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HomeHealth articlesprotein sourceWhat Are the Functions of Proteins in the Body?

Protein - Dietary Requirements, Sources, and Functions

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Proteins are vital nutrients that regulate key metabolic functions of the body. Read this article to know more.

Medically reviewed by

Dr. Achanta Krishna Swaroop

Published At March 31, 2023
Reviewed AtMarch 31, 2023

What Are Proteins?

Proteins are the power horses that steer the essential metabolic functions of the body thus helping in the proper functioning of the body. Proteins are integral constituents of every organ and tissue in our body like muscles, hair, and nails. They are complex macromolecules that are also referred to as building blocks of our body as they play a vital role in regulating the functions of various cells, organs, and tissues of the body.

Proteins are made up of amino acids. To maintain a continuous supply of amino acids to the body, dietary intake of proteins is essential. It is estimated that adults require 0.83 g of protein per kg of their body weight per day. This amount can be derived from any food sources that are rich in protein.

What Are Proteins Made up Of?

Proteins are made up of chemical compounds known as amino acids. These amino acids, when linked and structured in a specific pattern, form a particular protein. Roughly 300 or more amino acids are required to make a protein. The number and sequencing of amino acids are unique to every protein. These amino acids are classified broadly into essential and non-essential amino acids. Essential amino acids need to be supplemented through the diet whereas non-essential amino acids can be produced by the body. They are described in detail below:

Essential Amino Acids:

  • Histidine

  • Isoleucine

  • Leucine

  • Lysine

  • Methionine

  • Phenylalanine

  • Threonine

  • Tryptophan

  • Valine

Non-essential Amino Acids:

  • Alanine

  • Arginine

  • Asparagine

  • Aspartate

  • Cysteine

  • Glutamate

  • Glutamine

  • Glycine

  • Proline

  • Serine

  • Taurine

  • Tyrosine

What Are the Dietary Requirements for Protein?

According to the European Food Safety Authority (EFSA), an average adult requires 0.83 g of protein per kg of body weight per day. The requirements vary depending on the developmental stage, gender, physical activity, and age. The protein requirements are considerably higher in children, pregnant women, and lactating mothers. Athletes, sports players, and bodybuilders also require a higher quantity of protein.

Dietary Requirements for Protein

What Are the Dietary Sources of Protein?

Proteins can be obtained from either plant or animal sources. Nuts, milk, egg, lentils, soy, seafood, beans, and peas are rich sources of proteins. Animal-based sources are a wholesome source of complete proteins whereas plant sources tend to lack a few.

Dietary Sources of Protein

What Are the Functions of Protein in Our Body?

Proteins are a crucial element of all vital body tissues and organs. They help build muscle and other body tissues and thus are responsible to maintain the structure of the body. Proteins have various crucial functions in the body as they are key in producing hormones, enzymes, and other essential biological substances that are important to perform the metabolic activities. The functions of proteins are described in detail below:

1. To Function as Enzymes:

Enzymes are biochemical substances that are responsible for certain chemical reactions in the body. Various chemical reactions are happening in every cell of the body. Few proteins act as enzymes that function as the primary catalyst for these reactions. Every enzyme is specific and individualized for a particular chemical reaction. Breaking down food, converting the nutrients in them to energy, and storing them for future use all are enzymatic reactions that are mediated by proteins.

2. For Hormone Synthesis:

Hormones are chemical messengers in the body that carry out various important functions. Proteins are the key element in hormone synthesis. A few examples of hormones made from proteins are insulin, melatonin, thyroid hormone, and glucagon.

3. Maintain Fluid and Electrolyte Balance:

Proteins are essential to maintain the fluid-electrolyte balance in the body. Too much and too little water in the body can be consequential. Constant high-concentration circulation of protein in the blood helps attract water thereby maintaining the water concentration.

4. Maintaining Acid-Base Balance:

Proteins are important to maintain the pH in the blood. The pH of the blood should be maintained between 7.35 and 7.45 which is slightly alkaline. Too acidic or too alkaline blood pH could result in systemic illness. Proteins act as buffers and thus can maintain the pH of the blood.

5. Nutrient Transport:

Certain specialized proteins also known as transport proteins help to move nutrients and other molecules in and out of the cell.

6. Immune System:

The body’s immune system is the primary defense mechanism against foreign substances. The immune system produces antibodies which are nothing but specialized proteins that can attack the foreign body or the pathogen and prevent any illness.

7. Wound healing and tissue regeneration:

Proteins are essential in all aspects of wound healing from generating a blood clot to arrest bleeding to the regeneration of tissue. Proteins are an integral part of the cell cycle where cell repair and cell death happen periodically. The amino acids present in the cell are recycled into proteins.

8. As an Energy Source:

Though proteins contribute little energy, they are a vital source of energy in individuals whose diet lacks carbohydrates and fats.


Proteins are vital components required for sustaining life. It plays a crucial role in various metabolic functions of the body that are required for growth and development. Various food sources act as a reservoir of protein. Diet poor in protein could result in deficiency leading to various systemic illnesses. Thus choosing protein-rich food will help support a healthy and sustainable diet and also help meet the daily protein requirement.

Frequently Asked Questions


How Much Protein Does an Egg Contain?

Eggs are regarded as the complete source of protein. Eggs are nutrient-rich food, amounting to a high protein quality per egg. The amount of protein content varies depending on the size of the egg. However, each contains about six to seven grams of protein. So, a large egg could make six grams of protein, while an extra large could make about seven grams.


How Much Protein Is Recommended for Daily Intake?

Per the dietary reference intake suggestion for macronutrients, sedentary adults must intake 0.36 grams of protein for one pound of body weight. So, the average weighted man should take about 56 grams of protein, and an average sedentary woman should take about 46 grams per day. The person who takes 2000 calories per day must consider consuming 200 to 700 calories from protein sources.


What Is the Protein Content Of Bananas?

Like other fruits, bananas are not a good source of protein or fat. They just contain carbohydrates. Bananas constitute low levels of proteins. It has under 1.5 grams of protein per medium-sized banana. One serving can provide about 0 grams of fat, 1 gram of protein, 28 grams of carbohydrates, 110 calories, 15 grams of sugar, 460 mg of potassium, and 3 grams of fiber. So, bananas cannot be considered protein sources for adding to the diet.


What Is the Cause of Protein in Urine?

The common causes for a temporary increase in protein in urine can be the following.

- Dehydration.

- Diet changes.

- Pregnancy.

- Stress.

- Strenuous exercises.

- Other conditions.

A small quantity of protein in urine is considered normal, but a large portion of protein can indicate any underlying kidney disease.


What Is the Protein Requirement for Muscle Building?

People doing weightlifting and athletics prefer adding muscle mass as they use the muscles more than normal people. The recommended daily amount of protein is about 1.2 to 2.0 g/kg body weight for endurance training and athletics. The high-protein foods include chicken breast, cod, salmon, fish, nuts, seeds, eggs, and whey protein.


What Is the Protein Content of Peanut Butter?

As we all can see, peanut butter is a rich source of heart-healthy fats and protein. Peanut butter is a famous food item often praised for its good protein content. This can be a great choice for vegetarians looking for more protein in their diet. Two tablespoon servings of peanut butter constitute up to eight grams of protein while two to three grams of fiber


What Are the Consequences of Too Much Protein Consumption?

Excess degrees of protein consumed are generally stored as fat in the system. While the surplus of amino acids from them is excreted. This could often result in weight gain with time, particularly for individuals who intake more calories as trying to raise their protein intake. The symptoms associated with excess protein intake include:

- Nausea.

- Headache.

- Irritability.

- Diarrhea.

- Dehydration

- Indigestion.

- Intestinal discomfort.


What Amount of Protein Is Required for Losing Weight?

The recommended protein intake is 0.36 grams of protein per pound of body weight. If one is aiming for weight loss, consider taking a daily protein amount between 0.73 and 1 gram per pound. Conversely, athletes and strenuous exercisers must consume 1 to 1.5 grams of protein per pound if working over weight loss. One can calculate the amount of protein according to body weight when aiming for weight loss.


What Is the Calorie Content in a Gram of Protein?

Generally, carbohydrates provide four calories per gram, and fat provides nine calories per gram. Protein equates to four calories per gram. Moreover, the U.S. Department of Agriculture (USDA) validates that protein has four calories per gram. The major food sources of protein include certain animal sources such as meat, fish, eggs, and dairy products.


What Foods Items are Fast-Digesting Proteins?

The food sources rich in animal protein are pork, lamb, beef, fish, poultry, milk, and milk products. Everyone has second thoughts about what kind of meat can be the most easily digested in the case of animal protein sources. Lean animal products, including fish, chicken breast, and egg protein, are fast-digesting food sources. Whey protein isolate might be a good choice in case one does not prefer dairy since whey protein is lactose-free.


Name Non-perishable Foods With Protein.

Canned tuna can be the most popular and good source of protein. Other Cannes meats like turkey, chicken, and salmon are considered a great source of protein. The other non-perishable food sources that are enriched with nutrients, including protein, are:

- Pulses.

- Wheat berries.

- Hemp seeds.

- Cheese crisps.

- Pistachios.

- Sardines.

- Jerky.


What Affects Protein Structure?

The factors that affect protein structure and the protein folding process include the following.

- Conformational and compositional stability.

- Environmental factors, including temperature and pH.

- Primary and secondary structure.

- Solvation.

- Salt bridges.

- Hydrogen binding capacity.

- Ligand binding.

- Cofactor binding.

- Van Der Waal forced.


Can Dehydration Cause High Protein in Urine?

Dehydration can cause a temporary increase in urine protein concentration. So, dehydration might cause Proteinuria (protein in urine). When the body loses the liquids and does not replace them, it can be difficult for them to deliver essential and required nutrients to the kidneys. This results in problems with the re-absorption of proteins by the kidneys, causing protein excretion in urine.


What Helps Prevent Acne While Taking Whey Protein?

Here are certain ways to prevent acne breakouts caused by whey protein intake.

- Shower right after a workout and strenuous exercise exercises.

- Avoid wearing tight clothes during workouts.

- Consider reducing the intake of whey protein.

- One can use a medicated acne ointment containing Benzoyl peroxide or Salicylic acid.

Source Article IclonSourcesSource Article Arrow
Dr. Achanta Krishna Swaroop
Dr. Achanta Krishna Swaroop



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