What is the role of protein? 9 important functions of protein for the body

by Johnny Jacks
The term “Protein” originates from the Greek word meaning “main” or “first place.” Proteins play a critical role as essential nutrients in the body. Learn about the 9 crucial functions of proteins in the article below.

What are proteins as nutrients?

Before delving into their role, it’s important to understand nutritional proteins. These complex compounds, known as amino acids, form the fundamental building blocks. They link to create long chains vital for the cellular functions.

There exist 20 types of amino acids that facilitate various chemical reactions in the body. Their specific arrangement dictates the function and shape of the proteins.

Since the body cannot produce these crucial proteins, a protein-rich diet is necessary for cell and tissue growth and maintenance. Normally, the body contains 10% to 20% nutritional proteins relative to body weight. The European Food Safety Authority (EFSA) recommends a minimum protein intake of 0.83g per kilogram of body weight per day for adults.

9 Important Functions of Protein in the Body

What role does protein play? Various types of proteins serve distinct functions in the body. Here are the 9 most critical ‘missions’ of proteins.

Growth and maintenance of tissues

The body requires a specific amount of protein for tissue growth and maintenance. Proteins continuously undergo a ‘circulation’ process. Normally, the body breaks down protein for tissue repair and construction. However, during illness, post-surgery, pregnancy, intense physical activity, and more, the body might require more protein than usual.

Protein serves as a catalyst for chemical reactions in the body

Enzymes, a type of protein, facilitate thousands of biochemical reactions within and outside cells. Enzymes possess a distinctive structure enabling them to bind with various molecules within the cell, known as the substrate. Proteins act as vital catalysts for most metabolic reactions.

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The bodily functions in which enzymes contribute include digestion, energy production, blood clotting, and muscle contraction. The absence or malfunctioning of an enzyme can jeopardize the body’s well-being.

Transmission of information

Proteins also carry a critical responsibility as neurotransmitters, ensuring the smooth functioning of the nervous system. Proteins act as ‘messengers,’ transmitting signals to cells and governing the central nervous system.

Some examples of protein’s roles as messengers include:

  • Insulin: Signaling the absorption of glucose or sugar into cells.
  • Glucagon: Signaling the breakdown of stored glucose in the liver.
  • HGH (growth hormone): Stimulating the growth of tissues, including bones.
  • ADH (antidiuretic hormone): Signaling the reabsorption of water by the kidneys.
  • ACTH (adrenal cortex hormone): Stimulating the release of cortisol, a crucial factor in metabolism.

Protein Aids in Shaping Tissue and Cell Structure

Certain proteins in the form of fibers possess the ability to confer a specific level of elasticity, rigidity, and strength to cells and tissues. These proteins include:

  • Keratin: Structural protein primarily found in the skin, hair, and nails.
  • Collagen: The most abundant protein in the body, forming the framework of bones, tendons, skin, and ligaments.
  • Elastin: A supple protein with high elasticity that allows numerous tissues to regain their original shape after stretching (e.g., uterus, arteries, lungs), aiding in the formation of the connective framework of various structures in your body.

Protein Helps Maintain the Body’s Optimal pH Level

When discussing the role of protein, one cannot overlook its function in regulating the body’s pH. Protein acts as a buffer that helps control the concentration of acids and bases in the blood and various bodily fluids, facilitating the transportation of ions in the circulatory system. These proteins transport water present in cells and blood vessels, ensuring that bodily fluids maintain a normal pH range. A reduction in the amount of protein in the blood results in edema due to decreased osmotic pressure in the blood vessels.

Hemoglobin serves as an example of this protein function, aiding in the stabilization of blood pH when bound to a small amount of acid.

Even slight changes in the body’s pH can be detrimental, even life-threatening. Ensure that your body can regulate its pH levels by consuming adequate protein.

Fluid Balance

In addition to pH regulation, protein also plays a pivotal role in regulating bodily processes that help maintain fluid balance. For instance, albumin and globulin, present in the blood, assist in sustaining the body’s fluid equilibrium by attracting and retaining water.

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Insufficient protein intake can lead to a drop in albumin and globulin levels. Consequently, these proteins lose their capacity to retain blood in the blood vessels, causing fluids to accumulate in the spaces between cells. This can result in swelling or edema, commonly observed in the abdominal region. Severe malnutrition, known as kwashiorkor, frequently occurs in impoverished regions.

Protein Enhances Immune System Health

Protein is also recognized for its role in the formation of immunoglobulins, critical antibodies that safeguard our bodies from harmful invaders such as bacteria and viruses. Without an adequate supply of protein, bacteria and viruses can proliferate unchecked, leading to various diseases.

What Role Does Protein Play? Protein serves the function of transporting and storing nutrients.

Proteins are accountable for conveying substances throughout your bloodstream – both within cells and in and out of cells, facilitating the smooth circulation of blood and nourishment of cells. The nutrients transported by these proteins include vitamins and minerals, blood sugar, cholesterol, and oxygen.

Moreover, proteins also undertake the role of storage. Ferritin, for instance, serves as a storage protein that aids the body in storing iron. Another form of storage protein is casein – the primary protein in milk that fosters the growth of infants.

Providing Energy for the Body

Constituting 10-15% of the energy in the diet, protein plays a crucial part in supplying energy for the body. Protein is converted into 4 calories per gram, which is equivalent to the energy content provided by carbohydrates. Additionally, protein aids in stimulating appetite and plays a vital role in many healthy diets.

How Does Excessive or Inadequate Protein Intake Affect the Body?

Although the significance of protein is undeniable, nutritionists caution that both excessive and insufficient protein consumption can lead to adverse health consequences.

Consequences of Excessive Protein Intake

Some potential outcomes of excessive protein consumption include:

  • Weight gain: Without a consistent exercise regimen, surplus protein can be stored as excess fat, leading to uncontrolled weight gain.
  • Risk of Kidney and Liver Diseases: Excess protein intake places continuous strain on the kidneys and liver, potentially impairing their function. Moreover, it increases the risk of gout and certain types of cancer. Uncontrolled protein consumption can severely impact the brain, liver, and nervous system.
  • Constipation: Imbalanced consumption of protein without a corresponding intake of starches, vegetables, and fruits can lead to constipation.
  • Dehydration: Excess protein in the body can lead to increased water loss, as protein requires water for proper functioning.
  • Osteoporosis: Overconsumption of protein prompts the release of acid, causing the body to tap into calcium phosphate stored in the bones, resulting in osteoporosis.
  • Limiting the Absorption of Other Nutrients: Overemphasis on protein intake often leads to an inadequate intake of other essential nutrients, particularly fiber. It is crucial to maintain a balanced and nutrient-rich diet.
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Consequences of Inadequate Protein Intake

Insufficient protein intake can result in:

  • Poor Nutrient Absorption: Inadequate protein consumption disrupts the absorption and transportation of various essential nutrients.
  • Edema: Low levels of protein in the blood can decrease osmotic pressure in blood vessels, leading to edema.
  • Physical Weakness: A diet lacking in protein can cause weakness, skin elasticity loss, hair loss, muscle and bone underdevelopment, menstrual disorders, and hormonal imbalances.

Foods Rich in Protein to Include in a Balanced Diet

Once you grasp the significance of protein in the body, you might be curious about the sources of this essential nutrient. Protein is present in various everyday foods that you likely consume regularly, falling into two primary categories:

  • Animal protein: Protein is abundant in foods such as beef, chicken, fish, eggs, and milk. These animal-based products contain all the necessary amino acids, often referred to as ‘complete proteins.’
  • Plant proteins: These are considered the healthiest sources of protein, yet they are often categorized as ‘incomplete proteins’ due to their deficiency in at least one essential amino acid. Vegetarians can compensate for this by incorporating a diverse range of plant-based protein sources.
  • While animal proteins are generally of higher quality, encompassing most essential amino acids, a healthy and varied diet should include both animal and plant-based protein sources to fully harness the extensive benefits of protein.
  • Recommended Protein Intake: For specific target groups, you can consult the protein intake recommendations provided by the Institute of Medicine (IOM).

Age and gender

Recommended daily protein intake (g)


0-6 months


6-12 months


1-3 years old


4-8 years old



9-13 years old


14-18 years old


Over 19 years old



9-13 years old


Over 14 years old


Pregnant/lactating women


Hence, the preceding article has provided you with a comprehensive understanding of the significance of protein. We trust that this knowledge will assist you in establishing a wholesome and efficient diet, enabling you to meet your daily nutritional requirements. Wishing you continued good health, and please do not hesitate to share the article if you find it beneficial!

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