Protein - the Building Block of Life
What is Protein?
Protein is one of the important macronutrients. Protein originated from the Greek word “proteios”, meaning prime or primary.
This term is very appropriate in nutrition because protein is the most fundamental component of tissues in animals and humans.
It is essential for the maintenance and building of tissues and muscles of our body. Proteins are made of small compounds called amino acids.
They are fundamental components of all living cells and include many substances, such as enzymes, hormones and antibodies that are necessary for the proper functioning of an organism.
They are essential for the growth and repair of tissue and can be obtained from foods such as meat, fish, eggs, milk, and legumes.
Why is Protein a Macronutrient?
The food we eat can be classified mainly into five major kinds of nutrients namely vitamins, minerals, carbohydrates, proteins, and fats. Additionally, food also contains water and dietary fibres/roughage and water which are also required by our bodies.
Of all these nutrients, carbohydrates, proteins, and fats are considered as macronutrients because the body needs them in large amounts.
How much protein should I take daily to maintain good health?
Daily protein intake plays a key role in our daily health maintenance. It is recommended that 15 to 20% of the diet come from protein. Proteins contain 4 calories per gram.
Can I get complete protein by being vegetarian?
Adequate consumption of high-quality protein is essential for optimal growth, development, and health in humans.
An appropriate mixture of animal- and plant-based foods is a practical way to ensure balanced provision of dietary amino acids .
The body needs 22 amino acids in order to grow and develop properly. The body can produce most of these amino acids itself.
However, there are 9 amino acids that our body cannot produce and must be received through the food we eat and are known as essential amino acids.
Foods that contain all 9 essential amino acids are complete proteins. All animal products are complete proteins meat milk poultry cheese fish eggs.
Not all protein foods have all 9 essential amino acids – these foods are called incomplete proteins (plants may be rich in protein – but are incomplete). It is possible to combine two incomplete proteins to make a complete protein.
As a vegetarian, you can combine two plant foods together to make a complete protein. Examples,
a. Wheat bread and peanut butter
b. Legumes and seeds
c. Legumes and grains as in khichdi
d. Rice and dal as in Idli, or
What happens to excess proteins in the body?
You should get a minimum of 10% of your daily calories from protein.
The current international Recommended Dietary Allowance (RDA) for protein is 0.8 g per kg of body weight (bw), regardless of age . In the UK, the Reference Nutrient Intake (RNI) is 0.75 g/kg bw. In India it is 0.83g/kg bw.
Excess protein cannot be stored in the body. The body will only use as much protein as it needs. The excess is converted into glucose and burned as energy or stored as fat. The body needs a daily supply of protein. Small amounts of protein at each meal are better than one large serving.
What are the Sources of protein?
You should try to get the daily required protein from a variety of sources throughout the day.
Are there any negative effects of having excess protein in the body?
Excess protein causes:
Dehydration, because more water is needed to flush protein out of the system.
Strain on liver and kidneys.
A need for more calcium – which results in a calcium deficiency.
A small amount of extra protein is only needed by 1. Pregnant mothers. 2. Adolescents. 3. Seriously ill/injured. 4. Athletes on a strenuous training program.
What are the effects of protein deficiency?
Protein deficiency signs
In an era of high-protein, low-carbohydrate diets, one’d think that a protein deficiency is unheard of, but many people skimp on this mighty macronutrient, especially those who are onto intermittent fasting or cutting calories.
Besides thinning hair to sugar cravings, there might be other subtle or obvious signs of a protein deficiency. Some common signs of protein deficiency include:
Protein is necessary to maintain an adequate balance of fluid in our body. One of the most common signs that you're not getting enough protein is swelling (also called oedema), especially in your abdomen, legs, feet, and hands.
Our brain uses chemicals called neurotransmitters to relay information between cells. Many of these neurotransmitters are made of amino acids, which are the building blocks of protein. So, a lack of protein in your diet could mean your body can't make enough of those neurotransmitters, and that would change how your brain works. Protein can boost one’s mood by providing the amino acids that are essential to the production of feel-good neurotransmitters- serotonin and dopamine. With low levels of dopamine and serotonin, one may feel depressed or overly aggressive.
Hair, Nail, and Skin Problems
These are made up of proteins like elastin, collagen, and keratin. When our body is unable to produce them, one could have brittle or thinning hair, dry and flaky skin, and deep ridges on fingernails. Although diet isn't the only possible cause, but it's something to consider. After a few months of not eating enough protein, you may also experience some hair loss, according to the in part because the body shuts down hair growth to preserve its protein stores.
Weakness and Fatigue
You probably won’t feel fatigued right away, but over time, if you aren’t eating enough protein, you may feel more tired or sluggish than usual.
Research shows that just a week of not eating enough protein can affect the muscles responsible for your posture and movement, especially if you are 55years or older.
And over time, a lack of protein can make you lose muscle mass, which in turn cuts your strength, makes it harder to keep your balance, and slows your metabolism.
Moreover, protein is a component of haemoglobin, which is present in our red blood cells and transports oxygen throughout the body.
Thus, protein deficiency can also lead to anaemia, when your cells don't get enough oxygen, which makes you tired.
Protein is one of three sources of calories, along with carbohydrate and fat. It gives a feeling of satiety or fullness. If you always feel like eating or not do not feel satiated a lot times, even though you have regular meals, you might need more protein in your daily diet.
Slow-Healing of wounds
People who are on deficient protein diets often find their cuts and injuries take longer to get better. The same seems to be true of sprains and other exercise-related mishaps. It could be another effect of the body not making enough collagen-which is a protein. It's found in connective tissues as well as one’s skin. Proteins are required for blood clotting too.
Amino acids in our blood help our immune system make antibodies that activate white blood cells to fight off viruses, bacteria, and toxins. We need protein to digest and absorb other nutrients that keep us healthy.
There's also evidence that protein can change the levels of disease-fighting "good" gut bacteria.
If our diet is deficient in protein, we could have a compromised immune system and perhaps be ill more often than other people.
1. Food and Nutrition Board (FNB) of the Institute of Medicine . Dietary Reference Intakes for Energy, Carbohydrate, Fibre, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids (Macronutrients) The National Academies Press; Washington, DC, USA: 2005.
2. World Health Organisation (WHO) Dietary Reference Intakes for Energy, Carbohydrate, Fibre, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids (Macronutrients) World Health Organisation (WHO); Geneva, Switzerland: 2007. (WHO Technical Report Series 935). G. Wu Amino Acids: Biochemistry and Nutrition , CRC Press, Boca Raton, Florida, 2013 .
3. ICMR, 2020. Recommended dietary allowances and estimated average requirements nutrient requirements for Indians – 2020, ICMR-National Institute of Nutrition Hyderabad, India
4. J. Reeds , D. G. Burrin , B. Stoll and J. B. van Goudoever , Nestle Nutr. Workshop Ser., Clin. Perform. Programme, 2000, 3 , 25 —40 .
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