There are three types of nutrients that are essential as energy sources for the human body:
One gram of protein or carbohydrate contains 4 calories, while one gram of fat has 9 calories.
Proteins are large molecules consisting of amino acids which our bodies and the cells in our bodies need to function properly. The human body’s muscles, skin, bones and many other parts contain significant amounts of protein. In fact, protein accounts for 20% of total body weight.
What are Proteins?
The human body is made up of approximately 100 trillion cells – each one has a specific function. Each cell has thousands of different proteins, which together make the cell do its job – the proteins are tiny machines within the cell.
Amino acids and proteins – Proteins are made up of hundreds or thousands of smaller units called amino acids, which are attached to one another in long chains. There are 20 different types of amino acids that can be combined to make a protein.
Imagine there are 20 different types of bricks, and a much larger number of different types of houses which we could name according to the way we combined the bricks (their sequence). The bricks are the amino acids and the houses are the proteins.
These 20 amino acids can be arranged in millions of different ways to create millions of different proteins, each one with a specific function in the body. Amino acids are organic molecules – they are made out of carbon, hydrogen, oxygen, nitrogen and sometimes sulphur.
Functions of Proteins
- Make antibodies for our immune system.
- Make hormones, which help cells send messages and coordinate bodily activities.
- Muscle contractions – actin and myosin, two types of proteins, are involved in muscle contraction and movement.
- Make enzymes. An enzyme facilitates a biochemical reaction.
- Carry things – hemoglobin, a protein, transports oxygen through the blood.
- Store things – ferritin is a protein which stores iron in the liver.
- Protein builds, maintains, and replaces the tissues in your body.
How much protein is required?
- Infants (7 – 12 month) – 11 grams per day
- Infants (0 – 6 month) – 9.1 grams per day
- Teenage boys (14 – 18 yr) – 52 grams per day
- Teenage girls (14 – 18 yr) – up to 46 grams per day
- Adult men – approximately 56 grams per day
- Adult women – approximately 46 grams per day
- Pregnant or lactating (breastfeeding) women – about 71 grams per day
- 1 cup of milk has 8 grams of protein
- A 3-ounce piece of meat has about 21 grams of protein
- 1 cup of dry beans has about 16 grams of protein
- An 8-ounce container of yogurt has about 11 grams of protein
Health Problems that can be faced in case of Protein Deficiency
- Growth problems
- Wasting and shrinkage of muscle tissue
- Fatty liver
- Swollen belly
- Swollen legs
- Weaker immune system, leading to a higher susceptibility to infections and diseases
Sources of dietary protein
- Fish and fish eggs
- Dairy products – Milk, curd, cheese..
- Seeds and nuts
- Soy products
- Grains, vegetables and legumes also have protein
What are the Types of Proteins?
Proteins are made up of amino acids. Some of these amino acids can’t be made by our bodies, so these are known as essential amino acids. It’s essential that our diet provide these.
In the diet, protein sources are labeled according to how many of the essential amino acids they provide:
- A complete protein source is one that provides all of the essential amino acids. You may also hear these sources called high quality proteins. Animal-based foods; for example, meat, poultry, fish, milk, eggs, and cheese are considered complete protein sources.
- An incomplete protein source is one that is low in one or more of the essential amino acids. Complementary proteins are two or more incomplete protein sources that together provide adequate amounts of all the essential amino acids.
Top 10 Foods which contain Protein
- 100g Turkey Breast contains 30g protein.Chicken Breast (58g) provides 17g protein. Chicken Leg (69g) provides 18g protein. Chicken Thigh (37g) provides 9g protein.
- 100g Fish (Tuna, Salmon, Halibut) contains 26g protein.
- 100g Cheese (Non-fat Mozzarella) contains 32g protein. Low-fat Cottage Cheese (contains 5g per 28g), Low-fat Swiss Cheese (contains 8g protein per 28g), Low-fat Cheddar (6g per protein 28g), Parmesan (10g per 28 g), Romano (9g per 28 g).
- 100g Pork Loin (Chops) contains 25g protein.
- 100g Lean Beef and Veal (Low Fat) contains 36g protein.
- 100g Tofu contains 7g protein.
- 100g Beans (Mature Soy Beans) contains 17g protein.
- 100g Eggs (Especially Egg Whites) contains 13g protein.
- 100g Yogurt, Milk, and Soymilk contains 6g protein. 1 cup skim milk (245g) provides 8g protein, 1 cup soymilk (243g) provides 8g protein.
100g Nuts and Seeds (Pumpkin, Squash, and Watermelon Seeds, Peanuts, Almonds) contains 33g protein. Other nuts and seeds high in protein (grams proten per ounce (28g)): Peanuts (7g), Almonds (6g), Pistachios (6g), Sunflower Seeds (6g), Flaxseed (5g), Mixed Nuts (4g).