Definition
Proteins, along with fats and carbohydrates, are essential macronutrients required by the body to survive and grow. Your body requires relatively large amounts of it.
They are present in all parts of our body such as muscle, bone, skin, hair, and almost every other body part or tissue. They are molecules present in body cells and are essential to all living organisms.
Proteins are large, complex molecules required for the structure, function, and regulation of these body tissues.
The different types of proteins are made up of 20 amino acids attached to each other by long chains. Different types of amino acids combine to form a protein.
The sequence of the amino acids determines the unique structure of the proteins and their specific function. The typical protein is particularly designed to help it perform its specific function in the cell.
They are one of the building blocks of the body tissue and act as a fuel source to provide energy to the body, as much as carbohydrates – 4 kcal per gram. However, in comparison, lipids provide 9 kcal per gram.
The following posts tell you about your daily protein needs and the foods that contain a good amount of it.
Additionally, the Healthy Eating Plate tells you how to balance the proteins in your diet.
Types of proteins and their food sources
There are two types of proteins classified on the basis of their sources:
- animal-based and
- plant-based
Sources of animal proteins include:
- Whey (dairy products such as milk, yogurt, and cheese)
- Casein (milk, yogurt, cheese, and other dairy products)
- Egg
- Beef
- Poultry from sources such as chickens and turkeys
- Fish
Sources of plant-based proteins include
- Tofu, Tempeh and Edamame
- Lentils
- Chickpeas
- Kidney beans
- Green peas
- Mixed seeds
- Chia seeds
The main difference between animal and plant proteins is their amino acid content. Most animal-based proteins are complete proteins providing all the 9 essential amino acids (EAAs).
On the other hand, most plant-based proteins are incomplete, missing at least one essential amino acid. The way around this is to have multiple plant proteins together to create the complete effect.
Whey proteins, which are of animal origin derived from milk and its products have a positive effect on skeletal muscle and tissue repair and are, therefore, recommended for athletes and older people. Besides being a complete protein, whey proteins contain abundant quantities of Branched Amino Acids (BCAAs). These are a division of EAAs and support muscle growth.
Functions (Benefits) of proteins
The functions of proteins are diverse. For the good health of your body, they are vital. They are essential for the growth and development of your body, especially during childhood, adolescence, and pregnancy. They are present in the cells and perform most of their functions at the cellular level.
Proteins exhibit different shapes and molecular weights. They may be globular in shape (for example hemoglobin) or fibrous in consistency (for example collagen).
The shape of the protein is maintained by its chemical bonds and is critical to its function. Environmental factors such as changes in temperature and pH and exposure to chemicals can cause permanent changes in the shape of the protein and lead to its loss of function. This is called denaturation.
The following are the ways your body benefits from the functions that proteins perform:
1. Enzymes that facilitate biochemical reactions
Enzymes are proteins that act as catalysts and facilitate biochemical reactions that take place in the body cells. They also help form new molecules in the cell with the help of the genetic information stored in the DNA.
Example include:
- Lactase breaks down the sugar lactose found in milk.
- Pepsin is a digestive enzyme that breaks down the protein in food.
- Salivary amylase is another example found in saliva, which helps to break down starch into sugar.
2. Body growth
Proteins are building blocks of bones, muscles, cartilage, skin, and blood. Even your hair and nails contain mostly proteins. They are essentially required for the growth and repair of all body tissues.
3. They act as messengers
Some protein hormones act as messengers that help in communicating messages between body cells, tissues, and organs.
These are the hormones that are secreted by the endocrine glands into the blood and transported to the target tissues or organs to bind to the receptors on the cell surface and take effect.
4. Provide structural support
Some proteins are fibrous in nature and provide the body tissues with strength, elasticity, and rigidity. They include keratin, collagen, and elastin.
For example:
- Keratin is a protein that provides the structure to the nails, skin, and hair.
- Collagen is the structural protein found in your bones, tendons, ligaments, and skin.
- Elastin, a flexible protein, found in the uterus, lungs, and arteries, allows for expansion and contraction.
5. Transport and storage
Proteins also help to transport important nutrients to their right destination.
For example:
- Hemoglobin, a protein, carries oxygen from your lungs to body tissues.
- Glucose transporters are a group of membrane proteins that assist the transport of glucose across the plasma membrane.
- Lipoproteins help transport cholesterol in your blood.
These protein transporters are specific and transport only that which it is meant to. Proteins also help to store iron. For example, Ferritin, a protein, helps to store iron.
6. Boosts immunity
What protects the body from unwanted invaders such as bacteria and viruses are the antibodies in the blood, which our immune system makes.
These antibodies are nothing but proteins. Without these antibodies, the harmful antigens will multiply unchecked and overcome the body with the disease they cause.