:

Beans: A cup of beans contains about 15 grams of protein.

Lentils: A cup of lentils contains about 18 grams of protein.

Nuts: A handful of nuts (about 1 ounce) contains about 6-7 grams of protein.

Seeds: A tablespoon of seeds (such as pumpkin or sunflower seeds) contains about 4-5 grams of protein.

Grains: A cup of cooked grains (such as quinoa or brown rice) contains about 6-8 grams of protein.

When planning meals that contain a sufficient amount of protein it's important to diversify the foods you consume throughout the day to meet your needs.

Eating a varied diet of both plant-based and animal protein sources can help ensure that your body is getting all the essential amino acids that your body needs.

Protein Deficiency Symptoms And How To Avoid Them

Protein deficiency, also known as protein-energy malnutrition [22], is a condition that occurs when the body does not get enough protein from the diet.

Protein deficiency can have serious consequences for the body, as it can lead to a range of symptoms, including:

Weakness and fatigue: Lack of protein can lead to weakness and fatigue, as the body does not have enough fuel to function properly.

Loss of muscle mass: Protein is important for maintaining muscle mass, and a deficiency can lead to muscle loss and a decline in physical strength.

Slow wound healing: Protein is necessary for the repair and rebuilding of tissues, and a deficiency can lead to slower wound healing.

Edema: Edema, or fluid retention, is a common symptom of protein deficiency, as protein is necessary for maintaining proper fluid balance in the body.

Weak immune system: Protein is important for supporting immune system function, and a deficiency can lead to a weaker immune system and an increased risk of infections and diseases.

To avoid protein deficiency, it is important to consume enough protein-rich foods as part of a balanced diet. Good sources of protein include meat, poultry, fish, eggs, dairy products, beans, lentils, nuts, and seeds.

Vegetarians and vegans may need to be particularly mindful of getting enough protein, as they may not be getting it from animal-based sources.

Conclusion

In conclusion, protein is an essential macronutrient that is important for the structure, function, and regulation of the body's tissues and organs.

It is composed of small building blocks called amino acids, which are strung together in long chains.

There are 20 different amino acids that the human body needs to function properly, and these can be obtained from a variety of sources, including animal and plant-based foods.

Protein is found in many different types of food, including meat, poultry, fish, dairy products, eggs, beans, lentils, nuts, and seeds.

It is important for building and repairing tissues, producing hormones and enzymes, and transporting molecules around the body.

It is also important for maintaining muscle mass and strength, as well as supporting immune system function.

There are different types of proteins, including complete and incomplete proteins.

Complete proteins contain all 20 amino acids in the right ratios, while incomplete proteins are missing one or more of the essential amino acids.

It is important to eat a variety of protein-rich foods to ensure that you are getting all of the essential amino acids your body needs.

Protein is especially important for people who are physically active, as it helps to repair and rebuild muscle tissue after exercise.

It is also important for vegetarians and vegans, who may need to be more mindful of getting enough protein from their diet, as they may not be getting it from animal-based sources.

References:

What Are Proteins and How Do They Work in Food?